Setting limits on quark Contact Interaction scales from ATLAS inclusive jet cross section measurements

Inclusive jet cross sections are one of the basic measurements from proton--proton (\textit{pp}) collider experiments such as the LHC, and can be used to test the Standard Model and search for new physics. We focus on the contact interaction (CI), a parametrisation of a potential beyond Standard Model process involving the flavour-symmetric \(q\bar{q} \rightarrow q\bar{q}\) interaction via an unknown intermediate state. Using CIJET, next to leading order (NLO) inclusive jet cross sections were computed for several contact interaction models at different scales \(\Lambda_{\mathrm{CI}}\), and exclusion limits were investigated by hypothesis testing on individual bins with the \(CL_s\) method. Further investigation, accounting for correlated systematic uncertainties across multiple bins, was carried out using the \texttt{pyhf} Python package to evaluate asymptotic formulas. Lower exclusion limits at the 95\% \(CL_s\) level for identical chirality color singlet \(q\bar{q}\) pairs were found to be \(\Lambda_{\mathrm{CI}} = 22.5\) TeV (single-bin \(CL_s\)) and \(\Lambda_{\mathrm{CI}} = 26.9\) TeV (\texttt{pyhf}). Weaker limits were found for mixed chirality and color octet states.