Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session X15: Collider and BSM V |
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Sponsoring Units: DPF Chair: Kate Whalen, CERN Room: Sheraton Plaza Court 4 |
Tuesday, April 16, 2019 10:45AM - 10:57AM |
X15.00001: Direct Detection limits on milli-charged particles from the DAMIC-100 Experiment at SNOLAB Karthik Ramanathan The DAMIC (Dark Matter in CCDs) experiment utilizes high resistivity, scientific grade CCDs to search for ionization interactions produced by Dark Matter. However with a demonstrated combination of low electronic noise of 1.6 e−, an ionization response threshold of 35 eVee and high spatial resolution of particle interactions, the experiment is also suited for searches of exotic physics. One such candidate, milli-charged particles (mCPs), are fractionally charged particles that interact purely electromagnetically and are motivated by certain extensions to the Standard Model. By combining a search for spatial coincidences with constraints from leakage current, we present here the results of a ~7 kg-day search for mCPs with the current iteration of the experiment, DAMIC-100 at SNOLAB, and place stringent direct detection limits on the mCP flux from fractional charge e/6 to e/10000. |
Tuesday, April 16, 2019 10:57AM - 11:09AM |
X15.00002: The Search for Lightly Ionizing Particles Using the 90-day Run Data of the Large Underground Xenon Experiment Paul A Terman The question of the nature of dark matter has become increasingly puzzling as more experiments exclude larger portions of the favored WIMP parameter space. Previous theoretical work has suggested the existence of Lightly Ionizing Particles (LIPs) with charge e·f, where e is the electron charge and f < 1. At least a part of the dark matter could consist of these LIPs. We seek to utilize data from the 90-day WIMP search of the Large Underground Xenon (LUX) experiment to search for LIPs in the charge range f = 0.01 to 0.25. To accomplish the aforementioned search new methods of Geant4 based simulation and data processing have been implemented. |
Tuesday, April 16, 2019 11:09AM - 11:21AM |
X15.00003: Search for VBF Bulk Graviton decaying to Z(nunu)Z(qqbar) final state Kamal Lamichhane Beyond the standard model theories like Extra-Dimensions predict heavy resonances corresponding to a graviton (a spin 2 particle) and can explain the gauge hierarchy problem. At LHC these gravitons can be produced through quark/anti-quark annihilation, gluon fusion, or vector boson fusion (VBF) processes. In scenarios where the coupling between the graviton and both light quarks and massless vector bosons are suppressed, production and decay via weak vector bosons are a critical probe of the existence of extra dimensions. We present the search for Bulk Graviton in VBF production mode, decaying to a pair of Z bosons where one Z decays to a pair of neutrinos, and the other decays to a merged jet due to the large momentum imparted to the Z bosons through the decay process of high mass gravitons. Tagging techniques for both forward jets produced in the VBF process and for identifying quarks from Z decays which fragment into a merged jet will be discussed. Challenges to traditional semi-visible resonance search techniques, which arise from a confluence of polarization effects and a partially reconstructed final state, will be presented. Finally, expected results of interpretations in the context of a Randall-Sundrum Warped Extra Dimensions model using LHC Run-2 datasets will be given. |
Tuesday, April 16, 2019 11:21AM - 11:33AM |
X15.00004: Search for LPV decay $Z\to e \mu$ in $pp$ collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector Fenfen An, Hai Jiang, Chunhui Chen, Soeren Andre Prell, Jim Cochran The ATLAS detector at the Large Hadron Collider is used to search for the lepton flavor violating process $Z \to e\mu$ in $pp$ collisions with 140 fb$^{−1}$ of data collected at $\sqrt{s}$ = 13 TeV. This analysis looks for an enhancement in the eμ invariant mass spectrum at the $Z$ boson mass. The number of $Z$ bosons produced in the data sample is estimated using events of similar topology, $Z \to ee$ and $\mu\mu$, thus reducing the majority of uncertainties in tracking, isolation and particle identification. The detailed methodology is given in the talk. The preliminary result shows an improved sensitivity in addition to the statistical gain compared to the Run I analysis. |
Tuesday, April 16, 2019 11:33AM - 11:45AM |
X15.00005: Probing leptoquark chirality via top polarization at the colliders Joydeep Roy Anomalies in recent LHCb, Belle and Babar measurements of , and , in B decays may indicate the new physics beyond the Standard Model (SM). The leptoquarks (LQ) that couple to the generation quarks and leptons have been proposed as a viable new physics (NP) explanation. Such left-handed LQs can couple to both bottom and top quarks. Since top particles decay before the hadronization, it is possible to reconstruct chirality of boosted top quarks and consequently the chirality of top coupling to the LQs. We perform analysis on the top quark's chirality in the pair-production channel of the LQ, which can be purely left-handed in comparison to unpolarized tt¯ SM background. We study the prospects of distinguishing the chirality of a potential LQ signal for the high luminosity run of the LHC and other future colliders.
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Tuesday, April 16, 2019 11:45AM - 11:57AM |
X15.00006: The REDTOP experiment: Rare Eta Decays with a TPC for Optical Photons Erik J Ramberg, Roger Rusack The $\eta$ and $\eta'$ mesons are almost unique in the particle universe since they are |
Tuesday, April 16, 2019 11:57AM - 12:09PM |
X15.00007: New constraints on exotic spin- and velocity-dependent interactions of polarized electrons with an atomic magnetometer Young Jin Kim, Pinghan Chu, Igor M Savukov, Shaun Newman Many theoretical extensions of the Standard Model of particle physics predicted exotic spin-dependent interactions between fermions mediated by new fundamental spin-0 or spin-1 bosons such as the axion and axionlike particles. The new bosonic particles may explain several important unsolved mysteries in physics, e.g., matter-antimatter asymmetry and the existence of the dark matter. Recently, we conducted a search for exotic spin- and velocity-dependent interactions for polarized electrons. The experiment is based on a high-sensitivity atomic magnetometer containing an optically polarized atomic vapor, which serves as both a source of polarized electrons and a magnetic-field detector. This approach aims to detect magnetic-fieldlike effects from the exotic interactions between the polarized electrons in an atomic magnetometer vapor cell and unpolarized nucleons of a closely located solid-state mass. In this talk, we report new experimental constraints on the exotic interactions. |
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