Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session P01: Poster Session II (2:00pm-4:00pm CDT)Poster Undergrad Friendly
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Room: Orchestra A - D - 2nd Floor |
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P01.00001: ASTROPHYSICS
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P01.00002: A new theory on the shape of the universe and the origin of the time Marcel Julmard ONGOUMAKA YANDZA According to the First Newton Law, when a physical system is not under the influence of any force, it moves linearly and its speed remains constant. This law is crucial because we know that the force is the cause of the movement. So, how can a physical body move without any force? The explanation is found in the mass of the system. According to the General Relativity, the masse is the condensation of much energy. The energy of mass is given by the equation E = mc2. Behind this mass or this energy, there is the force of mass. In our paper, we called this force, the internal force. The internal force is the force of mass in comparison to the internal energy. So, this force is the cause of movement when no force is exercising on a physical system. We know that the photon has a constant maximum speed. We can also consider a single photon as the particle with the lowest energy or the lowest mass. So, it comes an evidence that when a physical system has a low mass, its speed is high; and when its mass is great, its speed is low. This evidence leads us to this conclusion: if we consider two systems or more, when no force is exercising to them, the momentum (masse*speed) is conversed from one system to another. The value of the speed calculated by this way represents the absolute speed. The absolute speed is the speed of the physical body by referring to the light viewpoint. By this manner, we discovered that like the speed of light is always constant, its energy (or its mass) also cannot be changed. Certainly, its internal force is also invariant. We have concluded that not only celerity but all physical characteristics (speed, energy, mass, force) of the photon are invariants. In our article, A new theory on the shape of the universe and the origin of the time (doi:10.29328/journal.ijpra.1001042), we have defined the values of the physical characteristics of photon (energy, mass, force). |
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P01.00003: Improving dark matter decay sensitivities with HAWC with Inverse ComptonScattering Man Hei H Leung The particle nature of Dark Matter(DM) has been a long lasting mystery. The High Altitude |
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P01.00004: Numerical studies of inelastic dark matter cosmology Ryan Low, Rakshak Adhikari, Mikhail V Medvedev, Stephanie O'Neil, Mark Vogelsberger, Jonah Rose, Paul Torrey There are indications that the LambdaCDM paradigm may face "small-scale" problems, which would mean its incompleteness. One of a promising DM model is that with inelastic interactions in the dark sector. Here we explore the model with cosmological simulations with baryons using state-of-the-art baryonic feedback model. We discuss the effectiveness of the inelastic DM model and the interplay between DM and baryonic effects. |
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P01.00005: Neutrino Quantum Kinetics in the Early Universe Delaney Jannone, Chad Kishimoto We study the quantum kinetic evolution of neutrinos in the early universe where the hot and dense conditions result in neutrino interactions with matter and other neutrinos and anti-neutrinos. Under these conditions, neutrino-neutrino interactions can cause non-linear evolution. In this poster we explore the neutrino quantum kinetic evolution in scenarios with a net neutrino lepton-number (asymmetry between the numbers of neutrinos and anti-neutrinos). |
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P01.00006: Probing Sterile Neutrino Decays in the Early Universe with Big Bang Nucleosynthesis and Large Scale Structure Darius F Vera, kathryn anawalt, Hannah Rasmussen, Alex McNichol, George M Fuller, Chad Kishimoto
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P01.00007: Current constraints on dark matter-interacting stepped dark radiation Alexa Bartlett, Tristan L Smith, Yashvi Patel, Nils Schöneberg, Théo Simon, Guillermo Franco Abellán The Hubble and S8 tensions exist between direct and indirect measurements of the universe's expansion rate today and the clustering of matter in the universe. We examine two models constructed to alleviate both tensions. Both models inject a strongly self-interacting dark radiation (DR) fluid that also interacts strongly or weakly with some or all of the dark matter (DM). The DR energy density increases at some redshift, increasing the size of the sound horizon and thus alleviating the Hubble tension. The DM interactions suppress the growth of matter perturbations alleviating the S8 tension. The weakly interacting model is able to resolve both tensions and provide a good fit for all data. However, the inclusion of high-resolution cosmic microwave background data (ACT DR4 and SPT-3G) constrains the model and limits its ability to resolve the Hubble tension and full-shape (i.e. 'EFT of LSS') BOSS DR12 and eBOSS galaxy clustering limits its ability to resolve the S8 tension. The strongly interacting model incorporates dynamics that extend to later times than the weakly interacting model, leading to tight constraints using Planck CMB data alone. We investigate how these data sets respond to these models in order to understand the requirements for mechanisms to address both tensions. |
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P01.00008: Advancing cosmic density field reconstruction with machine learning and statistical methods Xinyi Chen, Nikhil Padmanabhan, Fangzhou Zhu, Sasha Safonova The baryon acoustic oscillation (BAO) technique is one of the most powerful probes of dark energy and has been playing an important role in large galaxy surveys in the last decade. The effects of late-time nonlinear structure formation, however, wash out the acoustic peak of the correlation function, reducing the precision of BAO distance scale measurements. Reconstructing the nonlinear density field reverses these adverse effects and increases the precision of the measurements. A standard reconstruction method has been used in observations for a decade and has reduced the uncertainty on the BAO scale by about a factor of two. However, ongoing and next-generation surveys, such as the Dark Energy Spectroscopic Instrument, Nancy Grace Roman Space Telescope, and Euclid, will offer unprecedented precision measurements of cosmological parameters and thus will greatly benefit from improvements in reconstruction to more fully realize their potential. We present new methods of reconstruction that use machine learning and statistical tools. In particular, we show our investigation of reconstruction for fields of low number densities, at the level achievable by current surveys. |
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P01.00009: Olimpo: A Balloon-Borne Instrument to Probe Dynamic Structure Formation and the WHIM Scott Cray, Camille Avestruz, Ritoban Basu Thakur, Elia Battistelli, Paolo de Bernadis, Esra Bulbul, Federico Cacciotti, Fabio Columbro, Alessandro Coppolecchia, Giancarlo De Gasperis, Shaul Hanany, Luca Lamagna, Silvia Masi, Alessandro Paiella, Marco De Petris, Giorgio Pettinari, Francesco Piacentini, Larry Rudnick, Jack Sayers, Irina Zhuravleva We describe OLIMPO, a proposed balloon-borne instrument to map 10 galaxy clusters and 4 emission bridges using the thermal and kinematic Sunyaev-Zel'dovich effects. OLIMPO will have a 2.6 m telescope, four frequency bands between 150 and 460 GHz, and a kilopixel array of kinetic inductance detectors. OLIMPO's measurements will for the first time directly probe internal intracluster medium gas motions from the cluster's center to its outskirts at a radius of 1.5 Mpc, giving unprecedented views of the dynamics of cluster formation. In addition, OLIMPO's mapping of emission bridges will transform the search for the missing baryons thought to reside in the filaments connecting clusters in the form of a warm hot intergalactic medium. The OLIMPO data will be complemented by state-of-the-art X-ray data from the eROSITA and XRISM satellites, radio data from ASKAP and MeerKAT, and from cosmological simulations. The science goals require X-ray data with high sensitivity to the diffuse gas in cluster outskirts and filaments, which are almost exclusively available only for low z, degree-scale objects best observed from above the atmosphere. With a single flight in late 2026, OLIMPO is expected to provide maps at least 17 times more sensitive to low z clusters than the 2030's survey by CMB-S4. |
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P01.00010: Systematic study of projection biases in weak lensing analysis Prudhvi Raj Varma Chintalapati, Gaston R Gutierrez, Michael H Wang We present a systematic study of projection biases in the weak lensing analysis of the first year of data from the Dark Energy Survey (DES) experiment. In the analysis, we used a ΛCDM cosmology model and the three two-point correlation functions: (i) the cosmic shear correlation function, (ii) the galaxy angular correlation function (galaxy clustering), and (iii) the galaxy-shear cross-correlation function (galaxy-galaxy lensing). We show that these biases are a consequence of projecting or marginalizing, over parameters like h, Ωb, ns, and Ωνh2 that have wide likelihoods with respect to their priors (poorly constrained) and correlated with the parameters of interest like Ωm, σ8, and S8. Covering the relevant parameter space, we show that the projection biases are a function of where the true values of the poorly constrained parameters lie with respect to the parameter priors. We also show that the one-dimensional credible intervals are consistently inflated and discuss how careful study of these biases could transform the WL analysis credible intervals into confidence intervals with an equivalent gain of up to three times the data available to the experiment. |
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P01.00011: Topological data analysis reveals differences between galaxies and dark matter halos Aaron Ouellette, Gilbert Holder We use topological summaries based on Betti curves to characterize the large-scale spatial distribution of dark matter halos and galaxies. Using the IllustrisTNG and CAMELS-SAM simulations, we show that the topology of the galaxy distribution is significantly different from the topology of the dark matter halo distribution. Further, there are significant differences between the distributions of star-forming and quiescent galaxies. These topological differences are consistent across all simulations considered, while at the same time there are noticeable differences when comparing between different models. Finally, using the CAMELS-SAM simulations, we show that the topology of the quiescent galaxies, in particular, depends strongly on the amount of supernova feedback. These results suggest that topological summary statistics could be used to help better understand the processes of galaxy formation and evolution. |
