Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session T09: SupersymmetryRecordings Available
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Sponsoring Units: DPF Chair: Lawrence Lee, University of Tennessee, Knoxville Room: Salon 3 |
Monday, April 11, 2022 3:45PM - 3:57PM |
T09.00001: Searches for compressed SUSY with the CMS experiment Margaret R Lazarovits Supersymmetry is a theoretical extension of the Standard Model that includes a viable dark matter candidate. This appealing yet unconfirmed theory is the target of many CMS searches. More specifically, many analyses search for evidence of supersymmetry in the notoriously difficult compressed region, where the mass of the parent sparticle is close to that of the child, constraining the phase space and leading to soft decay products. The latest results from several CMS analyses searching in the compressed sector with data from the LHC Run II are presented, including analyses interpreted in terms of stop, electroweakino and slepton models. These analyses employ different techniques to search for SUSY in a variety of final states and lead to stringent limits. |
Monday, April 11, 2022 3:57PM - 4:09PM |
T09.00002: Search for B-L RPV Supersymmetry Through Stop Pair Production in Final States with 2 b-jets and 2 Leptons Using the Run 2 Data from the ATLAS Detector James G Heinlein Supersymmetry is a natural solution to many phenomena left unexplained by the Standard Model, such as the hierarchy problem that arises due to quantum corrections to the Higgs boson mass. Models which allow for R-parity violation (RPV) are favored by recent lepton flavor anomalies and can provide insight into the neutrino mixing hierarchy. The direct pair production of the stop, the supersymmetric partner to the top quark, is of particular interest due its sizable production cross section at the LHC, which allows for searches at the TeV scale. We present a search for stop pair production, with each stop decaying via an RPV coupling to a b quark and a charged lepton. This final state with two oppositely-charged leptons and two b-quark-initiated jets allows for a high reconstruction efficiency. The reconstructed mass asymmetry is used to properly pair candidate jets and leptons to form stop candidates, enabling powerful background rejection. In this talk, I will discuss the current work on the B-L RPV stop analysis using the full Run 2 dataset collected with the ATLAS detector. |
Monday, April 11, 2022 4:09PM - 4:21PM |
T09.00003: Vertexing algorithm R&D for the search of displaced vertices with jet final states in CMS Peace Kotamnives We report on a search for displaced vertices that is model-independent, and is sensitive to long-lived particles (LLPs) under a low-background environment. This search for a pair of long-lived particles in proton-proton collisions at the LHC at √s = 13 TeV, using the CMS data collected from 2015 through 2018, corresponding to a total integrated luminosity of 140 fb-1, was analyzed and targeted to long-lived particles with mean proper decay lengths between 0.1 and 100 mm. Predicted backgrounds are low, and no significant excess of events with two displaced vertices was found. In the future iterations of the search, our vertexing algorithm will better reconstruct signals by resolving cases where a single LLP is reconstructed as multiple displaced vertices, and target spurious background events where two well-separated vertices are associated to the same jet in order to extend the signal sensitivity by relaxing track and vertex quality criteria. |
Monday, April 11, 2022 4:21PM - 4:33PM |
T09.00004: Search for Higgsinos Decaying into Semi-Long-Lived Charged Particles in the ATLAS Detector with LHC Run 2 Data Sicong Lu Higgsinos with compressed mass spectra and masses near the electroweak scale are highly motivated by naturalness considerations and consistent with cosmological evidence, yet still poorly constrained by the LHC. This search will focus on the neutralino mass splitting $Δm=m_{{\widetilde{χ}}_2^0}-m_{{\widetilde{χ}}_1^0}$, in the region of 0.3~2 GeV, which has not been covered by ATLAS analyses to date. The current limit set by LEP only excludes up to $m_{{\widetilde{χ}}_1}$~95 GeV. We plan to probe higher masses by identifying the track of a soft charged pion from the slightly long-lived (with cτ~1 mm) higgsino decay. The analysis looks for the associated production of higgsino-like chargino (${\widetilde{χ}}_1^\pm$) and neutralino (${\widetilde{χ}}_2^0$) in LHC pp collision using the ATLAS Run-2 dataset. The event signature includes a high momentum jet from initial state radiation, and a displaced pion $π^\pm$ from ${\widetilde{χ}}_1^\pm/{\widetilde{χ}}_2^0$ decay aligned with significant missing energy in the transverse plane. Using Monte Carlo simulation, I will present a preliminary sensitivity estimate for $m_{{\widetilde{χ}}_1^0}$~150 GeV, and suppression strategy against backgrounds from semi-long-lived particles using track energy loss and secondary vertex reconstruction. |
Monday, April 11, 2022 4:33PM - 4:45PM |
T09.00005: Investigation of the String Landscape in the Free Fermionic Heterotic String formalism via an extended gauge framework Abinash Kar, Kameron Scott, Brian Lewis, Cooper Pich, Cooper K Watson, Gerald B Cleaver Taming the large landscape of vacua is a central problem in string phenomenology and is critical to making progress in string theory. An effort to explore this landscape of string vacua via the use of high-performance computing and a suitable construction method has been made in [1]. Here, we will focus on the Free Fermionic Heterotic String (FFHS) construction formalism presented in [1] but will extend the gauge framework presented therein in our attempt to make the model building approach more robust and encompassing. We explicitly construct all layer 1 extended gauge, FFHS models and present an overview of the model building process, redundancies therein, and methods used to deal with such redundancies. Finally, statistics for both 4d N=4 and N=0 SUSY models are presented. |
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