# Search for third-generation scalar leptoquarks decaying to a top quark and a $\tau$ lepton at $\sqrt{s}=$ 13 TeV

## TL;DR

This paper reports a search for third-generation scalar leptoquarks decaying into a top quark and a tau lepton using 13 TeV proton-proton collision data, setting new mass exclusion limits up to 900 GeV.

## Contribution

It presents the most stringent limits to date on scalar leptoquark production decaying to top quarks and tau leptons, based on CMS data at 13 TeV.

## Key findings

- No evidence for leptoquark pair production was observed.
- Masses below 900 GeV are excluded at 95% confidence level.
- The analysis improves previous limits on third-generation scalar leptoquarks.

## Abstract

A search for pair production of heavy scalar leptoquarks (LQs), each decaying into a top quark and a $\tau$ lepton, is presented. The search considers final states with an electron or a muon, one or two $\tau$ leptons that decayed to hadrons, and additional jets. The data were collected in 2016 in proton-proton collisions at $\sqrt{s}=$ 13 TeV with the CMS detector at the LHC, and correspond to an integrated luminosity of 35.9 fb$^{-1}$. No evidence for pair production of LQs is found. Assuming a branching fraction of unity for the decay LQ$ \to $t$\tau$, upper limits on the production cross section are set as a function of LQ mass, excluding masses below 900 GeV at 95% confidence level. These results provide the most stringent limits to date on the production of scalar LQs that decay to a top quark and a $\tau$ lepton.