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P01.00012: Modeling Datasets with Field-Level and Halo-Centric Inference via Machine Learning Naomi Gluck Neural networks can be utilized for improving the precision and accuracy of current and future multiwavelength cosmological and deep astronomical observations in two distinct methods. First, with cosmological field-level parameter inference from continuous datamaps. Now, novel astrophysical and observational parameters undergo halo-centric parameter inference to predict Circum-Galactic Medium (CGM) properties with only discrete points. In combining these, we aim to identify areas of interest for cosmological surveys and astronomical observations from featured neural network outputs. The CAMELS Multifield Dataset provides data-driven methods for constraining both cosmological and astrophysical (baryonic feedback) parameters. We can use parallel methods for new inferences on CGM properties, for example, using simulated IllustrisTNG data of HI and X-ray to probe cool cosmic neutral hydrogen gas and hot cosmic gas, respectively. With fewer data per set, multiple CGM parameters must be trained together for robust constraints – the network is flexible enough to handle this. This method will vastly optimize the decisions for observational surveys around galaxies, and provide a pipeline for future analyses using other simulations to create a more accurate picture of the Universe. |
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P01.00013: Sky localization of Un-modeled Gravitational Wave Sources with Machine Learning Ethan J Marx, Deep Chatterjee, Alec Gunny, William Benoit, Rafia Omer, Michael W Coughlin, Erik Katsavounidis, Muhammed Saleem, Eric Moreno, Dylan S Rankin, Philip C Harris, Ryan J Raikman During the first 3 observing runs the LIGO-Virgo-Kagra collaboration (LVK) has made over 90 detections of gravitational waves, all from compact binary coalescences (CBCs). Beyond these is another category of possible sources, short-duration (around ~1s), un-modeled transients. These sources do not have well-modeled templates of the gravitational wave emission. Plausible astrophysical progenitors include core-collapse supernovae (CCSNe), pulsar-glitches, with the additional possibility of detecting an unexpected source. Accurate and rapid parameter estimation of these un-modeled gravitational wave transients is vital for informing electromagnetic follow up. Many Bayesian methods can take hours to days to converge to accurate posterior estimates. As an alternative, machine learning approaches have been shown to offer comparable accuracies with significantly faster inference times. In this work, we present a machine learning framework that utilizes normalizing flows to perform real-time parameter estimation for un-modeled gravitational wave sources. To train our model, we use ad-hoc Sine-Gaussian waveforms that make minimal assumptions about the source. We demonstrate the ability of our model to accurately recover sky localization parameters from sources modeled with Sine-Gaussians embedded in real data from the LVK third observing run. |
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P01.00014: Recovering the Mass-Tide Relationship for Neutron Star Mergers With Future Observations Emily Wuchner, Jocelyn S Read, Philippe Landry We report the usage of the Bilby Bayesian inference library (Ashton et al. (2019)) as a tool to demonstrate the expected future improvement in the recovery of tidal parameters across a wide range of masses when Advanced LIGO reaches design sensitivity, or when Cosmic Explorer and Einstein Telescope are implemented. We have run an artificial population of parameter estimation runs using Bilby software. We focused on the implications for recovering tidal parameters across different source masses, which can be compared with the predictions of a given equation of state for neutron-star matter. For realistic recovery errors, it is important to account for the spin of the star. Allowing unlimited spins leads to larger uncertainties in recovered tides. We also demonstrate that it is important to account for differences between source-frame and detector-frame masses due to redshift, as using detector-frame masses gives a measurable offset from the assumed relationship between mass and tidal parameters. |
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P01.00015: New analyses searches in the Neutrino Electromagnetic Channel with AMON Hugo Ayala The Neutrino-Electromagnetic channel of AMON has been running for the past 3 years. This channel receives subthreshold data from multiple observatories in order to look for coincidences. Combining more than two datasets at the same time is challenging because of the infinite range of possible signals. By using outlier detection methods, we can circumvent this issue by identifying any signal divergent from the background (scrambled data). We propose to use these methods to make a model independent combination of the subthreshold data of neutrino and gamma ray experiments. |
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P01.00016: 2-D Visualization of Time Dependence in Cosmic Ray Anisotropy using IceCube Emily R Schmidt, Christina Cochling, Benjamin Pettee, Frank T McNally Over the last 11 years, the IceCube Neutrino Observatory has recorded over 694 billion cosmic-ray events. We observe an anisotropy in the arrival direction distribution of these cosmic rays that, at least qualitatively, appears to be constant over time. However, detailed quantitative comparison is required to properly search for time-variation in the signal. With the immense statistics across a substantial length of time, there is a need for visual graphics that allow straightforward interpretation of the data. In this study, we consider both 1- and 2-D visualizations of relative intensity over time. One-dimensional projections along right ascension are well-established within IceCube, but potentially lose valuable information. By instead comparing each year's skymap to a baseline, we can calculate the p-value for each pixel and display them two-dimensionally. This process pinpoints any excesses or deficits in relative intensity across time to specific parts of the sky. We present preliminary results on this study, including potential indicators of time-variation within the signal. |
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P01.00017: PSRmatch: Cross Matching Binary Pulsars with Gaia Sources to Improve Pulsar Distance Estimates Annika Deutsch, H. Thankful Cromartie, Jim Cordes, Shami Chatterjee Pulsars are highly magnetized, spinning neutron stars that emit electromagnetic radiation out of their off-axis magnetic poles. Distance estimates to pulsars can be obtained through several methods, including radio interferometry, dispersion measure, and timing parallaxes, to name a few. But distance estimates to pulsars are just that—estimates—and for applications such as pulsar timing for nanohertz gravitational wave detection, it is important to constrain the distances to pulsars as best we can. One method of obtaining independent distance estimates to pulsars is via cross matching data from the European Space Agency’s Gaia mission with pulsar data in search of companions to binary pulsars. |
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P01.00018: 21 New Pulsar Timing Solutions from the GBNCC Pulsar Survey William C Fiore, Maura A McLaughlin We present timing solutions for 21 pulsars discovered in 350 MHz surveys using the 100-m Green Bank Telescope (GBT). These pulsars were discovered in the Green Bank North Celestial Cap (GBNCC) pulsar survey, a 350 MHz all-GBT-sky pulsar survey; except for one discovery from the GBT 350 MHz Drift-scan pulsar survey. These timing solutions are the result of a dedicated ~year-long GBT timing campaign at 820 MHz. Where applicable, we also incorporate observations from discovery, confirmation, and initial followup with the GBT at 350 MHz, additional GBT followup from 350−2000 MHz, and observations using the Arecibo radio telescope, Long Wavelength Array (LWA), and Low Frequency Array (LOFAR). PSRs J0032+6946 and J0214+5222 are mildly recycled pulsars in wide, >1-year-period binaries. PSRs J0141+6303, J1327+3423, and J1434+7257 are disrupted recycled pulsars: their spin periods ~40 ms and magnetic fields <1010 G are evidence of past accretion, but each lacks a binary companion. PSR J0636+5128 is a non-eclipsing “black widow” MSP in a 1.6-hr orbit, and is observed by pulsar timing arrays searching for low-frequency gravitational waves. PSR J1239+3239 is an MSP in a 4-day orbit with a binary companion. The “redback” PSR J1816+4510 is an eclipsing binary MSP, for which we measure the derivative of projected semimajor axis, d (a × sin(i) / c) / dt = -1.0(2) × 10-13. The remaining pulsars are isolated, canonical pulsars, including the rotating radio transient (RRAT) PSR J0957−0619 and nulling pulsars PSRs J1530−2114, J2145+2158, and J2210+5712. |
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P01.00019: On motion of an charge in a magnetar magnetosphere Mikhail V Medvedev Neutron stars and magnetars possess extremely strong magnetic fields. Radiative cooling of plasma particles in their magnetospheres can be short compared to the plasma dynamical time. Such magnetospheres are observed to produce strong flares, which indicates production of a relativistic pair plasma. How does the particle distribution change as these particles propagate in the magnetospheric 'magnetic trap'? Here we discuss the motion of a relativistic charge in a straight magnetic trap subject to radiative energy loss. |
