A search for new resonances in multiple final states with a high transverse momentum $Z$ boson in $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector

TL;DR

This paper reports a search for new resonances in events with a high transverse momentum Z boson at 13 TeV, finding no significant excess and setting exclusion limits on potential new particles.

Contribution

It introduces a comprehensive search strategy using multiple event categories and invariant mass distributions to improve sensitivity to new resonances in Z boson events.

Findings

No significant excess observed in the data.

Exclusion limits set for Gaussian-shaped resonances and heavy vector triplet models.

Enhanced sensitivity achieved through multiple event categories.

Abstract

A generic search for resonances is performed with events containing a $Z$ boson with transverse momentum greater than 100 GeV, decaying into $e^+e^-$ or $\mu^+\mu^-$. The analysed data collected with the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider correspond to an integrated luminosity of 139 fb$^{-1}$. Two invariant mass distributions are examined for a localised excess relative to the expected Standard Model background in six independent event categories (and their inclusive sum) to increase the sensitivity. No significant excess is observed. Exclusion limits at 95% confidence level are derived for two cases: a model-independent interpretation of Gaussian-shaped resonances with the mass width between 3% and 10% of the resonance mass, and a specific heavy vector triplet model with the decay mode $W'\to ZW \to \ell\ell qq$.