Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session S18: Electroweak and Standard Model Physics ILive
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Sponsoring Units: DPF Chair: Seego Jindariani, Fermilab |
Monday, April 19, 2021 1:30PM - 1:42PM Live |
S18.00001: Search for physics beyond the standard model in final states involving a leptonically decaying Z boson, jets and missing transverse momentum with the CMS detector Balaji Venkat Sathia Narayanan A search for phenomena beyond the standard model (BSM) is presented with final states containing an on-shell Z boson decaying to two opposite sign same flavor leptons, jets, and missing transverse momentum. The search uses a data sample of proton-proton collisions at $\sqrt{s} = 13$ TeV collected over a period of three years (2016-18) with the CMS detector corresponding to an integrated luminosity of 137 fb$^{-1}$. A potential BSM signature that manifests as an excess of events with a lepton pair whose invariant mass is consistent with the Z boson mass is explored. The observed event yields are consistent with backgrounds expected from the standard model. The results are used to constrain BSM physics models involving pair production of gluinos, or charginos and neutralinos. [Preview Abstract] |
Monday, April 19, 2021 1:42PM - 1:54PM Live |
S18.00002: Search for new physics in the monophoton final state using full run II data De-Lin Macive Xiong Events with a final state composed of a single high energy photon and a large missing transverse momentum can be sensitive probes of new physics at the LHC. The monophoton final state has the advantage of being identified with high efficiency and high purity. The preliminary result of a search for new physics using the full run II dataset by the CMS with an integrated luminosity of 137 fb\textasciicircum -1 \begin{figure}[htbp] \centerline{\includegraphics[width=0.24in,height=0.22in]{211220201.eps}} \label{fig1} \end{figure} at a center of mass energy of 13 TeV will be presented. [Preview Abstract] |
Monday, April 19, 2021 1:54PM - 2:06PM Live |
S18.00003: A Search for new physics in the diphoton plus missing transverse momentum final state. Pampa Ghose Using the partial Run II data collected by the CMS experiment, a search for strongly produced supersymmetric particles with two high pT photons and missing transverse momentum is executed. Limits are set on SUSY particle masses in the context of simplified models. Prospects for a future analysis on the full Run II dataset exploiting novel techniques will be presented. [Preview Abstract] |
Monday, April 19, 2021 2:06PM - 2:18PM Live |
S18.00004: Search for non-pointing and delayed photons with ATLAS detector in pp collisions at $\sqrt{s}=$ 13 TeV Sai Neha Santpur, Marjorie Shapiro, Haichen Wang A search for exotic decays of the Higgs boson to long-lived supersymmetric particles is presented. In the model considered, the long-lived particles would decay to photons and the lightest supersymmetric particles that escape detection. The signature of this process involves the presence of delayed and non-pointing photons (direction of flight does not point back to the primary vertex) as well as missing transverse energy. This analysis utilizes the unique capability of the ATLAS electromagnetic calorimeter to measure photon’s direction of flight and their time of arrival very precisely. The results of the analysis are based on 139 fb$^{-1}$ of $pp$ collision data at $\sqrt s$=13 TeV using the ATLAS detector. [Preview Abstract] |
Monday, April 19, 2021 2:18PM - 2:30PM Live |
S18.00005: Search for New Physics in Channels with Two Higgs Bosons Decaying to b Quarks and Missing Transverse Momentum in Proton-Proton Collisions at 13 TeV Michael Oshiro Results are presented from a search for new physics beyond the standard model in proton-proton collisions in final states containing two Higgs bosons, each decaying via H→bb, and large missing transverse momentum. The search uses a data sample accumulated by the CMS experiment at the LHC in 2016–2018, corresponding to an integrated luminosity of 137 fb$^{-1}$. Two complementary methods are used, providing coverage of different regions of phase space according to whether the two b jets from a Higgs-boson decay are resolved into separate, small-radius jets or instead overlap into a single, large-radius jet. Results are presented and interpreted using simplified models of supersymmetry involving the direct production of electroweak SUSY partners or alternatively the strong production of gluino pairs decaying to a pair of Higgs bosons via cascade processes. [Preview Abstract] |
