Bulletin of the American Physical Society
87th annual meeting of the Southeastern Section of the APS
Volume 65, Number 19
Thursday–Friday, November 5–6, 2020; Virtual
Session B05: Particle Physics |
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Chair: Tova Holmes, University of TN |
Thursday, November 5, 2020 11:00AM - 11:12AM |
B05.00001: Rare Higgs Decays into $Z$ $J/\psi$ Himal Acharya Rare decays of Higgs bosons into the $Z$-boson together with a vector meson are a promising laboratory to search for physics beyond the standard model (BSM). Such BSM physics might alter Yukawa couplings to lighter quarks and add loop diagrams, possibly resulting in higher decay rates than predicted by the standard model. A search for decays of the Higgs boson into a $Z$-boson and a $J/\psi$ meson, with subsequent decays of the $J/ \psi$ meson into muon pairs, and the $Z$-boson into an electron or muon pair is performed with the Compact Muon Solenoid detector at the Large Hadron Collider (LHC). A data sample of proton-proton collisions collected at a center-of-mass energy of 13 TeV during the LHC Run-2 is used. I will present the searches and implications for future searches of BSM signatures at high luminosity. [Preview Abstract] |
Thursday, November 5, 2020 11:12AM - 11:24AM |
B05.00002: Precision Timing with the CMS MTD Barrel Timing Layer for HL-LHC Matthew Joyce The Compact Muon Solenoid (CMS) detector at the CERN Large Hadron Collider (LHC) is undergoing an extensive Phase II upgrade program to prepare for the challenging conditions of the High-Luminosity LHC (HL-LHC). In particular, a new timing layer will measure minimum ionizing particles (MIPs) with a time resolution of \textasciitilde 30ps and hermetic coverage up to a pseudo-rapidity of \textbar $\eta $\textbar $=$3. This MIP Timing Detector (MTD) will consist of a central barrel region based on LYSO:Ce crystals read out with SiPMs and two end-caps instrumented with radiation-tolerant Low Gain Avalanche Diodes. The precision time information from the MTD will reduce the effects of the high levels of pile-up expected at the HL-LHC and will bring new and unique capabilities to the CMS detector. The time information assigned to each track will enable the use of 4D reconstruction algorithms and will further discriminate interaction vertices within the same bunch crossing to recover the track purity of vertices in current LHC conditions. We present motivations for precision timing at the HL-LHC and the ongoing MTD R{\&}D targeting enhanced timing performance and radiation tolerance for the barrel layer components. [Preview Abstract] |
Thursday, November 5, 2020 11:24AM - 11:36AM |
B05.00003: Single-Photon Low-Energy Excess Search at MicroBooNE Wei Tang MicroBooNE is a 85-ton active volume Liquid Argon Time Projection Chamber (LArTPC) which has been collecting data from the Booster Neutrino Beam at Fermilab since 2015. LArTPCs are imaging detectors that present neutrino interactions with excellent spatial resolution and is the technology choice for next generation of neutrino experiments. One of the main goals of MicroBooNE is to investigate the low energy excess (LEE) of electromagnetic-like events observed by the MiniBooNE experiment. One interpretation of the MiniBooNE LEE is that it could be due to photons from neutral current $\Delta$ (1232) decays ($\Delta$(1232) $\to$ N$\gamma$) mis-identified as electrons. In this talk, I will give an overview of the analysis and present recent results from MicroBooNE’s single-photon LEE Search. [Preview Abstract] |
Thursday, November 5, 2020 11:36AM - 11:48AM |
B05.00004: Systematic Studies for a Photon-like Low Energy Excess Search at MicroBooNE Gray Yarbrough MicrBooNE is part of the global neutrino physics program which is currently focused on studying neutrino oscillations seeking explanation to questions such as the matter-antimatter asymmetry. The ``low energy excess'' (LEE) of electron neutrino and antineutrino charged current quasi-elastic events observed in the MiniBooNE experiment is a result that has great theoretical implications, but these depend on confirmation of the identification of these events. The MicroBooNE liquid argon time projection chamber (LArTPC) detector at Fermilab was built primarily to investigate this LEE. One possible interpretations of the MiniBooNE LEE is that it is comprised of neutrino-induced single-photon events. MicroBooNE is testing this hypothesis via a study of neutral current resonant delta production with subsequent radiative decay. This talk will cover the related studies to fully understand the systematic uncertainties of this single photon analysis, including re-weighting Monte Carlo events to estimate the effect of many flux and cross-section uncertainties as well as detector systematics. In addition, a simulation of constraining the final uncertainties utilizing secondary signal studies including neutral current pion production and subsequent decay is presented. [Preview Abstract] |
