Search for heavy resonances decaying into a $W$ or $Z$ boson and a Higgs boson in final states with leptons and $b$-jets in 36 fb$^{-1}$ of $\sqrt s = 13$ TeV $pp$ collisions with the ATLAS detector

TL;DR

This paper reports a search for new heavy resonances decaying into a W or Z boson and a Higgs boson using 36.1 fb$^{-1}$ of 13 TeV proton-proton collision data from ATLAS, finding no significant signals and setting upper limits on production cross-sections.

Contribution

First search to analyze multiple final states for heavy resonances decaying into W/Z and Higgs bosons at 13 TeV with ATLAS, providing new constraints on theoretical models.

Findings

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

Upper limits on production cross-section range from 9.0×10⁻⁴ pb to 0.81 pb.

Constraints placed on heavy-vector-triplet and two-Higgs-doublet models.

Abstract

A search is conducted for new resonances decaying into a $W$ or $Z$ boson and a 125 GeV Higgs boson in the $\nu\bar{\nu}b\bar{b}$, $\ell^{\pm}{\nu}b\bar{b}$, and $\ell^+\ell^-b\bar{b}$ final states, where $\ell^{\pm}= e^{\pm}$ or $\mu^{\pm}$, in $pp$ collisions at $\sqrt{s} = 13$ TeV. The data used correspond to a total integrated luminosity of 36.1 fb$^{-1}$ collected with the ATLAS detector at the Large Hadron Collider during the 2015 and 2016 data-taking periods. The search is conducted by examining the reconstructed invariant or transverse mass distributions of $Wh$ and $Zh$ candidates for evidence of a localised excess in the mass range of 220 GeV up to 5 TeV. No significant excess is observed and the results are interpreted in terms of constraints on the production cross-section times branching fraction of heavy $W^\prime$ and $Z^\prime$ resonances in heavy-vector-triplet models and the CP-odd scalar boson $A$ in two-Higgs-doublet models. Upper limits are placed at the 95% confidence level and range between $9.0\times 10^{-4}$ pb and $8.1\times 10^{-1}$ pb depending on the model and mass of the resonance.