Is it $SU(2)_{\mathrm{L}}$ or just $U(1)_{\mathrm{Y}}$? $750$ GeV di-photon probes of the electroweak nature of new states

TL;DR

This paper investigates how a 750 GeV di-photon resonance could reveal the electroweak quantum numbers of new particles beyond the Standard Model by analyzing specific decay modes at the LHC.

Contribution

It proposes a method to determine the electroweak nature of new states through decay measurements of the resonance, including effects of mixing with the Higgs.

Findings

Robust LHC luminosity estimates for discovering decay modes

Constraints on electroweak quantum numbers of new particles

Implications of Higgs mixing on decay signatures

Abstract

The existence of a 750 GeV di-photon spin-0 resonance $S$ would imply the additional presence of new particles beyond the Standard Model, coupling directly to $S$ and electromagnetically charged. For an $SU(2)_{\mathrm{L}}$ singlet $S$, we explore the possibility of probing the $SU(2)_{\mathrm{L}}$ and $U(1)_{\mathrm{Y}}$ quantum numbers of the new states at the LHC by measuring/constraining the $WW$, $Z\gamma$ and $ZZ$ decays of $S$. We obtain robust prospects on the required LHC integrated luminosity to discover the new decay modes of $S$, and discuss the implications of these measurements for probing the electroweak nature of the new states. We also discuss the impact of $S$ mixing with the SM Higgs in such probes.