CMS-PAS-SUS-19-002

CMS-PAS-SUS-19-002
Search for supersymmetry with a compressed mass spectrum in events with a soft $\tau$ lepton, a highly energetic jet, and large missing transverse momentum in proton-proton collisions at $\sqrt{s}=$ 13 TeV
CMS Collaboration
August 2019

Abstract: The first search for supersymmetry in events with one soft tau lepton, one energetic jet from initial state radiation, and transverse momentum imbalance is presented. These event signatures are consistent with those from supersymmetric models exhibiting co-annihilation between the scalar tau lepton ( $\tilde{\tau}$ ) and the lightest neutralino ( $\tilde\chi^{0}_{1}$ ) that could generate the observed relic density of dark matter. The data correspond to an integrated luminosity of 77.2 fb $^{-1}$ of proton-proton collisions at $\sqrt{s}=$ 13 TeV collected with the CMS detector at the CERN LHC in 2016 and 2017. The results are interpreted considering a supersymmetric scenario with a small mass difference ( $\Delta m$ ) between the chargino ( $\tilde{\chi}^{\pm}_{1}$ ) or the next-to-lightest neutralino ( $\tilde{\chi}^{0}_{2}$ ), and the lightest neutralino. The mass of the $\tilde{\tau}$ is defined as the average of the $\tilde\chi^{\pm}_{1}$ / $\tilde\chi^{0}_{2}$ and $\tilde{\chi}^{0}_{1}$ masses. The data are found to be consistent with the standard model background predictions. Upper limits at 95% confidence level are set on the $\tilde{\chi}^{\pm}_{1}$ , $\tilde\chi^{0}_{2}$ , and $\tilde{\tau}$ production cross sections for $\Delta{m}(\tilde{\chi}^{\pm}_{1}, \tilde\chi^{0}_{1}) =$ 50 GeV, resulting in a lower mass limit of 290 GeV on the mass of the $\tilde\chi^{\pm}_{1}$ / $\tilde\chi^{0}_{2}$ , which is the most stringent to date.
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; These preliminary results are superseded in this paper, PRL 124 (2020) 041803. The superseded preliminary plots can be found here.

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