Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session C17: Collider and BSM I |
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Sponsoring Units: DPF Chair: Tae Min Hong, University of Pittsburgh Room: Sheraton Grand Ballroom II |
Saturday, April 13, 2019 1:30PM - 1:42PM |
C17.00001: Electroweak and QCD aspects in V+jets Daniel J Arcaro Z boson production in association with jets at the LHC is a major source of background to standard model searches and it provides sensitive evaluation of the precision of perturbative QCD predictions. Total and differential cross-section measurements of the Z boson produced in association with jets in proton-proton collisions at the LHC are presented as a function of the jet transverse momentum, rapidity, and multiplicity. The measurements are compared to next-to leading order QCD calculations and event simulations that utilize matrix element calculations interfaced with parton showers. |
Saturday, April 13, 2019 1:42PM - 1:54PM |
C17.00002: New CTEQ global analysis of quantum chromodynamics with high precision data from the LHC Keping Xie We present the new CTEQ-TEA global analysis of quantum chromodynamics (QCD). In this analysis parton distribution functions (PDFs) of the nucleon are determined within the Hessian method at the next-to-next-to-leading order (NNLO) in perturbative QCD, based on the most recent measurements from the Large Hadron Collider (LHC) and a variety of world experimental collider data. Next-to-leading order (NLO) and leading order (LO) PDFs are also determined. Because of difficulties in fitting both the ATLAS 7 and 8 TeV W and Z vector boson production cross section data, we present two families of PDFs, named CT18 and CT18Z PDFs respectively, without and with the ATLAS 7 TeV W and Z measurements. We study the impact of the CT18 family of PDFs on the theoretical predictions of standard candle cross sections at the LHC and the role of PDF uncertainties. |
Saturday, April 13, 2019 1:54PM - 2:06PM |
C17.00003: Toward Mueller-Tang Jets at Next-to-Leading Order Federico Deganutti, Christophe Royon, Timothy Raben
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Saturday, April 13, 2019 2:06PM - 2:18PM |
C17.00004: Search for Single Production of Vector-like Quarks (Top Partners) in the Multilepton Channel at the ATLAS Experiment at the LHC Avik Roy, Timothy R Andeen This talk summarizes a search for a heavy, up-type vector-like quark (VLQ), or Top-partner, with charge +⅔. Top-partners are predicted in many well-motivated models of new physics beyond the Standard Model. The analysis uses 36.1/fb of pp collisions with a center of mass energy of 13 TeV at the LHC and recorded by the ATLAS detector to search for Top-partners resulting form the fusion of a W boson and a bottom quark and decaying into a Z boson and a top quark, resulting in a final state signature of two or three leptons. These leptons consist of a pair of opposite sign same flavor leptons from the decay of the Z boson as well as either a third lepton from the decay of the W boson, in association with a neutrino, or a hadronically decaying top quark. Since no evidence is found for a signal, upper limits have been placed on the production cross-section of VLQs. This talk will also present a generalized algebraic framework for interpreting the results of a generic search for the single production of VLQs in terms of the free parameters in the VLQ Lagrangian. It explains how this framework can be utilized to formulate a strategy for combination of multiple single VLQ searches. |
Saturday, April 13, 2019 2:18PM - 2:30PM |
C17.00005: Search for vector-like quarks in events with two oppositely charged leptons and jets in proton-proton collisions at √s = 13 TeV Dalath Rachitha A Mendis A search for the pair production of vector-like T and B quarks is presented by using proton-proton collision data collected at center-of-mass energy √s = 13 TeV by the CMS experiment in 2016 that corresponds to an integrated luminosity of 35.9 fb-1. For TTbar production, one of the T quark decays via T→ tZ and other via T→ tZ, tH or bW. For BBbar production, one of the B quark decays via B→ bZ and other via B → bZ, bH or tW . Final state consists of two opposite sign leptons (muons or electrons) consistent with coming from the decay of a Z boson and jets. Lower limits at 95% confidence level are placed on the masses of the T and B quarks for a range of branching fractions. Assuming 100% branching fractions for T → tZ, and B → bZ, T and B quark mass values below 1280 and 1130 GeV are excluded at 95% CL respectively. |
Saturday, April 13, 2019 2:30PM - 2:42PM |
C17.00006: Search for vector-like quarks decaying to an all-jets final state using pp collisions at √s = 13 TeV Reyer Band We present a search for the pair production of vector-like, charge 2/3e quarks “T”, in the all-hadronic final state. Proton-proton collisions at a sqrt(s) = 13 TeV are analyzed using 35.9 fb−1 of data collected by the CMS detector at the Large Hadron Collider during 2016 collisions. We utilize boosted substructure techniques, including N-subjettiness and soft drop mass to identify vector boson hadronic decays. This search optimizes sensitivity to the T->bW decay, but provides interpretations and limits for all possible decays of the T. The results of this cut-based search are complementary to results of a search utilizing the BEST neural-net tagger. |
Saturday, April 13, 2019 2:42PM - 2:54PM |
C17.00007: Search for W’ boson in top-quark final states in pp collisions at √s = 13 TeV with the ATLAS detector Kuan-Yu Lin A search for W’ production with decay to a top quark and a bottom quark in proton-proton collisions at √s = 13 TeV with the ATLAS detector is presented. The hadronic decay of the top quark is identified using boosted-object techniques. This talk will describe the background estimation and improvements to the signal sensitivity compared to previous analyses. |
Saturday, April 13, 2019 2:54PM - 3:06PM |
C17.00008: Search for low mass Z' signature in four muon final state with the ATLAS detector. Shuzhou Zhang A search for a low mass Z' particle in final states with four muons will be reported. This search is motivated by a recently observed discrepancy by the LHCb Collaboration in the rare decay of B meson to electrons and muons. A new physics model intending to describe the observed anomaly introduces a new neutral vector boson, Z', that only couples to muons and taus. We conducted a search through the 'radioactive' Z-->mu mu decays, where one muon radiates a Z' boson, which then decays to a pair of muons ($\mu^+ \mu^-$). This search uses the full data-set collected by the ATLAS detector in Run 2 with a total luminosity of 140 fb^-1 and is sensitive to Z' bosons in the mass range 5 to 70 GeV. |
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