CERN Accelerating science

Article
Report number	arXiv:2312.09794 ; CERN-TH-2023-241
Title	Rise and Fall of Light Top Squarks in the LHC Top-Quark Sample
Related title	The rise and fall of light stops in the LHC top quark sample
Author(s)	Bagnaschi, Emanuele (CERN ; Frascati) ; Corcella, Gennaro (Frascati) ; Franceschini, Roberto (INFN, Rome3 ; Rome III U.) ; Sengupta, Dibyashree (Frascati)
Publication	2024-08-08
Imprint	2023-12-15
Number of pages	7
In:	Phys. Rev. Lett. 133 (2024) 061801
DOI	10.1103/PhysRevLett.133.061801 (publication)
Subject category	hep-ex ; Particle Physics - Experiment ; hep-ph ; Particle Physics - Phenomenology
Accelerator/Facility, Experiment	CERN LHC
Abstract	We discuss the possibility that light new physics in the top quark sample at the LHC can be found by investigating with greater care well known kinematic distributions, such as the invariant mass $m_{b\ell}$ of the $b$-jet and the charged lepton in fully leptonic $t\bar{t}$ events. We demonstrate that new physics can be probed in the rising part of the already measured $m_{b\ell}$ distribution. To this end we analyze a concrete supersymmetric scenario with light right-handed stop quark, chargino and neutralino. The corresponding spectra are characterized by small mass differences, which make them not yet excluded by current LHC searches and give rise to a specific end-point in the shape of the $m_{b\ell}$ distribution. We argue that this sharp feature is general for models of light new physics that have so far escaped the LHC searches and can offer a precious handle for the implementation of robust searches that exploit, rather than suffer from, soft bottom quarks and leptons. Recasting public data on searches for new physics, we identify candidate models that are not yet excluded. For these models we study the $m_{b\ell}$ distribution and derive the expected signal yields, finding that there is untapped potential for discovery of new physics using the $m_{b\ell}$ distribution.
Copyright/License	preprint: (License: CC BY 4.0) publication: © 2024-2025 authors (License: CC BY 4.0), sponsored by SCOAP³

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