CP-violating HWW couplings at the Large Hadron Collider

TL;DR

This paper explores how to detect CP-violating anomalous couplings in the HWW vertex at the LHC by analyzing specific decay channels and asymmetries, demonstrating the potential to measure these effects with current collider data.

Contribution

It introduces a method to probe CP-violating HWW couplings using kinematic distributions and asymmetries, validated with parton-level calculations and applicable at 14 TeV LHC.

Findings

Asymmetries can distinguish real and imaginary parts of the anomalous coupling.

Distributions are robust against showering and hadronisation effects.

Feasible measurement with 30-50 fb$^{-1}$ at 14 TeV.

Abstract

We investigate the possibility of probing an anomalous CP-violating coupling in the HWW vertex at the LHC. We consider the production of the Higgs in association of a W and then decay via the $H \rightarrow WW$ channel taking into account the limits on the Higgs production cross section from the Tevatron. We select the same-sign dilepton final state arising from leptonic decays of two of the three Ws and apply cuts required to suppress the standard model background. Several kinematical distributions and asymmetries that can be used to ascertain the presence of a non-zero anomalous coupling are presented. We find that, for Higgs mass in the range 130-150 GeV and anomalous couplings allowed by the Tevatron data, these distributions can be studied with an integrated luminosity of 30-50 fb$^{-1}$ at the 14 TeV run. Attention is specifically drawn to some asymmetries that enable one to probe the real and imaginary parts (as well as their signs) of the anomalous coupling, in a complementary manner. We also explicitly demonstrate that showering and hadronisation do not affect the utility of these variables, thus affirming the validity of parton level calculations.