Monday, April 19, 2021 2:30PM - 2:42PM Live |
S18.00006: Measurement of the ttbar spin correlations, top quark polarization and related angular variables Abraham Mathew Koshy, Jason Thiemann, Giulia Negro, Andreas Jung The ongoing CMS analysis on the measurement of the full spin density production matrix, which includes multi-differential measurements of variables sensitive to the top quark spin correlation, polarization, and related angular observables, is presented. Events containing two leptons, two b-jets, and additional jets, as well as missing transverse momentum produced in proton-proton collisions at a center-of-mass energy of 13 TeV are considered. The data corresponds to an integrated luminosity of 137/fb collected with the CMS detector at the LHC. Results are used to challenge Standard Model predictions and also to indirectly search for contributions of new physics. [Preview Abstract] |
Monday, April 19, 2021 2:42PM - 2:54PM Live |
S18.00007: Searching for a Pair-Produced Supersymmetric Top Partner using Recursive Jigsaw Variables and Boosted Decision Trees in $pp$ Collisions at $\sqrt{s}=$ 13 TeV with the ATLAS Detector Jared Little Recent results will be presented of a search for the direct pair production of top squarks in events with two opposite-charge electrons or muons and missing transverse momentum. This search was performed using proton–proton collision data collected by the ATLAS detector at the Large Hadron Collider between 2015-2018. This analysis is sensitive across a wide range of mass differences between the top squark and the lightest neutralino, including the three-body decay region as well as the two-body decay region where the difference between the stop and neutralino mass approaches the mass of the top quark. For separating the signal from the background the recursive jigsaw reconstruction technique is used. It is a method that estimates the rest masses of the intermediate particles in order to construct powerful discriminating variables. We also explore a supervised learning technique, training boosted decision trees using our jigsaw variables to further push our sensitivity for discovery. [Preview Abstract] |
Monday, April 19, 2021 2:54PM - 3:06PM Live |
S18.00008: Search for Higgsinos in $\sqrt{s}=$ 13 TeV $pp$ Collisions with the ATLAS Detector Michael Hank Many supersymmetry models of general gauge mediation or gauge-mediated supersymmetry breaking predict gravitinos as the lightest supersymmetric particle and higgsino-dominated neutralinos as the next-to-lightest supersymmetric particle. This talk presents a search for higgsinos decaying to a Higgs boson and gravitino in the $b\bar{b}$ Higgs boson decay channel in $pp$ collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector. The search uses the full Run 2 dataset of the ATLAS detector with an integrated luminosity of 132.6 fb$^{−1}$, extending prior ATLAS results with 24.3 fb$^{−1}$. The search is optimized for higgsinos with mass less than 300 GeV and will be combined with an analysis targeting higgsinos with mass greater than 300 GeV. The backgrounds are dominated by difficult-to-model QCD multijet events and are estimated using a novel data-driven approach utilizing a reweighting boosted decision tree. Analysis optimizations and higher statistics yield significantly improved limits. [Preview Abstract] |
Monday, April 19, 2021 3:06PM - 3:18PM Live |
S18.00009: Search for electroweak production of charginos and neutralinos in hadronic WH, WZ, and WW final states with large missing transverse momentum. Ankush Reddy Kanuganti Results are presented from a search for the direct electroweak production of charginos and neutralinos in hadronically-decaying WH, WZ, and WW final states with a large missing transverse momentum. The results are based on a sample of proton-proton collision data collected at sqrt(s)$=$13 TeV, recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb-1. The search utilizes novel algorithms which identify hadronically decaying W, Z, and Higgs bosons, which are expected in the targeted signal models. [Preview Abstract] |
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