Exclusive Weak Radiative Higgs Decays in the Standard Model and Beyond

TL;DR

This paper investigates rare Higgs decays into mesons and gauge bosons, exploring their potential to reveal new physics effects like modified couplings and flavor violation, using QCD factorization.

Contribution

It provides a detailed analysis of exclusive Higgs decays to mesons and gauge bosons, highlighting their sensitivity to new physics effects including CP violation and flavor-changing couplings.

Findings

$h\to VZ$ decays are sensitive to $h\gamma Z$ couplings.

Measurement of $h\to\gamma Z$ helps determine CP-even and CP-odd couplings.

Some $h\to MW$ modes can probe flavor-violating Higgs interactions.

Abstract

We perform a detailed study of the exclusive Higgs decays $h\to MZ$ and $h\to MW$, where $M$ is a pseudoscalar or vector meson, using the QCD factorization approach. We allow for the presence of new-physics effects in the form of modified Higgs couplings to gauge bosons and fermions, including the possibility of flavor-changing Higgs couplings. We show that the decays $h\to VZ$ exhibit a strong sensitivity to the effective CP-even and CP-odd $h\gamma Z$ couplings. When combined with a measurement of the $h\to\gamma Z$ decay rate, this can be used to extract these couplings up to a sign ambiguity in the CP-odd coefficient. Some of the $h\to MW$ decay modes can be used to probe for flavor-violating Higgs couplings involving the top quark.