A powerful tool for measuring Higgs boson associated Lepton Flavour Violation

TL;DR

This paper explores the potential of an electron-photon collider to detect Higgs-mediated Lepton Flavour Violation, offering a promising method that surpasses current experiments in sensitivity and allows chirality measurements.

Contribution

It introduces a novel collider-based approach to search for Higgs-mediated LFV processes, demonstrating its superior sensitivity and capability to measure coupling chirality.

Findings

Significant production cross sections for LFV processes at the collider.

Projected bounds on LFV couplings are better than current experiments.

Ability to determine chirality of LFV couplings through polarization.

Abstract

In models with extended Higgs sectors, Higgs-boson-mediated Lepton Flavour Violation (LFV) can naturally appear. We study the physics potential of an electron-photon collider %as an option of the International Linear Collider on searching LFV processes $e^-\gamma\to\ell^-\varphi (\ell=\mu,\tau; \varphi=H, A)$ where $H$ and $A$ are extra CP even and odd Higgs bosons, respectively, in the minimal supersymmetric standard model and the effective two Higgs doublet model. The production cross section can be significantly large for the maximal allowed values of the LFV coupling constants under the current experimental data. Present experimental upper bounds on the effective LFV coupling constants would be considerably improved by searching these processes, which would be better than MEG and COMET experiments and also those at LHCb and SuperKEKB. Moreover, one can separately measure chirality of effective LFV coupling constants via these processes by selecting electron polarizations.