Charged lepton distributions as a probe of contact e+e-HZ interactions at a linear collider with polarized beams

TL;DR

This paper explores how charged lepton angular distributions in e+e- -> HZ processes can reveal new physics contact interactions, including CP violation, at a 500 GeV linear collider with polarized beams.

Contribution

It provides a comprehensive framework for analyzing general four-point e+e-HZ interactions, including CP violation, and studies their observable effects with polarized beams.

Findings

Identifies angular correlations sensitive to new contact interactions.

Estimates the collider's sensitivity to various form factors.

Includes effects of beam polarization on probing new physics.

Abstract

We examine very general four-point interactions arising from new physics and contributing to the Higgs production process e+e- -> HZ. We write all possible forms for these interactions consistent with Lorentz invariance. We allow the possibility of CP violation. Contributions to the process from anomalous ZZH and gamma ZH interactions studied earlier arise as a special case of our four-point amplitude. We consider the decay of Z into a charged lepton pair and obtain expressions for angular distributions of charged leptons arising from the interference of the four-point contribution with the standard-model contribution. We take into account possible longitudinal or transverse beam polarization likely to be available at a linear collider. We examine several correlations which can be used to study the various form factors present in the e+e-HZ contact interactions. We also obtain the sensitivity of these correlations in constraining the new-physics interactions at a linear collider operating at a centre-of-mass energy of 500 GeV with longitudinal or transverse polarization.