Thursday, November 5, 2020 11:48AM - 12:00PM |
B05.00005: Constraining the Neutral Current $\pi^0$ Background for MicroBooNE's Single-Photon Search Andrew Mogan Liquid Argon Time Projection Chambers (LArTPCs) are an important technology in the field of experimental neutrino physics due to their exceptional calorimetric and position resolution capabilities. In particular, their ability to distinguish electrons from photons is crucial for current and future neutrino oscillation experiments. The MicroBooNE experiment is utilizing LArTPC technology to investigate the MiniBooNE low-energy excess, which could be either electron-like or photon-like in nature. To test the photon-like hypothesis, MicroBooNE is searching for single-photon events, a likely source of which is the neutral current (NC) $\Delta$ radiative decays. However, this search is complicated by the significantly more common neutrino-induced NC resonant $\pi^0$ production process. This talk presents the method for constraining this NC $\pi^0$ background for the single photon analysis by selecting two-photon events which are characteristic of the NC $\pi^0$ topology. The selected sample is then used to constrain the systematic uncertainty on the NC $\Delta$ radiative decay measurement. [Preview Abstract] |
Thursday, November 5, 2020 12:00PM - 12:12PM |
B05.00006: Charged current pion-less interactions with final state protons at MicroBooNE Libo Jiang, Andy Furmanski, Mike Kirby, Steve Dytman MicroBooNE is an 85t active volume liquid argon time projection chamber (LArTPC) in the Booster Neutrino Beam (BNB) at Fermilab. The BNB is a wide band beam, with an energy spectrum distributed primarily between 200 MeV and 1.5 GeV. Due to the high granularity calorimetry available in a LArTPC, the low energy protons produced in neutrino interactions can be measured with high statistics down to lower thresholds. The higher A of the target makes kinematic reconstruction more complicated and more model dependent. Therefore, nuclear effects can be significant in argon experiment. This talk will present a measurement of the CC0piNp channel, that is interactions which do not produce a final state pion but do produce one or more final state protons above a momentum threshold of 300 MeV/c. We use a MicroBooNE data sample corresponding to an exposure of 1.6 x 10^20 protons-on-target (POT), to measure single differential cross sections in five variables, each sensitive to different effects. These variables are compared to predictions from multiple state-of-the art neutrino interaction generators. [Preview Abstract] |
Thursday, November 5, 2020 12:12PM - 12:24PM |
B05.00007: Search for Direct Production of Dark Leptophilic Scalar Romulus Godang Physics beyond the Standard Model predicts the existence of new gauge singlets which is lighter than the weak scale. The new scalars with masses in the MeV to Gev range could be weakend if the scalars interact predominantly with leptons. Based on a data sample of 540/fb at the Upsilon(2S), Upsilon(3S), and Upsilon(4S) resonances collected by the BABAR Experiment at SLAC, we report a new dark leptophilic scalar produced mainly via final-state radiation from tau leptons at e$+$e- collider. The limits significantly improve upon the previous constraints over a large range of masses below dimuon threshold. [Preview Abstract] |
Thursday, November 5, 2020 12:24PM - 12:36PM |
B05.00008: The 't Hooft Model interpolating between the Instant Form Dynamics and the Light-Front Dynamics Bailing Ma, Chueng-Ryong Ji The $1+1$ dimensional Quantum Chromodynamics with the large $N_c$ limit, known as the 't Hooft model, plays an important theoretical role for the study of strong interactions exhibiting confinement and mass gap. The 't Hooft model was originally formulated and solved utilizing the boost invariance of the Light-Front Dynamics (LFD). Since then, it was formulated also in the Instant Form Dynamics (IFD) and solved in specific reference frames such as the target rest frame and the infinite momentum frame. In this work, we reformulate it in the quantization form interpolating between the LFD and the IFD. Introducing an interpolation angle parameter, $\delta$, we connect and combine the familiarity of the ordinary time evolution in the IFD with the distinguished features including the vacuum structure in the LFD. The mass spectra of the mesons turn out to be independent of the $\delta$ value as expected. Meson wavefunctions and parton distribution functions (PDFs) are analyzed with the interpolation angle parameter $\delta$ in this generalized quantization form. The effects of boosting frames are studied in different forms of dynamics and the quasi-PDFs in IFD are contrasted with the PDFs in LFD. [Preview Abstract] |
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