CMS-PAS-EXO-20-015

CMS-PAS-EXO-20-015
Search for long-lived particles decaying in the CMS endcap muon system in proton-proton collisions at $\sqrt{s}=$ 13 TeV
CMS Collaboration
May 2021

Abstract: A search for long-lived particles (LLPs) produced in decays of standard model (SM) Higgs bosons in 137 fb $^{-1}$ of proton-proton collisions at $\sqrt{s}=$ 13 TeV recorded by the CMS experiment during 2016-2018 is presented. The search employs a novel technique to reconstruct hadronic decays of LLPs in the endcap muon system. The search is sensitive to a broad range of LLP decay modes including $\tau^{-}\tau^{+}$ , LLP masses as low as a few GeV, and is largely model-independent. No excess of events above the SM background is observed and stringent limits on the Higgs boson ( $\mathrm{h}^0$ ) branching fraction to LLPs ( $\mathrm{S}$ ) are obtained, particularly for proper decay lengths greater than a few meters. This search result represents the most stringent limits on the branching fraction $\mathcal{B}(\mathrm{h}^0 \rightarrow\mathrm{S}\mathrm{S})$ for proper decay lengths greater than 6-40 m for S masses between 7-40 GeV.
Links: CDS record (PDF) ; inSPIRE record ; Physics Briefing ; CADI line (restricted) ; These preliminary results are superseded in this paper, PRL 127 (2021) 261804. The superseded preliminary plots can be found here.

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