Search for pair-produced vector-like leptons in final states with third-generation leptons and at least three b quark jets in proton-proton collisions at $\sqrt{s}$ = 13 TeV

TL;DR

This paper reports the first search for vector-like leptons within the 4321 model at the LHC, analyzing 96.5 fb$^{-1}$ of proton-proton collision data to set upper limits on VLL production and observe a 2.8 sigma excess at 600 GeV.

Contribution

It introduces the first search for VLLs in the 4321 model using CMS data, providing new constraints on VLL masses and production cross sections.

Findings

Upper limits set on VLL production cross section for masses 500-1050 GeV.

A 2.8 sigma excess observed at 600 GeV VLL mass point.

Observed limits are roughly twice the expected limits.

Abstract

The first search is presented for vector-like leptons (VLLs) in the context of the "4321 model", an ultraviolet-complete model with the potential to explain existing B physics measurements that are in tension with standard model predictions. The analyzed data, corresponding to an integrated luminosity of 96.5 fb$^{-1}$, were recorded in 2017 and 2018 with the CMS detector at the LHC in proton-proton collisions at $\sqrt{s}$ = 13 TeV. Final states with ${\geq}$ 3 b-tagged jets and two third-generation leptons ($\tau\tau$, $\tau\nu_\tau$, or $\nu_\tau\nu_\tau$) are considered. Upper limits are derived on the VLL production cross section in the VLL mass range 500-1050 GeV. The maximum likelihood fit prefers the presence of signal at the level of 2.8 standard deviations, for a representative VLL mass point of 600 GeV. As a consequence, the observed upper limits are approximately double the expected limits.