Bulletin of the American Physical Society
2017 Annual Meeting of the Far West Section
Friday–Saturday, November 3–4, 2017; Merced, California
Session F2: Gravitation and High Energy Physics |
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Chair: Roland Winston, University of California Merced Room: COB2 266 |
Friday, November 3, 2017 2:00PM - 2:12PM |
F2.00001: Using a PID Feedback Loop to Correct Apparatus Tilt via Thermal Expansion Noah Dunkley, Charles Hoyle Theories which attempt to unify the Standard Model and General Relativity often include features which violate the Weak Equivalence Principle (WEP) and gravitational Inverse-Square Law (ISL). A violation of either the WEP or ISL at any length scale would bring into question our fundamental understanding of gravity. Motivated by these considerations, undergraduates and faculty at Humboldt State University are building an experiment to probe gravitational interactions below the 50-micron length scale. One challenge that the experiment faces is the daily tilt variation of the building that houses the experiment. This changes the separation of the pendulum with respect to the other experimental components, thereby introducing potential systematic uncertainties. This problem was corrected the implementation of a feedback system that thermally expands the support leg of the apparatus to maintain its level throughout the course of data acquisition. The associated potential systematic uncertainties have been reduced by roughly a factor of five with this system. [Preview Abstract] |
Friday, November 3, 2017 2:12PM - 2:24PM |
F2.00002: A New Experiment to Measure G Hilde Isachsen, Ricardo Decca, C.D. Hoyle Of all the fundamental constants of nature, G, the universal gravitational constant, is known with the least precision. The world's best experiments yield values which are incompatible with one another and differ by about 40 times the uncertainty of the most precise experiment. Since part of the past discrepancies between determinations of G can be traced back to the methodology used, the research group at IUPUI in collaboration with Humboldt State University and Syracuse University will combine different approaches to determine G within the same torsion pendulum apparatus, hoping to obtain highly precise values of G from each approach. With the experiments carried out in the same apparatus, the effort will also help to understand the current discrepancies among existing experimental results. In addition to this discussion, this talk will also cover work done during my summer internship at IUPUI with PI Ricardo Decca, including error evaluation related to experimental design and initial construction of the enclosure that will keep the temperature and humidity constant around the apparatus. [Preview Abstract] |
Friday, November 3, 2017 2:24PM - 2:36PM |
F2.00003: Novel Tests of Gravity Below Fifty Microns Anthony Sanchez, Noah Dunkley, Nicholas Hernandez, Gabriela Martinez, Hilde Isachsen, Jeremy Johnson, Zane Coden, Duncan Shaw, Charles Hoyle The effort to unify the Standard Model and General Relativity often involves theories which contain features that may violate the Weak Equivalence Principle (WEP) and gravitational Inverse-Square Law (ISL). A violation of either the WEP or ISL at any length scale would bring into question our fundamental understanding of gravity. Undergraduates and faculty at Humboldt State University are running an experiment to probe gravitational interactions below the 50-micron length scale. The experiment employs a torsion pendulum with equal masses of different material arranged as a `composition dipole.' The experiment measures the twist of the torsion pendulum as an attractor mass is oscillated nearby in a parallel-plate configuration, providing a time varying torque on the pendulum. The size and distance dependence of the torque variation will provide a means to determine any deviation from the WEP or ISL at untested scales. This talk will focus on the current state of our experiment and we will cover several updates to our equipment, models and recent data taken in the lab. [Preview Abstract] |
Friday, November 3, 2017 2:36PM - 2:48PM |
F2.00004: Analysis of $\pi^0$ spectra from the 5 TeV p-Pb ALICE run Ivan Chernyshev This work examined the $\pi^0$ spectra of the data collected during the 5 TeV p-Pb run in 2013 at the ALICE detector at the Large Hadron Collider in CERN. The $\pi^0$ data is constructed via its diphoton decay. The data are split into 5 pT intervals ranging from 6 GeV to 16 GeV and given several cuts along various parameters, such as photon electromagnetic shower shape, asymmetry of the decay, and several quality variables. It is then analyzed with a variety of fit methods, notably fitting to a Gaussian peak + second-order polynomial background model. The conclusions derived from this analysis, most notably $\pi^0$ mass, signal-to-noise ratio, and effects of various cuts to the data, will then be used for various purposes in the context of $\pi^0$ analysis with ALICE data, most notably helping to train neural networks to identify photons. [Preview Abstract] |
Friday, November 3, 2017 2:48PM - 3:00PM |
F2.00005: Higgs-like effect and particle production induced by gravitational wave background Douglas Singleton, Patrick McDougall, Michael Ragsdale, Preston Jones We show that a {\it massless} scalar field in a gravitational wave background can develop a non-zero and space-time dependent vacuum expectation value. We draw comparisons to the generation of a non-zero vacuum expectation value for a scalar field in the Higgs mechanism and with the dynamical Casimir vacuum. This gravitational wave generated vacuum expectation value can be connected to particle production from gravitational waves and may have consequences for the early Universe where scalar fields and their vacuum values are thought to play an important role. [Preview Abstract] |
