Search for high-mass Z-gamma resonances in e+e-gamma and mu+mu-gamma final states in proton-proton collisions at sqrt(s) = 8 and 13 TeV

TL;DR

This study searches for high-mass scalar particles decaying into Z bosons and photons in proton-proton collisions at 8 and 13 TeV, finding no significant signals and setting upper limits on production cross sections.

Contribution

First search for high-mass Z-gamma resonances in e+e-gamma and mu+mu-gamma final states at LHC energies, providing new constraints on such particles.

Findings

No significant deviation from the standard model observed.

Upper limits on production cross section range from 280 to 20 fb.

Search covers resonance masses from 200 to 2000 GeV.

Abstract

This paper describes the search for a high-mass narrow-width scalar particle decaying into a Z boson and a photon. The analysis is performed using proton-proton collision data recorded with the CMS detector at the LHC at center-of-mass energies of 8 and 13 TeV, corresponding to integrated luminosities of 19.7 and 2.7 inverse femtobarns, respectively. The Z bosons are reconstructed from opposite-sign electron or muon pairs. No statistically significant deviation from the standard model predictions has been found in the 200-2000 GeV mass range. Upper limits at 95% confidence level have been derived on the product of the scalar particle production cross section and the branching fraction of the Z decaying into electrons or muons, which range from 280 to 20 fb for resonance masses between 200 and 2000 GeV.