Spin-analysis of s-channel diphoton resonances at the LHC

TL;DR

This paper proposes a method to distinguish between spin-2 and spin-0 resonances in diphoton events at the LHC using angular asymmetry analysis, aiding the identification of new physics beyond the standard model.

Contribution

It introduces an angular analysis technique using the $A_{CE}$ asymmetry to differentiate spin hypotheses for diphoton resonances at the LHC, including next-to-leading order QCD corrections.

Findings

The $A_{CE}$ asymmetry effectively discriminates between spin-2 and spin-0 resonances.

Next-to-leading order QCD calculations improve the accuracy of the angular analysis.

The method enhances the ability to identify the nature of new high-mass resonances.

Abstract

The high mass neutral quantum states envisaged by theories of physics beyond the standard model can at the hadron colliders reveal themselves through their decay into a pair of photons. Once such a peak in the diphoton invariant mass distribution is discovered, the determination of its spin through the distinctive photon angular distributions is needed in order to identify the associated nonstandard dynamics. We here discuss the discrimination of the spin-2 Randall-Sundrum graviton excitation against the hypothesis of a spin-0 exchange giving the same number of events under the peak, by means of the angular analysis applied to resonant diphoton events expected to be observed at the LHC. The spin-0 hypothesis is modelled by an effective interaction of a high mass gauge singlet scalar particle interacting with the standard model fields. The basic observable of our analysis is the symmetrically integrated angular asymmetry $A_{CE}$, calculated for both graviton and scalar s-channel exchanges to next-to-leading order in QCD.