A $γγ$ Collider for the 750 GeV Resonant State

Abstract

Recent data collected by ATLAS and CMS at 13 TeV collision energy of the LHC indicate the existence of a new resonant state $ϕ$ with a mass of 750 GeV decaying into two photons $γγ$. The properties of $ϕ$ should be studied further at the LHC and also future colliders. Since only $ϕ\to γγ$ decay channel has been measured, one of the best ways to extract more information about $ϕ$ is to use a $γγ$ collider to produce $ϕ$ at the resonant energy. In this work we show how a $γγ$ collider helps to verify the existence of $ϕ$ and to provide some of the most important information about the properties of $ϕ$, such as branching fractions of $ϕ\to V_1V_2$. Here $V_i$ can be $γ$, $Z$, or $W^\pm$. We also show that by studying angular distributions of the final $γ$'s in $γγ\to ϕ\to γγ$, one can obtain crucial information about whether this state is a spin-0 or a spin-2 state.