CMS-PAS-EXO-19-016

CMS-PAS-EXO-19-016
Search for a third-generation leptoquark coupling to a $\tau$ lepton and a b quark through single, pair and nonresonant production at $\sqrt{s}= $ 13 TeV
CMS Collaboration
July 2022

Abstract: A search is presented for a third-generation leptoquark (LQ) coupling to a $\tau$ lepton and a b quark. Events with $\tau$ leptons plus at least one jet originating from a b quark are considered, targeting the single and pair production of the LQ as well as nonresonant production via $t$-channel LQ exchange. The search is based on proton-proton collision data at a center-of-mass energy of $\sqrt{s}= $ 13 TeV recorded with the CMS detector, corresponding to an integrated luminosity of 137 fb$^{-1}$. Upper limits are set on the LQ production cross section in the LQ mass range 0.5-2.3 TeV. Lower limits at 95% confidence level on the LQ mass are set in the 1.22-1.96 TeV range and for a coupling strength less than 2.5, depending on the LQ model. Upper limits are also set on the coupling strength of such LQs as a function of their mass. For a representative LQ mass of 2 TeV and a coupling strength of 2.5, an excess with a significance of 3.4 standard deviations above the standard model expectation is observed in the data. Consequently, the observed upper limits on the LQ production cross section are about three times larger than expected for this benchmark.
Links: CDS record (PDF) ; CADI line (restricted) ; These preliminary results are superseded in this paper, Submitted to JHEP. The superseded preliminary plots can be found here.

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