Higgs couplings in SMEFT via Zh production at the HL-LHC

Abstract

We study the Higgs couplings involved in the $Zh$ associated production mode at the Large Hadron Collider (LHC) in presence of Higgs-gauge boson coupling modifiers via $κ$ framework, and dimension 6 Standard Model Effective Theory (SMEFT) operators. The analysis is performed mainly in context of the HL-LHC (with $\sqrt{s}=$14 TeV and luminosity 3000 $fb^{-1}$) setup using cut based as well as machine learning techniques. The analysis shows significant betterment in the signal significance by using the machine learning technique. We also do a $χ^2$ analysis, which reveals an appreciable change in the sensitivity of the coupling modifiers due to the presence of effective operators, in particular due to the $qqZh$ Higgs-current interactions. The dipole operators concerning the same vertex, combine quarks of different chiralities and does not interfere with the SM diagrams, hence contributing only at $\mathcal{O} (Λ^{-4})$. In order to observe better sensitivity for this class of operators, we need to move to higher center-of-mass energy, where the effects of both Higgs-current and dipole 4-point interactions are more prominent.