Bulletin of the American Physical Society
2018 Joint Fall Meeting of the Texas Sections of APS, AAPT and Zone 13 of the SPS
Volume 63, Number 18
Friday–Saturday, October 19–20, 2018; University of Houston, Houston, Texas
Session K01: High Energy and Particle Physics III |
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Chair: Carlos Ordonez, University of Houston Room: Science and Engineering Classroom (SEC) 101 |
Saturday, October 20, 2018 10:00AM - 10:24AM |
K01.00001: Using Jets to Probe the Quark Gluon Plasma Invited Speaker: Saskia Mioduszewski Accelerating and colliding heavy ions at very large energies provides a laboratory for studying nuclear matter under extreme conditions. Under such conditions, the matter is expected to undergo a phase transition, “melting” the protons and neutrons into their fundamental constituents, quarks and gluons (or partons). To study the properties of this Quark Gluon Plasma (QGP) phase, we need “probes” that carry information about the properties of the produced matter. Ideally, such probes are created early in a heavy-ion collision, allowing them to experience the full evolution of the collision, including the hottest and densest phases of the matter. Jets, which are collections of particles resulting from scatterings of energetic partons with large momentum transfer (“hard scatterings”) upon initial impact of the incoming nuclei, are among such probes. In-medium modifications of jets are quantified by comparing jet production in heavy-ion collisions to the baseline measurement in proton+proton collisions. In some hard scatterings, a photon is produced back-to-back with a jet. Direct photons, those produced during the collision rather than from decays of hadrons, are of interest because they do not interact strongly and thus are not affected significantly by the medium. With the photon energy as a good approximation for the initial energy of the recoil parton (before interaction with the medium), the study of direct-photon-tagged jets can give information about the energy loss of the recoil parton while traversing through the medium. Recent measurements of jets and photon-tagged jets will be presented and discussed. |
Saturday, October 20, 2018 10:24AM - 10:36AM |
K01.00002: QCD phase diagram with a critical point from holographic black holes Israel Portillo We use the gauge/gravity duality to map thermodynamic fluctuations of black holes onto fluctuations of baryon charge in a hot and baryon dense Quark-Gluon Plasma (QGP). Our approach gives results that are in quantitative agreement with state-of-the-art lattice simulations for the QCD equation of state at finite baryon density and fluctuations of baryon charge, while simultaneously encompassing nearly-perfect fluidity. This framework provides a definite prediction for the QCD critical point, which is found to be within the reach of low collision energy experiments at RHIC and also the CBM experiment at FAIR. |
Saturday, October 20, 2018 10:36AM - 10:48AM |
K01.00003: Rotating traversable wormholes in AdS Anderson S Misobuchi, Elena Caceres, Ming-lei Xiao Traversable wormholes can be obtained via a double trace deformation coupling the two boundaries of an asymptotically Anti-de Sitter (AdS) eternal black hole. In this work we construct a traversable wormhole with angular momentum. We show how the double trace deformation introduces negative energy into the bulk geometry violating the Averaged Null Energy Condition (ANEC). We find that at fixed temperature the wormhole opening increases with the angular momentum. The amount of information that can be sent through the wormhole increases as well. However, for the type of interaction considered, the wormhole closes as the temperature approaches the extremal limit. |
Saturday, October 20, 2018 10:48AM - 11:00AM |
K01.00004: A test of holographic complexity = purification complexity. Elena Caceres, Josiah D Couch, Stefan V Eccles, Willy Fischler A conjectured entry into the AdS/CFT dictionary relates the circuit complexity of a boundary state to either the action on the bulk Wheeler-DeWitt patch or a maximal volume bulk slice homologous to the boundary slice. If one or both conjectures are correct, there is a plausible generalization to a duality between the same bulk quantities computed on entanglement wedges of boundary subregions, and the mixed state complexity on those subregions. However, there is no unique extension of pure state complexity to mixed state complexity. One version of this conjecture uses the “purification complexity” as a measure of mixed state complexity. We test this conjecture in the context of multi-sided eternal black hole solutions, including three-dimensional black holes with arbitrary genus in the behind-the-horizon region. We find that neither the subregion action nor subregion volume behaves entirely as expected in all contexts, suggesting that the proposal should be modified or abandoned. |
Saturday, October 20, 2018 11:00AM - 11:12AM |
K01.00005: Visualizing the sensitivity of hadronic experiments to nucleon structure Bo-Ting Wang Determinations of the proton's parton distribution functions (PDFs) are emerging with growing precision due to increased experimental activity at facilities like the Large Hadron Collider. While this copious information is valuable, the speed at which it is released makes it difficult to quickly assess its impact on the PDFs, short of performing computationally expensive global fits. As an alternative, we explore new methods for quantifying the potential impact of experimental data on the extraction of proton PDFs. Our approach relies on the Hessian correlation between theory-data residuals and the PDFs themselves, as well as on a correlation newly defined quantity - the sensitivity - which reflects both PDF-driven correlations and experimental uncertainties. This approach is realized in a new available analysis package PDFSENSE, which operates with these statistical measures to identify particularly sensitive experiments, weigh their relative impact on PDFs, and visualize their distributions in a space of the parton momentum fraction x and factorization scale \mu. This tool offers a new means of understanding the influence of individual measurements in existing fits, as well as a predictive device for directing future fits toward the highest impact data and assumptions. |
Saturday, October 20, 2018 11:12AM - 11:24AM |
K01.00006: 3D𝛑 - Three Dimensional Positron Identification with Liquid Argon Total-Body TOF-PET Alejandro Ramirez, Xinran Li, Andrew L Renshaw Positron Emission Tomography (PET) is used in nuclear medicine to diagnose diseases and observe metabolic processes. However, the inefficiencies of current PET scanners limit the true potential of PET imaging. To rectify these problems, we propose 3Dπ: a full body, Time of Flight (TOF) PET scanner that employs Silicon Photomultipliers (SiPMs) coupled with a Liquid Argon (LAr) scintillator. This new design was simulated using the Geant4 simulation tool kit while following the NEMA evaluation tests to assess its performance. Along with this, we tested two variations of the LAr scintillator: LAr with Tetraphenyl-Butadiene (TPB) and LAr doped with Xenon atoms. The findings of this study indicate this new design offers a 200-fold gain in sensitivity, a timing resolution below 100ps (FWHM) and an increase in image quality. Thus, with these advantages, the patient could theoretically undergo 15-30 second scans instead of the average 30-45-minute scan. Furthermore, the dosage of the radioactive tracer ingested by patients can also be reduced and still recreate decent quality scans. In conclusion, 3Dπ offers better reconstruction of individual positron annihilation vertices and provides low-dose PET scans for patients who may be at high risk for exposure to radiation. |
Saturday, October 20, 2018 11:24AM - 11:36AM |
K01.00007: Ion Beam Systems for Barium Tagging in Neutrinoless Double Beta Decay Minh Tram The NEXT collaboration develops time projection to chambers to test whether neutrinos are their own antiparticle, via the process known as neutrinoless double beta decay. A positive signal would provide an intriguing insight to the question of how our universe came to acquire an asymmetry of matter over antimatter. Detecting such a signal requires a detection environment immune to background interference (or at least reduced it to negligible levels) from gamma rays. To achieve this, the NEXT collaboration is developing Barium tagging systems which may tag ions of barium with single molecule fluorescence imaging. I will present technical progress on the barium ion test beam developed at the University of Texas at Arlington to test this system. |
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