Bulletin of the American Physical Society
2019 Joint Fall Meeting of the Texas Sections of APS, AAPT and Zone 13 of the SPS
Volume 64, Number 18
Friday–Saturday, October 25–26, 2019; Lubbock, Texas
Session E02: Nuclear & Particle II |
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Chair: Andrew Whitbeck, Texas Tech University Room: Student Union Building Mesa Room |
Friday, October 25, 2019 1:30PM - 2:06PM |
E02.00001: Recent results on searches for physics beyond the Standard Model at the LHC and future outlook Invited Speaker: Kenichi Hatakeyama The Higgs boson discovery by the CMS and ATLAS experiments at CERN was a major milestone for particle physics and marked another success of the standard model, our current best theory for elementary particles. In this talk, I will discuss the implications of the Higgs discovery and our endeavor to shed light on the nature of the dark matter and gauge hierarchy problem through searches for supersymmetry using the data collected with the CMS detector at the Large Hadron Collider (LHC). A novel experimental technique has been developed for these searches. I will also discuss our effort to upgrade the CMS detector systems for future data taking and physics potentials with the upgraded detector. [Preview Abstract] |
Friday, October 25, 2019 2:06PM - 2:18PM |
E02.00002: Search for supersymmetry in events with photon, jets, b bets and missing transverse energy Vinay Hegde The standard model (SM) of particle physics successfully explains many of the phenomena around us. But it cannot explain gravity, existence of dark matter, matter anti-matter asymmetry, Higgs mass being much lower than the Planck scale etc. Supersymmetry is an extension of the SM, which may provide solutions to some of the issues with the SM. A search for supersymmetry is presented based on events with at least one photon, light flavor jets or b jets, and large missing transverse momentum produced in proton-proton collisions at a center-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of $35.9 fb^{-1}$ and were recorded at the LHC with the CMS detector in 2016. Since no significant excess of events is observed with respect to the expectations from standard model processes, limits are placed on the pair production cross-sections of gluinos and top squarks. Depending on the model and the mass of the next-to-lightest supersymmetric particle, the production of gluinos with masses as large as 2120 GeV and the production of top squarks with masses as large as 1230 GeV are excluded at 95\% confidence level. [Preview Abstract] |
Friday, October 25, 2019 2:18PM - 2:30PM |
E02.00003: Search for VBF production of heavy resonances decaying to Z(nunu)W/Z(qqbar) final state Kamal Lamichhane A search for heavy resonances decaying to a pair of vectors bosons is presented which utilizes events in which a hadronically decaying Z or W boson is identified using jet substructure techniques and large missing transverse momentum is found. Data analyzed were recorded by the Compact Muon Solenoid experiment at the CERN Large Hadron Collider in 2016, 2017, and 2018, and correspond to 137 fb-1. The events are categorized as having arisen from Vector Boson Fusion process or not, and are characterized by their transverse mass distribution. The standard model backgrounds are estimated based on observed yields in control regions. No excess of events above the expected SM background are observed and limits are placed on the production cross section of Radion (spin-0), Wprime (spin-1) and Bulk graviton (spin-2) particles. [Preview Abstract] |
Friday, October 25, 2019 2:30PM - 2:42PM |
E02.00004: Study of the Kinematics of the Process $H^0 \to gg \to b\overline{b}b\overline{b}$ at the Large Hadron Collider with the ATLAS Experiment Jared Burleson, Stephen Sekula, Rebecca Moore This report concerns a summary of the work done during our summer research project. This report is a condensed analysis of the kinematic study of the characteristics of simulation models that represent expected detection elements produced by the ATLAS Experiment at the Large Hadron Collider, LHC. The analysis of the data was done primarily through the programming language python and its data science library classes. This study is done primarily to show that the identification of a particular Higgs process is incredibly difficult when considering other background processes that could be interpreted as false-positives in an isolated analysis. From our analysis of the kinematics of these processes, we also explore the beginnings of training a machine-learning algorithm, through one of python's machine-learning libraries, to distinguish Higgs processes based on the kinematic data available to a detection model. The purpose of this study is to demonstrate the potential capability of a collider experiment in searching for the process $H^0 \to gg \to b\overline{b}b\overline{b}$. [Preview Abstract] |
Friday, October 25, 2019 2:42PM - 2:54PM |
E02.00005: Multiplicity distributions from heavy-ion collisions at the Large Hadron Collider Negin Alizadehvandchali Collisions of relativistic heavy-ions at the Large Hadron Collider (LHC) are carried out in order to create a unique state of matter known as the Quark Gluon Plasma (QGP). In this state, hadronic matter melts, and quarks and gluons become the relevant degrees of freedom. It is believed that the universe temporally existed in such a state shortly after the big bang. The distribution of produced charged particles (multiplicity) provides critical information regarding the initial state of these collisions. I will present the latest multiplicity distributions measured by the ALICE collaboration at the LHC. I will discuss comparisons of these distributions to theoretical models, and detail future plans regarding new measurement techniques. [Preview Abstract] |
Friday, October 25, 2019 2:54PM - 3:06PM |
E02.00006: Thermal Fits to Hadron Yields in ALICE and STAR Gabrielle Olinger, Fernando Flor, Rene Bellwied The Statistical Hadronization Model (SHM) has been tested to adequately reproduce hadronic particle abundances over nine orders of magnitude in high energy collisions of heavy ions. Experimental particle yields at RHIC and the LHC are used in determining freeze-out parameters of the QCD phase diagram via thermal fits in the SHM framework. When comparing extracted freeze-out parameters obtained using different sets of particles in the thermal fit, differences in the chemical freeze-out temperature arise between light and strange hadrons. In this talk, I will show recent calculations of freeze-out parameters using particle yields from STAR and ALICE collisions at $\sqrt{s_{NN}}=$ 7.7 GeV - 7.0 TeV. Using the Grand Canonical approach within the Thermal FIST HRG model, I will show evidence for a flavor-dependent freeze-out in the QCD crossover region and compare to lattice calculations. Lastly, I will compare the quality of fits across various treatments of strangeness conservation under different freeze-out conditions. With the same approach applied to pp and pPb collisions, I will show that the SHM is applicable to small systems and that flavor dependencies in the freeze-out parameters lead to a natural explanation of strangeness enhancement from small to large systems. [Preview Abstract] |
Friday, October 25, 2019 3:06PM - 3:18PM |
E02.00007: QCD Equation of State From Holographic Black Holes. Joaquin Grefa, Jorge Noronha, Jacquelyn Noronha-Hostler, Israel Portillo, Claudia Ratti, Romulo Rougemont By using the holographic gauge/gravity correspondence, we construct a family of five-dimensional black holes to map the thermodynamics of Quark-gluon matter. The black holes are constrained to mimic the equation of state from lattice QCD at vanishing chemical potential. This model, which reproduces the crossover region in the QCD phase diagram and predicts a line of first order phase transition with a critical end point, provides a QCD equation of state from which baryon susceptibilities can be computed. [Preview Abstract] |
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