Further Studies of Higgs Properties at An ILC $\gamma\gamma$ Collider

TL;DR

This paper explores how a gamma-gamma collider can verify the Higgs boson's properties, especially its decay modes and spin, to confirm if it matches the Standard Model predictions or indicates new physics.

Contribution

It demonstrates the potential of a gamma-gamma collider to distinguish Higgs properties, such as decay rates and spin, complementing LHC findings and testing various theoretical models.

Findings

Gamma-gamma collider can confirm enhanced h→γγ decay rate.

Angular distribution analysis can determine Higgs spin.

Different models can be tested via h→γZ decay studies.

Abstract

Recently the ATLAS and CMS experiments at the LHC have found a Higgs like boson $h$ with a mass around 125 GeV from several decay modes. The decay mode $h \to \gamma\gamma$ is one of the most important modes in studying whether $h$ is actually the standard model (SM) Higgs boson. Current data indicate that $h\to \gamma\gamma$ has a branching ratio larger than the SM prediction for $h$ being identified as the SM Higgs boson. To decide whether the $h$ discovered at the LHC is the SM Higgs boson, more data are needed. We study how $\gamma\gamma$ collider can help to provide some of the most important information about the Higgs boson properties. We show that a $\gamma\gamma$ collider can easily verify whether the enhanced $h \to \gamma\gamma$ observed at the LHC hold. Different models can be tested by studying Higgs boson decay to $\gamma Z$. Studying angular distribution of the $\gamma \gamma$ through on-shell production of $h$ and its subsequent decays into a $\gamma \gamma$ pair can decide whether the Higgs like boson $h$ at the LHC is a spin-0 or a spin-2 boson.