Search for excited quarks inqq¯→γγat the CERN LHC

If quarks are composite particles, then excited states are expected to play a rôle in the Large Hadron Collider phenomena. Concentrating on virtual effects, and using a large part of the compact muon solenoid detection criteria, we present here a realistic examination of their effect in diphoton production at the CERN 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, $\Lambda \le 1.55(2.95)$ can be excluded at 99% CL with 30 $(200){\mathrm{fb}}^{-1}$ integrated luminosity.