Search for heavy H$\gamma$ and Z$\gamma$ resonances with a bottom quark-antiquark pair in the final state in proton-proton collisions at $\sqrt{s}$ = 13 TeV

Abstract

A search for heavy resonances decaying into a Higgs boson (H) or a Z boson and a photon ($\gamma$), with the H or Z bosons decaying to a bottom quark-antiquark pair ($\mathrm{b\bar{b}}$) is presented. The analysis is performed using proton-proton collision data at $\sqrt{s}$ = 13 TeV collected by the CMS experiment at the CERN Large Hadron Collider, corresponding to an integrated luminosity of 138 fb$^{-1}$. The analyzed events contain a photon and a massive large-radius jet originating from a Lorentz-boosted $\mathrm{b\bar{b}}$ system. An advanced transformer-based algorithm classifies jets according to their substructure and quark flavors, forming a tagger that identifies jets as candidates from H/Z $\to$ $\mathrm{b\bar{b}}$ decays. A set of parametric functions is used to fit the photon-jet invariant mass spectrum and to extract potential signals. No significant excess is observed above the standard model expectations. The results set upper limits at 95% confidence level on the product of the cross section and the branching fraction for spin-1 H$\gamma$ resonances and spin-0 Z$\gamma$ resonances, below 0.1 and 0.3 fb, respectively, representing the most stringent limits to date.