A $\gamma\gamma$ Collider for the 750 GeV Resonant State

TL;DR

This paper proposes using a gamma-gamma collider to study the 750 GeV resonance, enabling verification of its existence, measurement of its properties, and determination of its spin and decay channels beyond what current LHC data provides.

Contribution

It introduces the concept of a gamma-gamma collider as a tool to explore the properties of the 750 GeV resonance, including its production, decay modes, and spin, complementing LHC measurements.

Findings

Gamma-gamma collider can verify the 750 GeV resonance.

It can measure branching fractions of the resonance to various vector bosons.

Angular distributions can determine the resonance's spin (0 or 2).

Abstract

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