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P01.00020: Analysis Progress: SuperTIGER Abundances of Galactic Cosmic Rays for the Atomic Number (Z) Interval 40 to 56 Nathan E Walsh, Brian F Rauch, Wolfgang Zober, Yosui Akaike, Walter Binns, Theresa J Brandt, James H Buckley, Nicholas W Cannady, Priyarshini Ghosh, Thomas Hams, Martin H Israel, John F Krizmanic, Allan W Labrador, Richard A Mewaldt, John W W Mitchell, Ryan P Murphy, Georgia A de Nolfo, Scott Nutter, Kenichi Sakai, Makoto Sasaki, Edward C Stone, John E Ward, Teresa Tatoli, Mark E Wiedenbeck SuperTIGER (Super Trans-Iron Galactic Element Recorder) is a long-duration-balloon instrument that completed its first Antarctic flight during the 2012-2013 austral summer, spending 55 days at an average float altitude of 125,000 feet. SuperTIGER measured the relative abundances of Galactic cosmic-ray (GCR) nuclei with high statistical precision and well resolved individual element peaks from 10Ne to 40Zr. SuperTIGER also made exploratory measurements of the relative abundances up to 56Ba. GCR measurements up to 40Zr support a source acceleration model where supernovae in OB associations preferentially accelerate refractory elements that are more readily embedded in interstellar dust grains than volatiles. In addition, injection into the GCR for both refractory and volatile elements appears to follow a charge dependence consistent with their grain sputtering cross sections. Although statistics are low for elements heavier than 40Zr, our preliminary measurements of the 40Zr to 56Ba range suggest the existence of an alternative GCR source or acceleration model for these rare elements. We report progress in refining this interesting result. |
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P01.00021: Cosmic-Ray Energy Reconstruction in IceCube Using a Convolutional Neural Network with Low-Level Inputs Ethan Dorr, Frank T McNally, Kennedy Mays, Caden Hamrick, Marlon Oliver, Kriti Mittal The purpose of our research is to build a convolutional neural network capable of energy reconstructions using data detected at the IceCube Observatory for use with high-statistics, minimally-cut cosmic-ray anisotropy studies. Our goal is to use simulation from the IceTop surface array to build a lightweight model that can successfully reconstruct contained and uncontained events over a large zenith range. By using only low-level charge and time information as inputs, we hope to minimize the amount of systematic uncertainty in our model while maintaining the accuracy of models whose input includes higher-level parameters. Current research primarily focuses on improving our model by normalizing input and clipping time data, as well as introducing rotational invariance by rotating the simulated events. Our current model is capable of estimating 68% of unfiltered simulations within 15% of their true energies. |
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P01.00022: Investigating the Quiescent State of NGC 1275 with VERITAS and Multi-Wavelength Observations Anjana Kaushik Talluri The VERITAS observatory is a ground-based air Cherenkov telescope array that detects very-high-energy gamma-ray emission (VHE; > 100 GeV) from a range of astrophysical sources including more than 80 Active Galactic Nuclei (AGN). The majority of these AGN are blazars where relativistic jets aligned within a few degrees to our line of sight cause the observed radiation to be highly Doppler boosted. Radio galaxies are AGN with jets viewed at systematically larger angles to the line of sight, making these objects more challenging to detect in VHE gamma rays. Even so, a few radio galaxies are detected in the VHE including NGC 1275 (3C 84), the central galaxy in the Perseus cluster (z∼0.0176), in which the origin of TeV emission is not still entirely understood. NGC 1275 has a long history of observations across all wavebands, and a very complex morphology that has evolved with time. A study of the January 2017 flare with VERITAS observations found that a multi-component model was required to fit the multi-wavelength spectral energy distribution (SED). In the study presented here, we investigate the quiescent (non-flaring) state of NGC 1275 constructing an SED with contemporaneous observations from Swift-XRT, Swift-UVOT, Fermi-LAT, ALMA, and ATLAS telescopes over the period 2012-2017. |
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P01.00023: New Techniques in Sensor Waveform Processing for the IceCube Neutrino Observatory Joshua H Peterson, Jim Braun, Kael D Hanson, John Kelley Future extentions of the IceCube Neutrino Observatory will include many strings of digital optical modules (DOMs), each with multiple photomultiplier tubes (PMTs). In order to reduce the bandwidth requirements of the deep-ice cable, part of the processing of the PMT voltage waveforms will occur in the DOMs instead of sending all raw voltage waveforms to the surface. We demonstrate that implementing the first step of the Lawson-Hanson non-negative least squares algorithm on a microcontroller unit in the DOMs can process dark noise hits by unfolding the waveform using the PMT single photoelectron response. This single photoelectron (SPE) processing algorithm can be accelerated substantially by incorporating additional SPE time information. In addition, we present a new voltage waveform processing algorithm utilizing neural networks that was developed to potentially accelerate voltage waveform processing. |
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P01.00024: Analytically Evaluating the Stability of Multi-Planet Systems with Binary Companions Kristina Gatto There is reason to believe, based on prior research, that in a number exoplanet systems, there could be currently unknown binary companion stars orbiting alongside the planets. I was able to investigate this idea through creating simulations of exoplanet systems using a computational approach. I created a python pipeline that ran simulations of hypothetical exoplanet systems to determine where a hypothetical binary companion star could physically exist within the system and produced detailed graphs of the results. These graphs showed at what distance and eccentricity these binary companions could theoretically lie. I was later able to utilize this pipeline to run simulations of real life exoplanet systems with suspected binary companions to determine where they may exist and am still in the process of sorting through these systems. Using the simulations I created, I have been able to determine that a number of real life exoplanet systems produced results that proved a binary companion star could possibly exist within the system. This provides futher confirmation and evidence for future research on these hypothetical binaries. I look forward to turning this pipeline into a python package that can be used more widely. |
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P01.00025: Probing the Physics of the Circumgalactic Medium using Fast Radio Bursts: Insights from CAMELS Isabel Medlock, Daisuke Nagai The physics of the circumgalactic medium (CGM) is complex and not well understood. It is essential that we understand the processes and properties of baryons in the CGM as within are encoded formation history, feedback mechanisms of galaxy evolution, and a portion of the “missing” baryons. In the era of multi-wavelength astronomical surveys, one promising probe of the CGM are fast radio bursts (FRBs), millisecond-long luminous extragalactic pulses. The dispersion measure (DM) of FRBs is useful for quantifying and locating baryons in the CGM as it is solely a function of the electron density distribution. We analyze the CAMELS simulations, comprising over 6000 state-of-the-art cosmological simulations, and spanning a wide range of astrophysical and cosmological parameters. We explore how the implementation of CGM physics impacts the DM of FRBs. We investigate the distribution of DM resulting from varying cosmological (ΩM, σ8) and astrophysical parameters (stellar and AGN feedback), finding that ΩM and the star formation rate result in significant differences in the distribution of DM. We explore the evolution of DM with redshift, comparing to previous models. We measure the excess DM associated with FRBs that interact with the CGM. Finally, we calculate the F parameter, an essential parameter that quantifies the effect of feedback, for each simulation run. We include a correction factor to F to account for the lack of representative cosmic variance due to the small box size. |
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P01.00026: GRAVITATION
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P01.00027: Extension of General Relativity Frank S Hafner A full scale fifth spacetime dimension provides an extension of general relativity, thus the Universe expands along two degrees of freedom, parallel and normal to light. Our eyes see parallel expansion. Normal expansion is the unwinding of spacetime as Universe mass density decreases. Near Universe inception, there was near infinite mass density causing near infinite spacetime curvature. As density decreased, so did spacetime curvature. A tetherball shows this – the ball moving around the pole is the curved path of light. The ball moving away from the pole one pole circumference per revolution represents normal expansion. The eye perceives two dimensions, but motion on the human scale provides the illusion of a three-dimensional view. The universe does not have human scale motion. Slower observations are needed for visualization in the mind of the fifth spacetime dimension - primarily the illusion of the effects of dark energy. There is a semipermeable interface between Minkowski space and the fifth spacetime dimension. Quasi-tunneling of wave/particles and gravity into the fifth dimension creates potential explanations for little understood phenomena - dark matter, ultra-high energy gamma rays, and maybe a means for superluminal travel… The slightest momentum in the fifth spacetime dimension may have prevented the early universe from sliding back into the Big Crunch. Each dimension is normal to the previous through the fifth spacetime dimension - all dimensions are the same in this respect. |
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P01.00028: A Comparison of G Inside and Outside of Cosmic Voids Christopher W Stubbs, Eske M Pedersen Various models of modified gravity invoke ``screening'' mechanisms that are sensitive to the value of the local gravitational potential. This could have observable consequences in the internal kinematics of galaxies. Motivated by this prospect, we have conducted a comparison of the observable properties of luminous red galaxies (LRGs) inside and outside of voids in the cosmic large scale structure. We used archival measurements of line widths, luminosities, redshifts, colors, and positions of galaxies in conjunction with recent void catalogs to construct comparison LRG samples inside and outside of voids. We use fits to the well-established fundamental plane of elliptical galaxies to constrain any differences between the aggregate properties of the two samples. We will present preliminary constraints on the fractional difference in the value of the gravitational constant G that governs the internal kinematics of elliptical galaxies within and outside of cosmological voids. This places observational constraints on screened gravity theories. |
