Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session J17: Collider and BSM II |
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Sponsoring Units: DPF Chair: Sam Higginbotham, Princeton University Room: Sheraton Grand Ballroom II |
Sunday, April 14, 2019 1:30PM - 1:42PM |
J17.00001: Studies of Z → 4ℓ decays in pp collisions at √s = 8 and 13 TeV J. Lovelace Rainbolt, Michael Schmitt Z boson decays to four leptons (electrons and muons) are studied in pp collisions at √s = 8 and 13 TeV. The data, collected with the CMS detector at the LHC, correspond to a total integrated luminosity of 19.7 fb-1 at 8 TeV and of 77.4 fb-1 at 13 TeV. The branching fraction for all four-lepton decay modes, ℬ(Z → 4ℓ), is measured. The first measurements of the branching fractions for the decays Z → 4μ, Z → 4e, and Z → 2μ2e are also presented. Differential decay rates are measured as functions of kinematic and angular quantities in the center-of-mass frame. In addition, the first tests for CP violation in Z → 4ℓ decay, in the form of triple product asymmetry measurements, are performed. The results are compared to standard model predictions and are used to set limits on new physics in the Z → 4ℓ channel. |
Sunday, April 14, 2019 1:42PM - 1:54PM |
J17.00002: Search for WWW production with data collected by the CMS Detector at √s = 13 TeV Saptaparna Bhattacharya We present a search for WWW production at √s = 13 TeV with 35.9 fb-1 of data collected by the CMS detector. The analysis is performed in the same-signed dilepton and trilepton final states. The former final state arises from the production of W±W±W, where two W bosons decay leptonically, while the third W boson decays hadronically. The latter final state results from the purely leptonic decays of the W boson. In addition, we also probe the existence of anomalous quartic gauge couplings and place limits on Wilson coefficients associated with dim-8 CP conserving operators. The existence of a photo-phobic axion-like particle, that is expected to decay into a triboson final state, is also explored. |
Sunday, April 14, 2019 1:54PM - 2:06PM |
J17.00003: Study VBS ZZ Production with the ATLAS experiment Jing Li The study of vector boson scattering (VBS) in ZZjj events produced in proton-proton collisions at 13 TeV will be reported. Data used in analysis were collected by the ATLAS experiment during Run II and correspond to a total integrated luminosity of 140 fb-1. Final states with four-charged lepton (4l) or two-charged lepton plus two neutrinos from the ZZ decays produced in association with two forward/backward jets are used to extract the VBS ZZjj signal. The inclusive VBS ZZjj production cross section will be measured. The electroweak VBS ZZ signal strength will be extracted with the BDT based analysis. |
Sunday, April 14, 2019 2:06PM - 2:18PM |
J17.00004: ABSTRACT WITHDRAWN
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Sunday, April 14, 2019 2:18PM - 2:30PM |
J17.00005: Heavy quarks within the electroweak multiplet Jaime Besprosvany, Ricardo Romero Standard-model fields and their associated electroweak Lagrangian are equivalently expressed in a shared spin basis. The scalar-vector terms are written with scalar-operator components acting on quark-doublet elements, and shown to be parametrization-invariant. Such terms, and the t- and b-quark Yukawa terms are linked by the identification of the common mass-generating Higgs operating upon the other fields, after acquiring a vacuum expectation value v. Thus, the customary vector masses are related to the fermions' fixing the t-quark mass mt with the relation mt2 +mb2=v2/2 either for maximal hierarchy, or given the b-quark mass mb, implying mt ≈173.9 GeV, for v=246 GeV. A sum rule is derived for all quark masses that generalizes this restriction. arXiv:1701.01191v2 [hep-ph] , To be published, PRD (2019). |
Sunday, April 14, 2019 2:30PM - 2:42PM |
J17.00006: Measurement of the associated production of a Higgs boson with a top quark pair in final states with electrons, muons and hadronic tau leptons in data recorded in 2017 at 13 TeV Zhengcheng Tao The production of a Higgs Boson associated with a top quark pair (ttH) is measured in the final states with electrons, muons and hadronic taus. Events are selected from proton-proton collisions with 13 TeV center-of-mass energy, recorded by the CMS experiment in 2017 corresponding to an integrated luminosity of 41.5 /fb. The analysis sensitivity is optimized by using machine learning and matrix element methods. The observed (expected) ttH production rated is 0.75+0.46-0.43 (1.00+0.39-0.35) times the expected rate in the standard model. This corresponds to an observed (expected) significance of 1.7 (2.9) sigma. These results are in addition combined with those previously obtained from the data collected in 2016, corresponding to an integrated luminosity of 35.9 /fb. The observed (expected) signal rate for the combined fit is 0.96+0.34-0.31 (1.00+0.30-0.27) times the expected rate in the standard model, which corresponds to an observed (expected) significance of 3.2 (4.0) sigma. |
Sunday, April 14, 2019 2:42PM - 2:54PM |
J17.00007: Search for H gamma resonance in boosted large-R jet plus photon final states in pp collisions at √s=13 TeV with the ATLAS detector Boping Chen Many extensions of the Standard Model predict a new particle that decays into a Standard Model Higgs boson and a photon. In 2018, a search for a heavy resonance in final states with a hadronically Z/W/H boson and a photon shows that the 2015+2016 data are consistent with the Standard Model expectation. This talk presents an updated search with an integrated luminosity of 140 fb-1 (from 2015 to 2018) collected by the ATLAS detector at the Large Hadron Collider to search for such resonances produced in pp collisions at √s=13 TeV. In the analysis, boosted hadronically decaying Higgs bosons are reconstructed as single jets and identified through their decays to b-hadrons by a new tagging technique: center of mass (CoM) algorithm. In this talk, we will describe the analysis strategy, the new CoM algorithm and its expected improvement of experimental sensitivity comparing to previous searches. |
Sunday, April 14, 2019 2:54PM - 3:06PM |
J17.00008: Experimental search for coherent radar reflections from an electron-beam induced particle cascade Steven Prohira, Krijn de Vries, Dave Besson, Amy L Connolly, Uzair Latif, Thomas Meures, John Ralston, Zoe Riesen, David P Saltzberg, Jorge Torres, Stephanie Ann Wissel, Xinzhe Zuo, Jiwoo Nam, Alisa Nozdrina, James Justin Beatty In development of a new detection scheme for the highest energy neutrinos, experiment T576 at SLAC was designed to detect a radar reflection from a high-energy particle cascade. High energy particles incident on dense materials (ice, salt, sand, etc.) will produce a cascade of secondary particles which pass relativistically through the material. As they do so, they kick out electrons from the material, forming a short-lived plasma. For high enough incident particle energies, this ionization density will be high enough to reflect incident radio frequency fields, and thereby allow for remote detection. The electron beam at SLAC, containing approximately N=109 electrons at 109 eV was used as a proxy for a single high energy neutrino of 1018 eV, and directed into a plastic target to produce a cascade. This cascade was interrogated with RF of various frequencies and amplitudes, and measured with a variety of receiving antennas. This talk will detail the discovery potential of - and challenges inherent to - the detection technique, outline the experimental goals of T576, discuss the measurements taken during two separate runs in 2018, and present preliminary results from the analysis. |
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