Constraining the SMEFT with a differential cross section measurement of $tWZ$ production at the HL-LHC

Abstract: A prospective measurement of the differential cross section of \tWZ production with respect to the transverse momentum of the \PZ boson using a general-purpose detector at the High-Luminosity Large Hadron Collider (HL-LHC) is described. The response of a general-purpose detector at the HL-LHC is simulated and used to estimate the uncertainties and covariances of the differential cross section measurement. Constraints on the Standard Model Effective Field Theory (SMEFT) enabled by the measurement are estimated. A parametric model of the differential cross section in the SMEFT is constructed and is used to determine the expected posterior probability function of six SMEFT Wilson coefficients and the expected 95\% Bayesian credible intervals for each coefficient and pair of coefficients. The intervals suggest that for all coefficients, the measurement will provide competitive but weaker constraints than those derived from other \mbox{HL-LHC} measurements involving top quarks and \PZ bosons. However, as the measurement is simultaneously sensitive to to a unique set of SMEFT coefficients, it will provide a useful input to a global SMEFT analysis that considers many operators.