Bulletin of the American Physical Society
2019 Annual Meeting of the APS Four Corners Section
Volume 64, Number 16
Friday–Saturday, October 11–12, 2019; Prescott, Arizona
Session D01: Plenary Talks II |
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Chair: Heinz Nakotte, New Mexico State University Room: DLC Auditorium |
Friday, October 11, 2019 1:30PM - 2:06PM |
D01.00001: Searching for Sterile Neutrinos and accelerator produced Dark Matter with the Coherent CAPTAIN-Mills Invited Speaker: Richard Van de Water The MiniBooNE and LSND experiments have shown compelling evidence for sterile neutrinos in short baseline neutrino oscillation experiments. In these experiments, an excess of electron neutrino appearance was observed from a pure muon neutrino beam, and if these data are interpreted as sterile neutrino oscillations, the mass scale is ~1 eV2. Analogous muon neutrino disappearance measurements have shown no anomalies, but these experiments have been performed at a different energy scale compared to LSND and MiniBooNE. Coherent CAPTAIN-Mills (CCM) is a new experiment to search for muon neutrino disappearance at the LSND energy scale. CCM will use a 10-ton liquid argon scintillation detector to leverage the enhanced cross section from coherent elastic neutrino-nucleus scattering. CCM will operate at the Lujan Center at LANSCE which is a 100-kW stopped pion source that delivers an 800-MeV proton beam onto a tungsten target at 20 Hz with a pulse width of 275 ns. This fast pulsing is crucial for isolating the monoenergetic muon neutrino in time and reducing neutron backgrounds. Furthermore, new vector portal dark sector models predict beam dump experiments like CCM are sensitive to sub-GeV dark matter production with sensitivities that probe early Universe relic density limits. In this talk, I will describe the current state of sterile neutrino and dark matter theories, describe the CCM detector and sensitivities, and show first results from our successful Fall 2018 commissioning run. [Preview Abstract] |
Friday, October 11, 2019 2:06PM - 2:42PM |
D01.00002: The XYZ Affair: Tales of the Third (and Fourth) Hadrons Invited Speaker: Richard Lebed In the past 16 years, dozens of new fundamental particles have been discovered that are clearly hadrons (compounds of quarks interacting via the strong nuclear force, QCD), but do not seem to fit into either of the known hadron categories of meson (quark-antiquark) or baryon (3 quarks). Many of these ``exotic'' particles, called X, Y, and Z, are now believed to be tetraquarks, and in July, 2015 the LHC announced the discovery of pentaquark states, P\textunderscore c. We begin by examining the basics of QCD, and then turn to the question of how conventional hadrons are identified, which allows one to distinguish exotics. After reviewing their experimental discovery, we consider the question of how exotics are assembled. Several competing physical pictures attempt to describe the structure of exotics: as molecules of known hadrons, as the result of kinematical effects, and others. I propose that they can arise due to the formation of compact diquarks, a well-known but under-appreciated phenomenon of QCD. The competing facts of kinematics and diquark confinement create an entirely new kind of bound state: not a molecule with well-defined orbits, but an extended object that lasts only as long as it takes for quantum mechanics to allow the separated quarks and antiquarks to ``find'' one another, and allow decays to occur. I discuss several observed effects that support this picture. [Preview Abstract] |
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