Friday, November 3, 2017 3:00PM - 3:12PM |
F2.00006: Magnetic Charge and Photon Mass Timothy Evans, Douglas Singleton In this talk we study magnetic charge in the presence of a photon mass and find very simple and physical potentials and fields. Several properties of magnetic charge with a photon mass differ markedly from magnetic charge with a massless photon: (i) the string singularities of the two, usual 3-vector potentials become real singularities in the magnetic fields; (ii) the two 3-vector potentials become gauge inequivalent and physically distinct solutions; (iii) the magnetic field depends on the axial angle and is no longer rotationally symmetric; (iv) a combined system of electric and magnetic charge carries a field angular momentum even when the electric and magnetic charges are located at the same place; (v) the usual Dirac quantization condition is altered. Given the reality of the string singularity the only way to ``hide" the string is to require a QCD-like flux tube confinement between opposite magnetic charges {\it i.e.} magnetic charge, like color charge, should always be confined. [Preview Abstract] |
Friday, November 3, 2017 3:12PM - 3:24PM |
F2.00007: Scalar Dark Earth-Shine Adam Green, Flip Tanedo Dark matter may interact with itself and with ordinary matter through new forces with new mediator particles. We extend the work of a recent study of the dark photon mediator to a spin-0 scalar mediator, the dark Higgs. In this scenario, dark matter collects in the center of the earth and annihilates into these mediators which could decay into detectible particles near the surface of the Earth. In the annihilation rate, we include Sommerfeld enhancements, which play a critical role in decreasing the timescale for the capture-annihilation process to equilibrate. We also highlight the importance of the s-wave 2-to-4 annihilation in the dark Higgs model, as opposed to the s-wave 2-to-2 annihilation in the dark photon model. This search may compliment the dark photon search by allowing for a broader distribution of signal events which point back towards the center of the earth. [Preview Abstract] |
Friday, November 3, 2017 3:24PM - 3:36PM |
F2.00008: Comparing p+p simulations with published LHC data Joshua Frandsen The goal of this project is to explore one method to measure the properties of a fundamental state of matter that is formed at particle colliders known as the quark gluon plasma, utilizing data measured by the ALICE Collaboration at the CERN Large Hadron Collider. We utilize the well-understood phenomenon of jets, which are remnants of scattered quarks and gluons generated in high energy collisions of all kinds. In particular we utilize the interaction of such jets with quark gluon plasma. There are multiple methods for measuring such interactions, in this study we focus on the coincidence measurement of a high energy photon and its recoiling jet, an observable known as $\gamma + jet$. In order to determine if this channel can be measured using experimental data recorded by ALICE, simulations of collisions are carried out under conditions that match the real recorded data. However, validation of these predictions requires calibration of the simulation tools against other published measurements. This paper reports such a calibration for the PYTHIA event generator, by comparing simulated results to experimental data measured at the Large Hadron Collider. [Preview Abstract] |
Friday, November 3, 2017 3:36PM - 3:48PM |
F2.00009: Probing Cosmic Evolution: Long Term Analysis of 1ES 1215$+$303 Trenton Rosenquist In February of 2014 (MJD 56696), the blazar 1ES 1215$+$303 underwent a flare reaching a peak flux of 2.4 Crab at energies over 100 GeV. To examine the spectral properties of the source, an energy spectrum was reconstructed for the night of the flare, along with a long-term light curve to examine the flux of very-high-energy gamma rays over the entirety of observations between 2008 and 2016. The results suggest the source underwent spectral hardening, with a spectral index of 3.02 \textpm 0.07 for the night of the flare and 3.47 \textpm 0.15 during the low state of the source. I will share the VERITAS results in the context of what it means to the gamma-ray production at work within the source, and discuss the implications of these results for future work to constrain the extragalactic background light. [Preview Abstract] |
Friday, November 3, 2017 3:48PM - 4:00PM |
F2.00010: A New Approach to Detecting Gravitational Waves via the Coupling of Gravity to the Zero-point Energy of the Phonon Modes of a Superconductor Nader Inan The response of a superconductor to a gravitational wave is shown to obey a London-like constituent equation. The Cooper pairs are described by the Ginzburg-Landau free energy density embedded in curved spacetime. The lattice ions are modeled by quantum harmonic oscillators characterized by quasi-energy eigenvalues. This formulation is shown to predict a dynamical Casimir effect since the zero-point energy of the ionic lattice phonons is modulated by the gravitational wave. It is also shown that the response to a gravitational wave is far less for the Cooper pair density than for the ionic lattice. This predicts a “charge separation effect” which can be used to detect the passage of a gravitational wave. [Preview Abstract] |
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