Is the New Resonance Spin 0 or 2? Taking a Step Forward in the Higgs Boson Discovery

TL;DR

This paper proposes a method to determine whether the 125 GeV boson discovered at the LHC is a spin-0 or spin-2 particle by analyzing diphoton events, aiming for a 5-sigma confidence level.

Contribution

It introduces a center-edge asymmetry measure for diphoton angular distributions to distinguish the boson's spin and parity with high confidence.

Findings

Discrimination between scalar and tensor bosons achievable at 5σ confidence level.

Asymmetry method is robust against systematic uncertainties.

Combining ATLAS and CMS data enhances discrimination power.

Abstract

The observation of a new boson of mass $\sim 125\gev$ at the CERN LHC may finally have revealed the existence of a Higgs boson. Now we have the opportunity to scrutinize its properties, determining its quantum numbers and couplings to the standard model particles, in order to confirm or not its discovery. We show that by the end of the 8 TeV run, combining the entire data sets of ATLAS and CMS, it will be possible to discriminate between the following discovery alternatives: a scalar $J^P=0^+$ or a tensor $J^P=2^+$ particle with minimal couplings to photons, at a $5\sigma$ statistical confidence level at least, using only diphotons events. Our results are based on the calculation of a center-edge asymmetry measure of the reconstructed {\it sPlot} scattering polar angle of the diphotons. The results based on asymmetries are shown to be rather robust against systematic uncertainties with comparable discrimination power to a log likelihood ratio statistic.