# Search for pair production of vector-like T and B quarks in single-lepton final states using boosted jet substructure in proton-proton collisions at sqrt(s) = 13 TeV

## TL;DR

This paper reports a search for vector-like T and B quarks in proton-proton collisions at 13 TeV, using boosted jet substructure techniques to identify decay products, setting new mass exclusion limits up to around 860 GeV.

## Contribution

It introduces advanced boosted jet substructure methods for detecting heavy vector-like quarks in single-lepton final states at the LHC.

## Key findings

- No excess over standard model background observed.
- Excluded T quark masses below 860 GeV in certain scenarios.
- Excluded B quark masses up to 730 GeV.

## Abstract

A search for pair production of massive vector-like T and B quarks in proton-proton collisions at sqrt(s) = 13 TeV is presented. The data set was collected in 2015 by the CMS experiment at the LHC and corresponds to an integrated luminosity of up to 2.6 inverse femtobarns. The T and B quarks are assumed to decay through three possible channels into a heavy boson (either a W, Z or Higgs boson) and a third generation quark. This search is performed in final states with one charged lepton and several jets, exploiting techniques to identify W or Higgs bosons decaying hadronically with large transverse momenta. No excess over the predicted standard model background is observed. Upper limits at 95% confidence level on the T quark pair production cross section are set that exclude T quark masses below 860 GeV in the singlet, and below 830 GeV in the doublet branching fraction scenario. For other branching fraction combinations with B(tH) + B(bW) >= 0.4, lower limits on the T quark range from 790 to 940 GeV. Limits are also set on pair production of singlet vector-like B quarks, which can be excluded up to a mass of 730 GeV. These limits are among the most stringent to date for vector-like T quarks. The techniques showcased here for understanding highly-boosted final states are important as the sensitivity to new particles is extended to higher masses.