Search for a low-mass $\tau^+\tau^-$ resonance in association with a bottom quark in proton-proton collisions at $\sqrt{s}=$ 13 TeV
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Abstract (data abstract)
A general search is presented for a low-mass $\tau^+\tau^-$ resonance produced in association with a bottom quark. The search is based on proton-proton collision data at a center-of-mass energy of $13~\mathrm{TeV}$ collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of $35.9~\mathrm{fb}^{-1}$. The observed data are consistent with the standard model expectation. Upper limits at $95\%$ confidence level on the cross section times branching fraction are determined for two hypothetical signal models: a light pseudoscalar Higgs boson decaying to a pair of $\tau$ leptons produced in association with bottom quarks, and a low-mass boson X decaying to a $\tau$ lepton pair that is produced in the decay of a bottom-like quark B such that $\mathrm{B}\to \mathrm{bX}$. Masses between $25$ and $70~\mathrm{GeV}$ are probed for the light pseudoscalar boson with upper limits ranging from $250$ to $44~\mathrm{pb}$. Upper limits from $20$ to $0.3~\mathrm{pb}$ are set on B masses between $170$ and $450~\mathrm{GeV}$ for X boson masses between $20$ to $70~\mathrm{GeV}$. Through event selections that are optimized for vector-like quarks, the search results extend the reach for new particles to a previously unexplored phase space.