A panoramic study of K-factors for 111 processes at the 14 TeV LHC

In this comprehensive study, we investigate K-factors ( \(K=\sigma _{\text {NLO}}/\sigma _{\text {LO}}\equiv 1+\delta K\) $K={\sigma }_{\text{NLO}}/{\sigma }_{\text{LO}}\equiv 1+\delta K$ ) for a broad array of Standard Model processes at the 14 TeV LHC, which are pivotal for background assessments in Beyond the Standard Model (BSM) searches. Using MadGraph5_aMC@NLO, we calculate the leading-order and next-to-leading-order (NLO) cross-sections and compute the corresponding K-factors for 111 processes. Our analysis reveals K-factors ranging from 1.005 for \(pp \rightarrow jjj\) $pp\to jjj$ to 4.221 for \(pp\rightarrow W^\pm \gamma \gamma \gamma \) $pp\to W^{\pm }\gamma \gamma \gamma$ . Key findings include: (i) processes involving photons display significantly high K-factors, attributed to gluon-initiated processes at NLO; (ii) processes with multiple particle productions, particularly those involving vector bosons, exhibit elevated K-factors due to multiple real emission processes; (iii) there exists an inverse correlation between the number of jets and \(\delta K\) $\delta K$ , indicating that the addition of jets generally leads to a decrease in \(\delta K\) $\delta K$ . In addition, our investigation into differential K-factors relative to transverse momentum and invariant mass shows notable increases with higher \(p_T\) $p_T$ , but minimal changes with invariant mass. This study highlights the indispensable role of precise K-factor evaluations for accurate interpretations of BSM search outcomes.