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P01.00029: Numerical study of generic, expanding T2-Symmetric vacuum spacetimes Beverly K Berger, James A Isenberg, Adam Layne Generic expanding T2-Symmetric vacuum spacetimes contain two gravitational-wave polarizations propagating in a background spacetime with the metric depending on only one spatial variable and time as well as extra off-diagonal metric components described as non-zero twist and non-zero constants of the motion A and B defined as spatial integrals of nonlinear combinations of the metric variables and their first derivatives. The objective is to identify an asymptotic description of the expansion. Rigorous mathematical results exist for subclasses of the generic case characterized by B = 0 [1, 2]. So far, no rigorous results exist for the B ≠ 0 class. A numerical study is presented to show (1) where the mathematical methods used for B = 0 in [2] fail for B ≠ 0, (2) how the power laws describing the expansion of the spatially averaged variables in expanding T2-Symmetric spacetimes may be found numerically (for all values of B), (3) how spatially averaged variables may be constructed in these spacetimes to demonstrate (different) sink-like attractors for both the B = 0 and B ≠ 0 classes, and (4) that the B ≠ 0 class exhibits an interchange of “energy” between the two gravitational-wave polarizations (if B ≠ 0 but not if B = 0). |
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P01.00030: Anisotropic Searches for Stochastic Gravitational Wave Backgrounds and Foregrounds with the Bayesian LISA Pipeline (BLIP) Alexander W Criswell, Steven M Rieck, Malachy Bloom, Jessica Lawrence, Sharan Banagiri, Joseph D Romano, Vuk Mandic LISA data is expected to feature at least one significant anisotropic stochastic gravitational wave (GW) signal: a galactic foreground comprised of the GW contribution from millions of unresolved double white dwarf (DWD) binaries throughout our galaxy. We use the Bayesian LISA Pipeline (BLIP) to simulate a realistic, population-derived stochastic signal from unresolved DWDs in the Milky Way, and apply BLIP’s all-sky spherical harmonic analysis to perform an anisotropic search for the resulting foreground. We present the results of this search alongside new insight into the angular resolution of the spherical harmonic search, and discuss directions of further development in the area of anisotropic stochastic searches and characterization of the galactic foreground with LISA. |
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P01.00031: Cross-Correlation Analysis of Anisotropic Stochastic Gravitational Wave Background with Electromagnetic Tracers and Methods in Dealing with the Inverse Fisher Matrix Alex E Granados, Vuk Mandic To date, only upper limits for the anisotropic stochastic gravitational wave background (SGWB) have been reported. The cross-correlation of the anisotropic SGWB with different electromagnetic tracers (such as galaxy counts or weak lensing) has the potential to aid in detecting the anisotropic SGWB sooner than directly detecting it. However, an issue in performing the cross-correlation analysis is removing the detector response from the observed gravitational wave data, which implies inversion of an ill-defined Fisher matrix. Past studies have approached the problem by regularizing the Fisher matrix. This approach has been proven successful in studies with relatively low angular resolution. I am working on an alternative method that avoids inversion of the Fisher matrix, hence avoiding placing limitations on the angular resolution of the analysis. |
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P01.00032: Verifying LIGO–Virgo GWTC-2 Nested Sampling with Order Statistics Talya Klinger The LIGO-Virgo Collaboration utilises nested sampling to infer the source properties of compact binaries, computing Bayesian evidences and posterior distributions. With poor sampling from the constrained prior, nested sampling algorithms may misbehave and fail to sample the posterior distribution faithfully. Fowlie et al. (2020) outlines a method of identifying pathologies such as plateaus in the parameter space, using likelihood insertion order statistics. We apply this method to nested sampling analyses of all events in the first and second gravitational wave transient catalogs. With a few exceptions that have negligible effect on the final posteriors, the data is consistent with uniform insertion order statistics and unbiased prior sampling. There is, however, weak evidence against uniformity at the catalog-level meta-test. |
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P01.00033: Identifying strongly lensed gravitational waves using phase consistency Jose Ezquiaga, Wayne Hu, Rico Ka Lok Lo Strongly lensed gravitational waves (GWs) are detected as repeated chirps of the original binary merger. At each of the detectors, the phase of the lensed GWs will be consistent modulo a fixed constant phase shift (multiples of π/2) which depends on the part of the lensing potential crossed by each copy. We develop a fast and reliable method to identify strongly lensed GWs exploiting that phases at each detector are the best measured GW parameter, with errors only of a fraction of a radian (ΔΦ ~ 1/SNR). Our basic statistic determining the consistency of two GW events with the lensing hypothesis is the distance between the posterior distribution of phases at each of the detectors. The posterior distribution of phases at detectors can be well approximated by Gaussian distributions, and therefore the distance can be trivially computed. This method avoids the shortcoming of looking for overlaps in highly non-Gaussian sky-maps, as well as the issue with the prior volume of the masses and other intrinsic parameters of the binary not being well defined. |
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P01.00034: Weighing the Likelihoods of Equations of State with Gravitational Wave Observations Sunny Ng, Philippe Landry, Isaac Legred, Reed Essick, Jocelyn S Read In the age of gravitational waves, multi-messenger Neutron Star observations can provide insights to the extreme matter within them. With this aim, we have streamlined a Bayesian Hierarchical Inference scheme previously used for nonparametric equation of state (EOS) inference. The hierarchical inference takes in EOS realizations and constrains their posterior probability by weighting them according to the likelihood of gravitational-wave observations of compact binary coalescences, to a 90% credible interval. We implement an analysis using a set of EOS realizations generated by a Gaussian process, exploring the space of all causal and thermodynamically stable pressure-density functions, including those with first-order phase transitions. Using the inference code, we probe the speed of sound within the core and compare with the conformal limit. |
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P01.00035: Exploring astrophysical priors for gravitational-wave inference of neutron star source properties Marc B Penuliar, Jocelyn S Read, Philippe Landry, Carl-Johan O Haster The inferred properties of gravitational-wave source systems are sensitive to prior assumptions about the source populations. We explore the implications for GW190425 and GW170817 under the assumption of various 'realistic' population properties, including a neutron-star mass and spin distributions motivated by observations of pulsars in our galaxy and a common equation of state linking the tidal parameters. In some cases, reweighting of public samples can be used to determine the effect of changing priors, but as priors become more constraining the application of reweighting is limited by the samples available. To explore the impact of inferring a common equation of state, we also implement and test the "binary love" universal relations previously used to infer properties of GW170817 in the Bayesian inference library bilby. This will allow direct inference of a source's properties using bilby under the assumption that both components share the same equation of state. |
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P01.00036: Goal-Oriented Neural Network Surrogates for Gravitational Wave Models Bassel Saleh, Omar Ghattas, Tom O'Leary-Roseberry, Brendan Keith Fast gravitational wave models are needed in order to solve the Bayesian inverse problem at the heart of LIGO data analysis. To get around computationally expensive solvers for Einstein's equations in numerical relativity, a broad array of surrogate models has been developed to make such analyses tractable. These models utilize physical approximations as well as data-driven approaches to create synthetic waveforms that can be compared to LIGO data. In this work, we build on recent developments in using neural networks to learn the morphology of a signal generated by more expensive gravitational wave models. We use proper orthogonal decomposition to find dimensionally reduced representations of gravitational wave signals, and we then train neural networks to learn coefficients in this reduced basis from binary black hole parameters such as mass and spin. Furthermore, we introduce known noise characteristics of the LIGO and Virgo detectors via the power spectral density (PSD), in order to guide the reduced basis construction to reflect the sensitive frequencies of the detections. This goal-oriented approach allows our models to perform better in the inverse problem, producing posteriors that match the high-fidelity reference better than similar models that don't incorporate PSD information, according to computed Jensen-Shannon distances. We demonstrate this improvement in simplified settings using training data generated by the PhenomX family of gravitational wave models. |
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P01.00037: Accelerating Tests of General Relativity with Gravitational-Wave Signals using Hybrid Sampling Noah E Wolfe, Colm Talbot, Jacob Golomb The Advanced LIGO/Virgo interferometers have observed ~100 gravitational-wave transients |
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P01.00038: On the Detectability of a Stochastic Gravitational Wave Background from the White Dwarf Binaries in the LMC with LISA Steven Rieck, Alexander W Criswell, Vuk Mandic, Sharan Banagiri, Joseph D Romano, Jessica Lawrence In the 2030s, the Laser Interferometer Space Antenna (LISA) will provide astronomers with the first tool to study gravitational waves (GWs) in the millihertz frequency range. In addition to individual binary sources, LISA will detect a stochastic GW foreground signal from the incoherent superposition of many double white dwarf (DWD) binary systems in the Milky Way. The detectability of similar backgrounds from nearby dwarf galaxies was unknown until this work. We evaluate the detectability of a stochastic GW background signal from the DWDs in the Large Magellanic Cloud (LMC). The LMC is an ideal first candidate due to its large size and close proximity relative to other dwarf galaxies. We use the Bayesian LISA Pipeline (BLIP) to simulate the stochastic GW signal and perform recovery and Bayesian parameter estimation in the spherical harmonic basis via nested sampling. We simulate the LMC signals from a DWD population using realistic population synthesis catalogs. While prospects for signal characterization must be studied further, initial results indicate that the LMC stochastic background will be detectable by LISA. |
