Search for a heavy resonance decaying into a Z and a Higgs boson in events with an energetic jet and two electrons, two muons, or missing transverse momentum in proton-proton collisions at $\sqrt{s}$ = 13 TeV

TL;DR

This paper reports a search for heavy resonances decaying into Z and Higgs bosons at 13 TeV, utilizing advanced machine learning techniques to improve detection sensitivity for high-mass particles in various decay channels.

Contribution

It introduces a novel analysis employing machine-learning flavour-tagging to enhance sensitivity to high-mass resonances decaying into Z and Higgs bosons, especially in channels not previously explored.

Findings

No significant excess observed, setting limits on resonance production.

Enhanced sensitivity for resonance masses between 1.4 and 5 TeV.

Improved detection in channels with at most one b quark tag.

Abstract

A search is presented for a heavy resonance decaying into a Z boson and a Higgs (H) boson. The analysis is based on data from proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138 fb$^{-1}$, recorded with the CMS experiment in the years 2016-2018. Resonance masses between 1.4 and 5 TeV are considered, resulting in large transverse momenta of the Z and H bosons. Final states that result from Z boson decays to pairs of electrons, muons, or neutrinos are considered. The H boson is reconstructed as a single large-radius jet, recoiling against the Z boson. Machine-learning flavour-tagging techniques are employed to identify decays of a Lorentz-boosted H boson into pairs of charm or bottom quarks, or into four quarks via the intermediate H $\to$ WW* and ZZ* decays. The analysis targets H boson decays that were not generally included in previous searches using the H $\to$ $\mathrm{b\bar{b}}$ channel. Compared with previous analyses, the sensitivity for high resonance masses is improved significantly in the channel where at most one b quark is tagged.