Search for a singly produced third-generation scalar leptoquark decaying to a $\tau$ lepton and a bottom quark in proton-proton collisions at $\sqrt{s} =$ 13 TeV

TL;DR

This paper reports a search for third-generation scalar leptoquarks decaying to a tau lepton and a bottom quark using 13 TeV proton-proton collision data, setting mass exclusion limits up to 740 GeV.

Contribution

It presents the first search for singly produced third-generation scalar leptoquarks decaying to tau and bottom quarks at 13 TeV, establishing new exclusion limits.

Findings

Excluded scalar leptoquark masses below 740 GeV for unit Yukawa coupling.

Set upper limits on production cross section as a function of mass.

Provided the best mass limits for large Yukawa couplings above 1.4.

Abstract

A search is presented for a singly produced third-generation scalar leptoquark decaying to a $\tau$ lepton and a bottom quark. Associated production of a leptoquark and a $\tau$ lepton is considered, leading to a final state with a bottom quark and two $\tau$ leptons. The search uses proton-proton collision data at a center-of-mass energy of 13 TeV recorded with the CMS detector, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Upper limits are set at 95% confidence level on the production cross section of the third-generation scalar leptoquarks as a function of their mass. From a comparison of the results with the theoretical predictions, a third-generation scalar leptoquark decaying to a $\tau$ lepton and a bottom quark, assuming unit Yukawa coupling ($\lambda$), is excluded for masses below 740 GeV. Limits are also set on $\lambda$ of the hypothesized leptoquark as a function of its mass. Above $\lambda =$ 1.4, this result provides the best upper limit on the mass of a third-generation scalar leptoquark decaying to a $\tau$ lepton and a bottom quark.