Search for excited quarks in the photon + jet final state in proton proton collisions at 13 TeV

The study presents a search for excited quarks $({\rm q^{\star}})$ decaying into a $\gamma+\mathrm{jet}$ final state at $\sqrt{s}=13\,\mathrm{TeV}$ with the CMS experiment, using the dataset corresponding to an integrated luminosity of $2.7\,\mathrm{fb^{-1}}$ collected during 2015 data taking at the LHC. High transverse momentum photons and $\mathrm{jets}$ are selected to search for a resonance peak in the continuous invariant mass distribution of $\gamma+\mathrm{jet}$. 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 mass $1.0 < M_{\mathrm q^{\star}} < 4.37\,\mathrm{TeV}$ and coupling strength $f=1.0$, and present exclusions of excited quark mass as a function of coupling strength.