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P01.00039: Bayesian parameter estimation for targeted anisotropic gravitational-wave background Leo Tsukada, Erik Floden, Deepali Agarwal, Santiago Jaraba Extended sources of the stochastic gravitational backgrounds have been conventionally searched on the spherical harmonics bases. The analysis during the previous observing runs by the ground-based gravitational wave detectors, such as LIGO and Virgo, have yielded the constraints on the angular power spectrum $C_ell$, yet it lacks the capability of estimating other parameters such as a spectral index. |
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P01.00040: Identifying Glitches in LIGO Gravitational Wave Data with Machine Learning Algorithms Kalista Wayt, Madeline Wade, Leslie E Wade The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a ground-based interferometer used to detect gravitational waves from some of the most spectacular astrophysical events in the Universe. Gravitational waves from these objects manifest as nearly imperceptible changes in distance (strain), requiring an unparalleled level of sensitivity in order to distinguish such signals from a noisy background. Our world is noisy, and the noises we encounter are everyday occurrences that have little to no effect on our lives, but with LIGO, this noise does matter. LIGO's main strain channel is contaminated with loud and transient noise artifacts, called "glitches," which has required LIGO to use instruments dedicated to tracking possible causes of noise. This information is recorded in auxiliary channels. My overall goal is to develop a machine learning algorithm (MLA) that uses information from the auxiliary channels to perform real-time predictions about the presence of glitches in the strain data. Previous attempts at constructing an MLA had large variability in effectiveness daily. We hypothesized that this was because of the time-changing nature of the detector. Therefore, the activity in the auxiliary channels and potential glitches they might register also changes over time. Since we were using consecutive time training sets, we theorized that the MLA would only learn the specific auxiliary channel indicators present during that period. However, these same channels may not be active later in the observing run, thus causing the MLA to lose any ability to identify glitches in the strain through auxiliary channel information. Here, I will show the results of our newest attempt to improve our ability to predict glitches over an observing run using a hierarchical method for the auxiliary subsystems; or, in other words, our ability to correctly predict a glitch in the strain when we create custom models for each auxiliary subsystem of LIGO and combine the predictions from these MLAs to get one overall result. I will also present our proposition to improve the MLA by creating the hierarchical method using glitch types as the subcategories instead. |
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P01.00041: Using Pulsar Classifying Machine Learning Algorithms To Increase Pulsar Timing Array Sensitivity Olivia S Wilk, Leslie E Wade A pulsar is a neutron star that emits electromagnetic radiation along its magnetic pole and spins extremely fast. Millisecond pulsars, in particular, rotate hundreds or thousands of times per second and to atomic clock-level precision. Knowing the precision of a millisecond pulsar allows scientists to observe gravitational waves using the discrepancies in pulse timing as measured on Earth. Discovering more pulsars will enable us to increase the sensitivity of these extensive collections of pulsar data, also known as Pulsar Timing Arrays. Radio telescopes detect new pulsar candidates, but the majority of candidate data consists of non-pulsar radio sources, such as Radio Frequency Interference (RFI) and noise. Humans have manually verified pulsar candidates, but using machine learning algorithms (MLA) to sort the candidates can save incredible amounts of time and increase efficiency. This project focuses on an existing pulsar classifying MLA, PulsAr Classifier - Machine-learning Algorithm with Neural Networks (PACMANN). One difficulty encountered during the use of PACMANN is that we have far more data for non-pulsar candidates than pulsar candidates, which means that the MLA is learning from either an unbalanced data set or an incredibly small one, which could decrease the MLA’s overall performance. Proposed solutions include injecting simulated pulsar signals into the dataset or balancing the existing data using class weights. For this project, we focused on implementing both solutions and aimed to use PACMANN to identify new pulsar candidates. |
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P01.00042: Constraining cosmological anisotropy using standard sirens from the next generation of gravitational wave detectors Bryce Cousins Measurements of the accelerating expansion of the Universe have resulted in a significant tension in values of the Hubble-Lemaître parameter H, suggesting an issue with the standard cosmological model. One method to investigate this tension is to allow for cosmological anisotropies, instead of assuming isotropy as in the standard cosmological model. Anisotropies have been suggested by studies of a dipole in H via standard candle supernovae, anisotropic quasar populations, unusual features in the cosmic microwave background, and a dipole in the fine-structure constant. The current work assesses the potential of the next-generation of ground-based gravitational wave detectors to study anisotropic cosmology via the luminosity distances of standard sirens. Projected constraints on a dipole anisotropy are assessed using two sets of 100,000 simulated binary neutron star mergers for six networks of current and next generation gravitational wave detectors. A non-Friedmann-Lemaître–Robertson–Walker expansion is used for the luminosity distance model, allowing the simulations to constrain non-standard cosmologies. The potential constraints of these simulated datasets will be presented. |
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P01.00043: Extending the reach of pulsar timing arrays to micro-hertz GW frequencies Nihan Pol, Stephen R Taylor, Diego Blas, Alex Jenkins, Aditya Parthasarthy, Michael Kramer We present a framework that leverages the effect of binary resonance to search for micro-hertz GWs using pulsar timing arrays. We modify the pulsar timing array likelihood to capture the binary resonance effect and calculate the sensitivity of this micro-hertz GW detector using the binary pulsars in the NANOGrav 12.5 year dataset. |
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P01.00044: Measuring Supermassive Black Hole Properties via Gravitational Radiation from Eccentrically Orbiting Stellar Mass Black Hole Binaries Andrew S Laeuger, Brian C Seymour, Yanbei Chen, Hang Yu There may exist stellar-mass binary black holes (BBH) which merge while orbiting nearby a supermassive black hole (SMBH). In such a triple system, the SMBH will modulate the gravitational waveform of the BBH through orbital Doppler shift and de Sitter precession of the angular momentum. Future space-based GW observatories focused on the milli– and decihertz band will be uniquely poised to observe these waveform modulations, as the GW frequency from stellar-mass BBHs varies slowly in this band while modulation effects accumulate. In this work, we apply the Fisher information matrix formalism to estimate how well space-borne detectors can measure properties of BBH+SMBH hierarchical triples using the GW from orbiting BBH. We extend previous work by considering the more realistic case of eccentric orbit around the SMBH, and notably include the effects of orbital pericenter precession. We find that for detector concepts such as LISA, B-DECIGO, and TianGO, we can extract the SMBH mass and semimajor axis of the orbit with a fractional uncertainty below the 0.1% level over a wide range of triple system parameters. Furthermore, we find that uncertainties can improve significantly when the BBH takes an eccentric orbit around the SMBH. We also find that while LISA could measure these systems, the decihertz detector concepts B-DECIGO and TianGO would enable better sensitivity to the triple's parameters. |
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P01.00045: Tests of General Relativity with Gravitational-Wave Observations using a Flexible--Theory-Independent Method Ajit K Mehta We perform tests of General Relativity (GR) with gravitational waves (GWs) from the inspiral stage of compact binaries using a theory-independent framework, which adds generic phase corrections to each multipole of a GR waveform model in frequency domain. This method has been demonstrated on LIGO-Virgo observations to provide stringent constraints on post-Newtonian predictions of the inspiral and to assess systematic biases that may arise in such parameterized tests. Here, we detail the anatomy of our framework for aligned-spin waveform models. We explore the effects of higher modes in the underlying signal on tests of GR through analyses of two unequal-mass, simulated binary signals similar to GW190412 and GW190814. We find that to optimize the GR test of high-mass binaries, comprehensive studies must be done to determine the best choice of the tapering frequency as a function of the binary's properties. We also carry out an analysis on the binary neutron-star event GW170817 to set bounds on the coupling constant $alpha_0$ of Jordan-Fierz-Brans-Dicke gravity. We take two plausible approaches. They provide slightly different bounds, namely, $alpha_0 lesssim 2 imes 10^{-1}$ and $alpha_0 lesssim 4 imes 10^{-1}$, respectively, at $68\%$ credible level. These differences arise mainly because the tidal parameters have to be treated differently in the theory-indepdendent and theory-specific approaches. This poses a conceptual problem in tests of GR. We discuss this in greater detail in the main texts (here poster!). |
