Search for Excited Quarks in $q\bar{q} \to \gamma\gamma$ at the LHC

TL;DR

This paper investigates the potential effects of excited quarks on diphoton production at the LHC, providing limits on their properties based on simulated data and detection criteria.

Contribution

It offers a realistic analysis of excited quark effects in diphoton events at the LHC, including confidence limits on their parameters for various luminosities.

Findings

Excluded regions in the $\Lambda-M_{q*}$ parameter space at 99% CL.

For a 0.5 TeV excited quark, compositeness scale limits are set at $\Lambda \,\leq 1.55$ or 2.95 TeV depending on luminosity.

Provides a methodology for future searches of excited quarks in diphoton channels.

Abstract

If quarks are composite particles, then excited states are expected to play a r\^ole in the Large Hadron Collider phenomena. Concentrating on virtual effects, and using a large part of the CMS detection criteria, we present here a realistic examination of their effect in diphoton production at the LHC. For various luminosities, we present the 99 % confidence limit (CL) achievable in $\Lambda-M_{q*}$ parameter space where $\Lambda$ is the compositeness scale and M_{q^*} the mass of the state. For a q^* of mass 0.5 TeV, $\Lambda \leq 1.55 (2.95)$ can be excluded at 99% CL with 30 (200)${\rm fb}^{-1}$ integrated luminosity.