Bulletin of the American Physical Society
2016 Annual Meeting of the Far West Section
Volume 61, Number 17
Friday–Saturday, October 28–29, 2016; Davis, California
Session S1: High Energy and Accelerator Physics |
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Chair: Nan Phinney, SLAC National Accelerator Laboratory Room: Conference Room A |
Saturday, October 29, 2016 2:00PM - 2:12PM |
S1.00001: A collider search for Dark Matter produced in association with a Higgs boson in the four-lepton final state at the 13 TeV LHC with CMS Dustin Burns The unknown particle composition of cosmic dark matter (DM) is one of the greatest mysteries of science. In addition to direct and indirect searches, the detection of DM is attempted after its production in high energy particle colliders. The study presented here is a search for DM produced by 13 TeV proton-proton collisions at the Large Hadron Collider (LHC) using the Compact Muon Solenoid (CMS) detector. The DM escapes the detector undetected, resulting in a large imbalance of transverse momentum, which can be observed when a Standard Model particle is tagged opposite, in this case, the Higgs boson. The discovery of the Higgs boson opens a new portal to the search for DM, with a variety of models motivated by a DM-Higgs interaction, whose signatures are called Mono-Higgs. Preliminary results are shown using data collected by CMS in 2015 for the Mono-Higgs signiture with the Higgs decaying to four leptons via two Z bosons, with the continuing analysis of 2016 data outlined. [Preview Abstract] |
Saturday, October 29, 2016 2:12PM - 2:24PM |
S1.00002: Heavy Flavour Electron-Hadron Azimuthal Correlations In PP Collisions With The Alice Experiment Patrick Steffanic, Jennifer Klay In the ALICE experiment at the LHC, lead-lead collisions produce a state of matter called the Quark-Gluon Plasma(QGP), while proton-proton collisions do not. Heavy quarks(charm and beauty), created shortly after the collision, are efficient probes of the QGP properties since they experience the full evolution of the medium while interacting with its constituents. We report on electron-hadron azimuthal correlations in pp collisions at 8 TeV measured with ALICE, focusing on electrons from semi-leptonic decays of heavy hadrons. In pp collisions, QGP is not formed; studying them provides a baseline measurement for the understanding of the results in lead-lead collisions, in which QGP is created. Further plans for this analysis will be to report on electron-jet azimuthal correlations to provide a baseline for in-medium modification of heavy flavor jets produced in Pb-Pb collisions. [Preview Abstract] |
Saturday, October 29, 2016 2:24PM - 2:36PM |
S1.00003: Nanofiltration of water-based liquid scintillator for future neutrino detectors Steven Gardiner, Juan Franco, Tejas Sharath, Robert Svoboda The recent development of water-based liquid scintillator (WbLS) has generated significant interest among experimental neutrino physicists. A large-scale neutrino detector based on this material, such as the proposed THEIA experiment, would combine many of the advantages of existing water Cherenkov and oil-based scintillator detectors. In order to maintain the optical clarity of the WbLS in a large detector, one must recirculate the WbLS and remove impurities, such as metal ions, that accumulate over time. An important requirement for such a purification system is the ability to separate the organic scintillator molecules from the water and dissolved ions. The two separate streams may then be cleaned individually, remixed, and replaced in the detector. Our group has begun to investigate whether a commercially-available nanofiltration system could be used to separate WbLS organic molecules from water in a large neutrino detector. In this talk, we present results from our most recent nanofiltration tests and prospects for future WbLS nanofiltration efforts. [Preview Abstract] |
Saturday, October 29, 2016 2:36PM - 2:48PM |
S1.00004: Positive Energy Conditions in 4D Conformal Field Theory Valentina Prilepina, Markus Luty, Kara Farnsworth I will discuss a local energy condition, the spacetime averaged weak energy condition (SAWEC), in the context of conformal field theory (CFT). This condition is a bound on the energy density with spacetime averaging over a region of length scale $L$, $\langle T^{00}\rangle \geq -C/L^4$, where $C$ is a positive theory-dependent constant. We motivate this condition as a fundamental consistency requirement for any $\text{4D}$ quantum field theory. We argue that violation of this statement would have serious undesirable consequences for a theory. In particular, the theory would contain states indistinguishable from states of negative total energy by any local measurement, which would lead to unphysical instabilities. We apply the condition to $\text{4D}$ and $\text{3D}$ CFTs and derive bounds on the OPE coefficients of these theories. Interestingly, these conditions imply the positivity of the 2-point function of the energy-momentum tensor. Our $\text{4D}$ bounds are weaker than the ``conformal collider" constraints of Hofman and Maldacena, which were recently rigorously established. All calculations have been carried out in momentum-space using Wightman correlation functions. These methods may also be interesting on their own. [Preview Abstract] |