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P01.00046: Modeling Equatorial EMRI Orbital Evolution using Semi-Relativistic and Teukolsky Calculations Calla I Bassett, Daniel J Oliver, Aaron D Johnson, Benjamin M Bogner, Harry T O'Mara, Daniel Kennefick As a result of radiation damping, extreme mass ratio inspirals (EMRIs) will decay from highly eccentric, long period capture orbits to eventually produce gravitational waves detectable by the proposed LISA mission not long before they reach the last stable orbit (LSO) just before plunge. Rather than rely solely on Newtonian order approximations we use a mixed approach. When the Newtonian order approach is no longer reliable, we will switch to a semi-relativistic approximation and when we get even closer to plunge switch to a Teukolsky-based code. Having developed a grid of values for flux rates at different orbital parameters, we will use interpolation to enable us to calculate a complete robust inspiral spectrum for any initial orbital parameters. |
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P01.00047: Assesing two analytic gravitational waves models for binary black hole mergers Maria C Hamilton, Dillon P Buskirk The peak in the gravitational wave (GW) signal emitted at the merger of a binary black hole (BBH) system produces the loudest signal in the detectors. Modeling such signals requires numerical relativity (NR) to account for the nonlinear physics during the collision, but computer simulations are inherently complex, costly, and affected by numerical errors. In order to bypass this problem, two analytical models for the merger have been developed: Implicit Rotating Source (IRS) and Backwards one Body (BoB). In this work, we assess the performance of those models by comparing them with numerical data, and identifying their strengths and weaknesses. Our main finding reveals discrepancies in amplitude, but overall excellent accord in frequency for the BoB model, comparable to IRS and to NR simulations, having the added advantage that it depends only indirectly on numerical data, it accounts for spin, and it offers a seamless fit with the analytical formalisms for the inspiral. By independently evaluating and testing those models, we bring evidence of their reproducibility, thus upholding high scientific standards, and enable readers to evaluate our results themselves. |
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P01.00048: Modeling Binary Compact Object Merger Events Detected by the LIGO and Virgo Gravitational Wave Observatories Kaitlyn Prokup, Andrew T Jocham, Will Schuster, Andrew Valentini, Chance Hoskinson, Rebecca Dowe In this investigation, we model multiple neutron star and black hole merger events detected in the LIGO-Virgo Collaboration. We use Kepler’s Laws and Newtonian mechanics to model an infalling system of two objects with equal masses. We predict the expected increase in frequency or “chirp” of the infalling binary and compare that to what is found in the LIGO-Virgo database. In the initial period during which the Newtonian approximation is valid, we find reasonable agreement between our model and the results from the LIGO-Virgo Collaboration, thus verifying the basic physics of the infall. We also estimate the amount of gravitational wave energy emitted during the entire process. This provides a better understanding of the nature of these merger events and why gravitational waves are emitted by these merging compact objects. |
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P01.00049: Testing a new algorithm for isometric embedding of black hole horizons Iago Braz Mendes, Robert P Owen Isometric Embedding is a classic problem in differential geometry and general relativity that involves constructing a surface in Euclidean space described by a metric tensor. The results from this problem have a long history for visualization, but are also relevant for calculating quantities like black hole mass and energy. Unfortunately, in general scenarios, this problem requires a solver capable of handling a system of strongly nonlinear and nonstandard PDEs, for which there is no generally established algorithm. We have explored a radically new approach to the embedding problem, applying it to a variety of specific test cases and confirming that the results converge as expected and agree with results obtained analytically and by other algorithms. This poster presents the results of a finite-difference-based C++ code that we have written to implement and test this novel algorithm. |
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P01.00050: Studies of relativistic rotating stars: numerics and stability tests Nishad Muhammed, Pavan Chawhan, Matt D Duez We introduce a version of the Spectral Einstein Code that can evolve coupled hydro and spacetime stably for long timescales in 2D axisymmetry. We show code test results that demonstrate long-term numerical stability. As a first application of this code version, we study the turning point criterion. Along a sequence of equilibrium uniformly rotating, isentropic stars, it has been proved that stars on one side of a turning point are secularly unstable. Efforts have been made to establish the applicability of the criterion for differentially rotating stars as well, which are expected to be produced during binary neutron star mergers. We explore the stability of stars with different rotation laws and equations of state with an aim to test how well the criterion holds for more general cases. For this, we investigate sequences of equilibria and evolve them on a dynamical timescale. |
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P01.00051: Einstein Beams: Recreating the Wave Patterns of Gravitational Lensing Enrique J Galvez, Valeria Rodríguez-Fajardo, Thao P Nguyen, Kiyan Hocek, Jacob M Freedman We recreate the optical beams of gravitational lensing in the laboratory. We use a spatial light modulator (SLM) to deflect the components of the wavefront of a monochromatic laser beam into gravitationally lensed trajectories. By suitably programing the SLM we were able to recreate all the observations of gravitational lensing plus new features that have not been observed. Our recreations include two types of observations. One type are the ray-geometric features, such as Einstein rings and arcs. The other type are the wave features, where wave interference produces optical patterns following Bessel-function shapes when the lensing object is symmetric, and more complex astroid patterns exhibiting caustics modulated by interferences when the lensing object is asymmetric (elliptical or binary). The remarkable feature of Einstein beams is that they are an intermediate case of non-diffracting Bessel beams and diffracting Gaussian beams, and thus have a pattern that is preserved upon propagation with a slow expansion. Thus, besides their intrinsic interest for investigating lensing, they may be used in optical applications. With our laboratory technique we have investigated other features that have not been seen clearly or widely in astrophysical observations, such as lensed light carrying angular momentum, self-healing and the wavelength dependence of patterns. The technique can also be used to model lensing situations that are difficult to simulate analytically or computationally. |
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P01.00052: Tall Tails of Massless Fields in Curved Spacetime Daniel Kessler, Craig Copi, Glenn d Starkman Massless fields obeying wave equations in curved spacetimes will generally propagate not only on the null cone but also within it. This is known as the “tail effect” and has been studied primarily in the context of electromagnetic and gravitational self-force. In the simplest scenario, where one point mass is responsible for all spacetime curvature and the calculations are performed in the weak field thereof, the direct detection of electromagnetic or gravitational wave tails has been argued to be difficult. However, a more recent calculation considering the weak field of an extended matter distribution suggests that gravitational tails may be imminently detectable, which would enable the realization of GRAvitational Detection And Ranging (GRADAR) for the mapping of compact matter, perhaps to unprecedented distances. To assess the generality of this finding beyond the very symmetric special case in which it was obtained, we calculate the scalar and electromagnetic wave tails directly “backscattered” from an extended body en route to a calculation of the gravitational wave tails produced in a similar manner. |
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P01.00053: PARTICLES AND FIELDS
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P01.00054: Deep Learning Techniques for Event Reconstruction at ATLAS Xiaohan Zhu, Quentin Buat The identification and energy calibration of pions are two fundamental tasks in the reconstruction of jets generated by proton-proton collisions at A Toroidal LHC Apparatus (ATLAS). In this poster, I will present novel approaches using deep learning models for these tasks. The results will be based on the recent developments of graph neural networks with data from calorimeter clusters and tracks in the form of point clouds. The discussion includes two main topics: the use of Mixture Density Networks as an additional deep learning layer, and the generalization of existing networks for calibrating ρ and Δ resonance decays. These are critical steps towards a computer vision approach for ATLAS event reconstruction. |
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P01.00055: Logistics of High Throughput Data Transfer in High Energy Physics Orgho Neogi, Jane Nachtman High Energy physics analysis requires a large amount of data, which is increasing at an ever faster pace. Often this data is not stored at the computing resource where it is meant to be processed especially when there is a need for GPU's due to usage of machine learning, leading to a need for fast, robust and reliable methods of data transfer. Existing methods range from scp which has the advantage of being simple to configure and transfer, to GLOBUS which allows for optimization of system resources. This poster compares the various methods for various use cases. |
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P01.00056: AutoDQM Tool for CMS Data Certification Chosila Sutantawibul, Chad Freer, Andrew Brinkerhoff, Indara Suarez, Kaitlin Salyer, Vivan Nguyen, John P Rotter, Robert White, Samuel May
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P01.00057: Alignment Strategy for the Tracking Stations of FASER David Lai, Ali Garabaglu, Ke Li, Shih-Chieh Hsu The ForwArd Search ExpeRiment (FASER), located 480 m downstream from the ATLAS beam interaction point, is designed to study light weakly-interacting long-lived particles (LLPs) and neutrino interactions. One of the main components of FASER, used to detect the decay products of LLPs, is the four tracking stations, each with three layers and 24 semiconductor tracker (SCT) modules. Particles leave electronic hit signals on SCT modules, and tracks reconstructed from hits are used for analysis. To exploit the excellent intrinsic resolution of the silicon microstrip detectors, high-accuracy alignment is required. A local χ2 alignment algorithm is designed and tested on both Monte-Carlo and collision data to perform software alignment on the tracking stations. By aligning the FASER tracking stations, the performance of track reconstruction from detector hits is substantially improved. Additionally, the software alignment shows promising results when compared to survey data. |
