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T: Fachverband Teilchenphysik

T 86: Search for New Particles IV

T 86.2: Vortrag

Donnerstag, 18. März 2021, 16:15–16:30, Tk

Search for long-lived particle decays in the CMS tracker — Lisa Benato, Melanie Eich, Gregor Kasieczka, •Karla Peña, and Jörg Schindler — Institut für Experimentalphysik, Universität Hamburg

Higgs-portal models propose the existence of a dark sector, neutral under all Standard Model (SM) gauge groups. Interaction between the dark sector and the SM is mediated solely by the Higgs boson, which mixes with its dark partner. As a consequence of this, the Higgs boson is predicted to decay also in the dark sector. Scenarios are considered where the Higgs boson decays into a pair of dark long-lived particles (LLPs), each of which travels a macroscopic distance before decaying back to a pair of SM particles—predominantly b quarks.

Decays occurring within the CMS tracking system result on displaced-vertex signatures, which can be observed with almost no background from the SM. However, as conventional tracking and vertex finding algorithms are optimized for prompt decays, these signatures are challenging to find and advanced reconstruction techniques are required. Studies of machine-learning methods for displaced-vertex reconstruction will be discussed and compared to a benchmark analysis, where information from displaced tracks is used to tag jets resulting from LLP decays. The status of a search for LLPs is presented, using data collected by the CMS detector in pp collisions at √s=13 GeV.