Saturday, October 29, 2016 2:48PM - 3:00PM |
S1.00005: Improving the efficiency of Cosmic Radiation Detection Jose Orozco, Jose Garcia, Stefan Ritt High energy cosmic radiation constantly surges trough the universe. In order to accurately analyze cosmic radiation precise measurements must be acquired. The equipment used to detect these particles included two micro photomultiplier (PMT) detectors, plastic scintillators, and green wavelength shifting optic fibers. In order to prove the authenticity of the electrical signals produced by the micro PMT detector several trigger settings were implemented including double, triple and quadruple coincidence. The purpose of the experiment was to explore, implement and analyze variations of the original experiment to improve both amplitude and amount of counts collected. Our research involved three main activities: 1) separation of the Micro PMT detectors to limit the arrival directions of cosmic rays 2) determining the efficiency of detecting cosmic rays at selected areas on the scintillator sheets 3) improving the efficiency with an arrangement of optical fibers based on findings from activities (1) and (2) above. [Preview Abstract] |
Saturday, October 29, 2016 3:00PM - 3:12PM |
S1.00006: Cosmic Ray Telescope Assembly and Operation Juan Ramirez Chavez, Maria Troncoso, Sewan Fan, Stefan Ritt Cosmic rays consist of particles accelerated from remote supernova remnant explosions and travel vast distances throughout the cosmos. Upon arriving at earth, the majority of them ionize gases in the upper atmosphere, while others interact with gas molecules in the troposphere and producing secondary cosmic rays, which are the main focus of this research. To observe the secondary cosmic rays, we assembled a detector telescope equipped with two silicon photomultipliers (SiPMs). Each SiPM is coupled to a bundle of 4 wavelength shifting optical fibers that are embedded inside a plastic scintillator sheet. The SiPM signals were amplified using a fast preamplifier with coincidence between detectors established using a logic AND gate. The coincidence events were recorded with two devices, a digital counter and an Arduino microcontroller. For detail analysis of the SiPM waveforms, a DRS4 digitizer captured the waveforms for offline analysis with the CERN software package Physics Analysis Workstation. Results from our experiments would be presented. [Preview Abstract] |
Saturday, October 29, 2016 3:12PM - 3:24PM |
S1.00007: Hamiltonians for Color in the Standard Model and Implications Richard Holmes A set of six 3x3 Hamiltonian matrices are identified that have eigenstates that correspond to the conventional three color and three anti-color states of QCD. Application of these matrices to the up and down quark families yields three and only three generations of flavors; and eigenvalues that accurately match the measured or inferred masses of the three flavors of particles of each quark. The eigenstates are shown to have the same properties as the color states in QCD. The 3 degenerate mass eigenstates per flavor permit a unique and accurate fit of the CKM matrix, and a physical rationale is provided. These matrices can also be applied to the lepton families, resulting in (a) an accurate match of the measured or inferred masses of the leptons; (b) an orderly pattern of the matching free parameters of the Hamiltonians for all four families of fundamental fermions; and (c) an interpretation of neutrino oscillations as superpositions of eigenstates of the Hamiltonians, and (d) a unique and accurate fit of the PMNS matrix. The theory supports pure-mass Dirac states for the electron family. Upon integration of the Hamiltonians with the Dirac equation, one finds equations invariant under TCP, Lorentz, SU(1), and SU(2)L, and SU(3) transformations. Remaining issues are discussed. [Preview Abstract] |
Saturday, October 29, 2016 3:24PM - 3:36PM |
S1.00008: Beyond the 2015 Standard Model: Specific possible elementary particles, plus phenomena they might explain Thomas J. Buckholtz We discuss a possible analog, for elementary particles, to the periodic table for elements. The analog points to specific possible elementary particles and some of their properties. The particles and some symmetries point to possible descriptions for dark matter and for the dark-energy stuff that contributes more than two-thirds of the density of the universe, bases for changes in the rate of expansion of the universe, and bases for other elementary-particle and cosmology phenomena. The mathematical basis features solutions to equations involving isotropic pairs of isotropic quantum harmonic oscillators. A subset of the solutions correlates with all known elementary particles and some of their properties. Other solutions point to possible elementary particles and some of their properties. [Preview Abstract] |
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