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P01.00058: Upgrades to CMS Cathode Strip Chambers' electronics with a focus on ODMB7/5s Anders G Barzdukas As the LHC prepares for the high luminosity runs (HL-LHC) all detector systems have to brace for around 5 times the LHC's nominal instantaneous luminosity. With higher luminosity the particle flux in the muon Cathode Strip Chambers (CSC) closest to the beamline is expected to quadruple from Run 2 levels. This presents two larger needs: higher bandwidths for an increased amount of data and electronics boards that can withstand high doses of radiation. To address these needs upgrades to the CSC are divided into two sections; an extensive program of primarily upgrading the front-end electronics has been accomplished during Long Shutdown 2, and remaining upgrades to the back-end boards will be installed during Long Shutdown 3. We present these planned upgrades, current state of testing, and planned installation for the CSC electronics boards. A focus of this poster will be on the Optical Data Acquisition MotherBoards (ODMBs) which collect data from anode-wire and cathode-strip boards on the CSC detector. The ODMB upgrade is for 180 boards used by parts of the CSC closest to the beamline and can support data rates of up to 50 Gb/s. |
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P01.00059: Photon Detectors for the DUNE Vertical Drift Module-0 Thomas Bruner, Jane Nachtman The Deep Underground Neutrino Experiment (DUNE) will use an intense neutrino beam starting from Fermilab (Chicago) with a Near Detector to monitor the beam and a Far Detector installed in the Sanford Underground Research Facility (SURF - South Dakota), 1300 km far away. Four 17 kt Liquid Argon Time Projection Chambers (LArTPC) will compose the Far Detector to measure and reconstruct neutrino interactions using charge and light signals from ionizing radiation. The second of the four LArTPC modules (Vertical Drift) will detect photons with the X-ARAPUCA detector concept. A full-scale prototype ("Module-0") is being constructed for testing at the CERN Neutrino Platform in the coming year. The concept, construction, and expected performance of the X-ARAPUCA detectors for Module-0 will be presented. |
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P01.00060: Diamond-based cryogenic detector for low-mass dark matter search In Wook Kim Despite significant searches for the dark matter (DM) in our universe, there is no unambiguous evidence for the existence of the DM. Current direct search experiments are focused on detecting interactions between the DM particle and the nucleus in terrestrial detectors. A huge effort is ongoing to increase the sensitivity for the low-mass DM, down to the MeV scales. Carbon-based diamond crystals are especially suited for this purpose as they are made of light nuclei. In particular, they have gained interests from the cryogenic detection community for their cryogenic properties. Long electron-hole pair lifetime in the diamond crystal may allow the discrimination of the desired nuclear recoil signatures from the electron recoil background, which would enable a background reduction in the sub-eV region to the unpreceded level. In this talk, we present the test results from a MMC-based cryogenic detector equipped with a diamond absorber and compare with the results from the same setup with a sapphire absorber. |
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P01.00061: Module Assembly Using Robotized Gantry for the CMS Endcap Timing Layer Ohannes Kamer Koseyan, Artur Apresyan, Caleb Fangmeier, Christopher Madrid, Yasar Onel The High Luminosity LHC (HL-LHC) will deliver an instantaneous luminosity of 5×10^34 cm^-2s^-1, with an expected total integrated luminosity of 3000 fb^-1 by the end of the decade. To fully exploit these new conditions, the CMS detector will need a completely new timing detector featuring higher radiation tolerance and timing capabilities. With this new timing detector, which will be installed during the CMS Phase II upgrade, the CMS will have the ability to measure the production time of a minimum ionizing particle (MIP) precisely. This will help resolving the pileup of nearly simultaneous 200 collisions per bunch crossing. The timing detector will consist of two sub-detectors, the Barrel Timing Layer and the Endcap Timing Layer (ETL). The ETL will be the first generation, fully silicon based, subsystem covering the high eta region. It utilizes Ultra-Fast Silicon Detectors (UFSDs) based on the Low Gain Avalanche Diode (LGAD) technology [1]. A robotized gantry will be used at Fermilab during the assembly of the ETL modules that house the sensor and the first stage of data acquisition. With a relative precision on the order of 10 μm for the placement of the components, the robotized gantry will be critical in achieving the quality needed for the roughly 7000 modules that are planned for the assembly. Once the critical components are placed in the module, each module will then be mechanically examined before being transferred to the wire bonder, which proves the electrical connections within the module. After wire bonding, the gantry is used again to affix a ceramic cover plate to the sensor side of each module. The cover plate results in sturdy individual modules that can be carried around and handled without concern of damaging the most critical components, as well as providing a thermal pathway for the modules. I will present the work I have done to prepare the robotized gantry. This work includes programming and troubleshooting issues as well as optimizing the module assembly procedure. So far, we have assembled dummy modules to measure and improve the performance of the gantry which paves the way for prototype module assembly. [1] CMS Collaboration, "A MIP Timing Detector for the CMS Phase-2 Upgrade", CERN-LHCC-2019-003; CMS-TDR-020 |
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P01.00062: Identification of optimal production channels for a dark photon search at CMS F Dean B Cianciolo Production of dark photons with GeV-scale mass is predicted in many dark sector models. A distinctive signature is the presence of two pairs of oppositely charged leptons (muons only, in this study) where the angle between the leptons in a pair is small but detectable. We performed a literature survey of dark photon production mechanisms and implemented them in PYTHIA, then evaluated the results in terms of the separation and transverse momentum of the decay products of the dark photons. The results allow us to set useful cuts for a Run III analysis at CMS. |
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P01.00063: Experimental signatures of muons originating in dark matter annihilations occurring in the Earth's crust Matthew Bellis, Josephine Swann Some dark matter models of WIMPs (Weakly Interacting Massive Particles) suggest that these particles can interact with the Earth, losing enough kinetic energy such that they become gravitationally bound. Over time, the Earth could accumulate enough dark matter and anti-dark matter that annihilations to dark photons occur at some rate. These dark photons could then mix with our standard model photons and then couple to fermions, specifically muons for the purposes of this study. We explore what the energy spectrum of these muons coming up from the Earth would be and how this spectrum might differ from a background of muons originating in galactic neutrino interactions. We have built computational tools to simulate the energy loss as these muons travel through the Earth's crust and we use these tools to explore whether or not a signal could be distinguished from background, given a detector like CMS configured to look for upward-traveling muons. The current status of this study will be presented. |
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P01.00064: Low Energy Cross-Calibration of the Hyper-Kamiokande Far Detector Using a Deuterium-Tritium Neutron Generator (DTG) RAFIK ER-RABIT, Mohamed Gouighri, Thomas Kutter Hyper-Kamiokande is an international next-generation neutrino experiment currently constructing the biggest detector of its kind; Hyper-Kamiokande Far Detector (Hyper-K) in Japan. The 68m diameter, 71m height cylindrical underground water Cherenkov detector is foreseen to start taking data in 2027 and needs to be calibrated periodically for optimal performance. The primary low energy calibration system will be an electron linear accelerator (LINAC); However, this method suffers from some limitations, namely the anisotropy of the electron beam, the existence of beam pipe while taking data, the limited number of positions where it can be deployed, and it takes a relatively long time to complete the whole process. A DT Generator is used to cross-calibrate the low energy by generating an N16 cloud via (n:p) reactions on O16 after lowering it into numerous positions inside the water tank, the unstable N16 isotope will beta decay isotropically into well-known products and with a half-life of 7.13s allowing us to raise our DTG above the N16 cloud to reduce the optical shadowing of the source before data taking. The N16 could generation and decay are simulated with GEANT4, then the outputs will be propagated through the volume of the detector using the WCSim program (also GEANT4 based). LINAC and DTG were used in the past to calibrate the low energy of Super Kamiokande detector, and they will also be used for Hyper-K. |
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P01.00065: Eos: DAQ and Slow-control Systems of a Hybrid Detector Dylon A Fleming Eos is a collaboration of twenty-four institutions and will be built at Lawrence Berkeley National Laboratory . The EOS detector is an R&D platform designed to combine scintillation and Cherenkov light, two neutrino detection methods. This hybrid technology will allow future neutrino detectors to search across a broader range of the energy spectrum. Detection of neutrinos allows us to study hidden aspects of the universe using electromagnetic measurements. This is true for such things as the inside of our Sun, planet, or galactic center. The California State University Stanislaus group is contributing to the development and deployment of the Eos Data Acquisition (DAQ) and Slow Control Systems (SCM). Results from Eos will guide the development of large-scale low background neutrino observatories such as Theia, which is currently in the design phase. This hybrid technology will give future neutrino detectors greater sensitivity across a spectrum of neutrino energy and increase signal to background ratio for time-based particle identification. |
