Search for heavy resonances decaying into a $Z$ or $W$ boson and a Higgs boson in final states with leptons and $b$-jets in $139~$fb$^{-1}$ of $pp$ collisions at $\sqrt{s}=13~$TeV with the ATLAS detector

TL;DR

This paper reports a search for new heavy resonances decaying into a Z or W boson and a Higgs boson using 139 fb$^{-1}$ of proton-proton collision data at 13 TeV, finding no significant signals and setting upper limits on production cross sections.

Contribution

First search to analyze a wide mass range for heavy resonances decaying into Z/W and Higgs bosons in multiple final states with leptons and b-jets at 13 TeV.

Findings

No significant excess observed in the mass range from 220 GeV to 5 TeV.

Placed upper limits on production cross sections between 1.3 pb and 0.3 fb.

Constraints placed on Heavy Vector Triplet and two-Higgs-doublet models.

Abstract

This article presents a search for new resonances decaying into a $Z$ or $W$ boson and a 125 GeV Higgs boson $h$, and it targets the $\nu\bar{\nu}b\bar{b}$, $\ell^+\ell^-b\bar{b}$, or $\ell^{\pm}{\nu}b\bar{b}$ final states, where $\ell=e$ or $\mu$, in proton-proton collisions at $\sqrt{s}=13$ TeV. The data used correspond to a total integrated luminosity of 139 fb$^{-1}$ collected by the ATLAS detector during Run 2 of the LHC at CERN. The search is conducted by examining the reconstructed invariant or transverse mass distributions of $Zh$ or $Wh$ candidates for evidence of a localised excess in the mass range from 220 GeV to 5 TeV. No significant excess is observed and 95% confidence-level upper limits between 1.3 pb and 0.3 fb are placed on the production cross section times branching fraction of neutral and charged spin-1 resonances and CP-odd scalar bosons. These limits are converted into constraints on the parameter space of the Heavy Vector Triplet model and the two-Higgs-doublet model.