Search for excited quarks in the photon + jet final state in proton proton collisions at 8 TeV

The paper presents a search for excited quarks $(q^{\star})$ decaying into a $\gamma+\mathrm{jet}$ final state at $\sqrt{s}=8\,\mathrm{TeV}$ with the CMS experiment, using the dataset corresponding to an integrated luminosity of $19.7\,\mathrm{fb^{-1}}$ collected during 2012 data taking at the LHC. Photons and $\mathrm{jets}$ with high transverse momentum are selected to search for a resonance peak in the $\gamma+\mathrm{jet}$ invariant mass distribution. The 95$\%$ confidence level upper limits on cross section times branching ratio are evaluated as a function of excited quark mass ($M_{\mathrm q^{\star}}$). We exclude at 95$\%$ CL excited quarks with $0.7 < M_{\mathrm q^{\star}} < 3.5\,\mathrm{TeV}$ for standard model couplings, and present exclusions of excited quark mass as a function of coupling strength.