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P01.00066: Status of the muon neutrino charged-current mesonless cross section measurement in the NOvA near detector Sebastian Sanchez Falero NOvA is a long-baseline accelerator neutrino experiment at Fermilab whose physics goals include precision neutrino oscillation as well as cross-section measurements. We present the status of the measurement of muon neutrino charged-current cross section with zero mesons in the final state at the NOvA near detector. This measurement will be made with respect to the kinematics of the final state particles. Our chosen interaction channel is especially sensitive to quasielastic and meson exchange current interactions and will provide a handle for constraining the cross section systematic uncertainties in oscillation analyses in current and future experiments. For particle identification, we use a convolutional neural network (CNN) trained on individual particles simulated in the NOvA near detector that allows us to select the desired signal while reducing the potential bias from neutrino interaction modeling. Charged pion background constraining is further improved via Michel electron tagging. |
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P01.00067: Consciousness from Human's Mind to the Cosmos Hassan Gholibeigian, Zeinab Gholibeigian More than eight hundred of the two clefts’ experiments which have been done in different universities and laboratories show that the fundamental particles (FPs) are conscious. This consciousness is in a preliminary level of quality because the matter’s informational potentials (minds) of cosmos’ FPs are on and active [H.Gholibeigian, Z. Gholibeigian, APS.L027.2015]. But the human’s consciousness is at its highest level of quality because his/her FPs’ mind is on and active [H.Gholibeigian, Z. Gholibeigian, APS.L027.2015]. On the other hand, the human’s structure—like an atom and other subjects— is constituted by two wavy-like geometries (quantum fields): the first; quantum field of his/her FPs, and the second; quantum field of the minds of those FPs like a three-dimensional hologram which we call it the “human’s mind”. Processed information (qubits) of the human’s FPs is stored permanently within FPs—from Big Bang until now—and also on the boundary surface of this hologram. The human’s hologram acts as a sub-hologram of the Universe’s hologram and transmits the processed information to its boundary surface. Therefore, the cosmos that hosts us and has an evolutionary arrow inherent is always along with the final humans’ consciousness and uses it in its continuous evolution processes. |
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P01.00068: Chaotic Behavior of Perturbed Conformal Field Theories Alexandra Miller, Curtis T Asplund, David Ramirez Chaos in quantum systems has historically been challenging to quantify. One measure of the strength of chaos is the Lyaponov exponent λL. Previously, λL has been found for certain quantum field theories by analyzing out-of-time ordered four point functions. While this procedure is helpful for certain systems, performing this computation is generically quite challenging. Recently, progress has been made in extracting λL from the two-point function of the energy density operator. Specifically, one determines the exponent by finding special points where poles are skipped (where a zero in the denominator is balanced by one in the numerator). This procedure has been fruitful in holographic (gauge/gravity duality) systems as well as in SYK models. In this work, we start by considering two-dimensional conformal field theories. We then perturb away from the conformal point and analyze what happens to this pole-skipping phenomena. In this way, we track how the chaotic behavior of the system changes after a perturbation to a more general class of theories. |
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P01.00069: Production of the Asymmetric Dynamical Casimir Effect Due to Time Dependent Delta Derivatives and Time Dependent Asymmetric Robin Boundaries William Julius, Matthew Gorban, Ramesh Radhakrishnan The imposition of asymmetric boundrary conditions on a fluctuation mirror result in the production of an asymmetric (between the sides of the mirror) spectrum of particles. This is the asymmetric dynamical Casimir effect (ADCE). Here we present a novel form of producing this effect in a (1+1)D δ-δ' model by modifying the coefficient of the δ' term to be time dependent. We see this modification leads asymmetric spectra similar to those seen by the typical modification of the plasma frequency, leading to the same induced motion identified in other systems undergoing the ACDE. We also examine the production of the ADCE due to the introduction of time asymmetry into a time dependent Robin boundary. This also leads to an asymmetric production of particles on either side of the boundary, with resulting induced motion. |
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P01.00070: Constraining strong gravity using rare semileptonic B meson decays Nathaniel Alden, Roberto Onofrio We explore a scenario in which strong gravity could be responsible for modifying the momentum of muons and electrons produced in semileptonic B meson decays. Strong gravity is parameterized with a Yukawa potential reproducing usual gravity in the macroscopic world, but with much stronger coupling at short distances. Recent experimental data allows us to constrain the strength of strong gravity, and to make predictions for other decay rates, most notably the B-meson decays into tau-lepton pairs. |
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P01.00071: Search for Higgsinos in Compressed Mass Spectra using Neural Networks in $sqrt{s} = SI{13}{TeV}$ $pp$ Collisions with the ATLAS Detector Sicong Lu Super-symmetric extensions of the Standard Model featuring Higgsinos with compressed mass spectra and masses near the electroweak scale may solve the hierarchy problem. These models provide a higgsino-like neutralino as a Dark Matter candidate that can also be consistent with current cosmological evidence. |
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P01.00072: UV Freeze-in Leptogenesis via Dark Matter Oscillations Tian Dong, Coleman Gliddon, Derek J Li, Brian Shuve, David Tucker-Smith Models of freeze-in dark matter (DM) allow for the generation of the observed baryon asymmetry through the production, oscillation, and annihilation of DM particles. In contrast with earlier studies which have focused exclusively on IR-driven freeze-in of DM, we perform the first study of leptogenesis via UV freeze-in. We introduce two DM fermions and two scalars of different masses to consider two models of leptogenesis: in the mixed UV-IR model, DM freeze-in occurs via both decays of the lighter scalar and scattering of SM particles with a heavy virtual mediator; in the fully UV model, DM is produced only through scattering. Perturbatively solving the quantum kinetic equations, we find parameters consistent with the observed baryon asymmetry and DM abundance in both models; however, the fully UV scenario has a much narrower window of viable parameters. Our results afford points of comparison for understanding the different dynamics of IR and UV leptogenesis and point toward tests for their experimental verification. |
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P01.00073: Identification and estimated yield of background events in a search for a doubly charged Higgs boson at CMS Zhengyu J Pan A variety of exotic models predict a doubly charged Higgs-like particle that can be pair-produced in hadronic interactions via a Drell-Yan-like mechanism. The H++ and H-- can each decay to a pair of like-sign leptons (muons or electrons in this study) with TeV-scale mass, providing a distinctive event signature. The small background makes it challenging to predict it well. We studied Monte Carlo events to determine the source of background events and construct a background estimate from the results. |
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P01.00074: Search for Neutral Long-lived Particles Decaying in the CMS Muon Detectors with Run3 Paul W Simmerling, Christina Wang, Si Xie, Cristián Peña, Maria Spiropulu Many searches for beyond the standard model (SM) physics predict the existence of "long-lived particles" (LLPs). These LLPs are neutral, weakly-coupled, and have a long lifetime. Moreover, LLPs often have large displacement signatures allowing them to go undetected in conventional searches for prompt particles and thus remain largely unexplored at the LHC. We present an extension of a previous search at the LHC that used the CMS muon detectors (MD) as a sampling calorimeter capable of detecting displaced showers produced by LLP decays. The MD are composed of detector planes interleaved with the steel layers of the magnet flux return yoke. Decays of LLPs in the MD induce hadronic and electromagnetic showers, giving rise to a high hit multiplicity in localized detector regions that can be efficiently identified with a novel reconstruction technique. Additionally, the steel layers allow for exceptional background shielding from the SM which dominates existing LLP searches. This search is largely model-independent, can detect LLP masses as low as a few GeV, and is sensitive to many final states including hadrons, taus, electrons, and photons. Starting in Run3, a new high level trigger was developed for LLP searches allowing for a higher event rate and access to a larger kinematic regime. Using a partial dataset from Run3 and the new trigger, we present a sensitive measurement of the LLPs proper lifetime from 0.1m to 1000m. |
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P01.00075: FACET: Forward Aperture CMS ExTension for LLP Searches Hazal M Zenger, Jane Nachtman The FACET project to search for Beyond the Standard Model long-lived particles at the LHC is being developed as a new very forward subsystem of CMS. Located 100 - 120 m from the CMS collision point it will be sensitive to particles that can penetrate up to 50 m of iron absorber and then decay in a vacuum tank approximately 1 m diameter and 12 m long to standard model particles. These are measured in silicon tracking, calorimeters and a toroidal muon spectrometer using CMS Phase-2 upgrade detector technology. FACET has sensitivity to dark photons, heavy neutral leptons, axion-like particles and dark Higgs bosons in a unique region of mass and coupling strength. |
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