Polarization-dependent observables in $H\to \ell^{+}\ell^{-} \gamma$ in the SM

TL;DR

This paper explores polarization-dependent observables in the rare Higgs decay to a lepton pair and a photon, proposing a framework to analyze their potential to reveal properties of the decay process and physics beyond the Standard Model.

Contribution

It introduces a comprehensive method to evaluate polarization-dependent observables in $H o ext{leptons} ext{and photon}$ decay, highlighting the significance of loop effects and polarization in probing new physics.

Findings

Polarization observables enhance sensitivity to resonance and non-resonance effects.

Loop contributions significantly influence polarization asymmetries.

Polarization analysis can help identify signatures of physics beyond the Standard Model.

Abstract

The rare three body decay of a Higgs boson to a lepton-anti lepton pair and a photon has begun to attract attention, after the first evidence for the $H\to Z\gamma$ at CMS and ATLAS, which is a sub process of $H \to \ell^+ \ell^- \gamma$ . To investigate some important features of this process, we suggest that the polarized forward-backward and the photon polarization asymmetries could be useful to probe its important properties, such as the behavior of Yukawa coupling, resonance, and non-resonance contributions. Our analysis introduces a comprehensive framework to evaluate the aforementioned polarization-dependent observables. By analyzing the polarization effects of the final-state photon and lepton separately on forward-backward asymmetries, we demonstrate that loop-induced contributions play a significant role to investigate these asymmetries. Unlike the unpolarized case, where the interference effects of resonance and non-resonance effects are minimal, we show that polarization dependent observables offer a powerful tool to analyze these features of this decay mode. Furthermore, these observables can provide a handy tool for probing possible signatures of physics beyond the SM.