Search for a heavy resonance decaying into a top quark and a W boson in the lepton+jets final state at $\sqrt{s} = $13 TeV

TL;DR

This paper reports a search for heavy resonances decaying into a top quark and W boson at 13 TeV, setting new limits on models predicting such particles using CMS data and advanced jet tagging techniques.

Contribution

It introduces a novel top quark tagging method with jet clustering and grooming, extending the resonance mass search range and providing the most stringent limits on the b* model to date.

Findings

Excluded b* quark masses up to 3.2 TeV at 95% CL.

Extended the resonance mass search range down to 0.7 TeV.

Set new upper cross section limits on heavy resonance models.

Abstract

A search for a heavy resonance decaying into a top quark and a W boson in proton-proton collisions at $\sqrt{s} =$ 13 TeV is presented. The data analyzed were recorded with the CMS detector at the LHC and correspond to an integrated luminosity of 138 fb$^{-1}$. The top quark is reconstructed as a single jet and the W boson, from its decay into an electron or muon and the corresponding neutrino. A top quark tagging technique based on jet clustering with a variable distance parameter and simultaneous jet grooming is used to identify jets from the collimated top quark decay. The results are interpreted in the context of two benchmark models, where the heavy resonance is either an excited bottom quark b$^*$ or a vector-like quark B. A statistical combination with an earlier search by the CMS Collaboration in the all-hadronic final state is performed to place upper cross section limits on these two models. The new analysis extends the lower range of resonance mass probed from 1.4 down to 0.7 TeV. For left-handed, right-handed, and vector-like couplings, b$^*$ masses up to 3.0, 3.0, and 3.2 TeV are excluded at 95% confidence level, respectively. The observed upper limits represent the most stringent constraints on the b$^*$ model to date.