Heidelberg 2022 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 37: Search for New Particles 2

T 37.8: Vortrag

Dienstag, 22. März 2022, 18:00–18:15, T-H22

Search for long-lived particles within the CMS tracker — Karim El Morabit, Lisa Benato, Melanie Eich, Gregor Kasieczka, and •Karla Pena — Institut für Experimentalphysik, Universität Hamburg

Several theories for physics beyond the standard model (BSM) predict the existence of long-lived particles (LLPs) that have comparably long lifetimes leading to macroscopic flight distances. Higgs-portal models, for example, propose the existence of a dark sector with particles that are neutral under the standard model (SM) gauge groups. In such theories, the SM Higgs boson mixes with a dark partner and acts as a mediator between the SM and the dark sector. The SM Higgs boson could then decay to a pair of dark sector LLPs which subsequently decay to SM particles – predominantly into bottom quark-antiquark (bb ) pairs.

This talk discusses searches for LLPs using data recorded with the CMS experiment at a center-of-mass energy of 13 TeV. The searches target events in which the LLPs decay into bb pairs within the CMS tracking system after flight distances ranging from micrometers up to 1 m. The signature of the signal events consists of bb originating from displaced vertices. The searches face different challenges depending on the lifetime of the LLPs. For short lifetimes, the decay products of LLPs need to be distinguished from those of SM particles, while the search for longer lifetimes requires dedicated tracking and vertex reconstruction methods. In both cases the challenges are tackled using machine learning approaches.