Higgs FCNC h -> t* c decay at the muon collider

TL;DR

This paper explores the potential of future muon colliders to detect flavor-changing neutral current decays involving the Higgs and top quark, focusing on rare decay modes that could reveal new physics beyond the Standard Model.

Contribution

It assesses the discovery prospects of Higgs FCNC decays at muon colliders and compares their sensitivity to the LHC, highlighting the potential to probe new physics scenarios.

Findings

Muon colliders can test h -> t* c decays down to g_tc=0.5

LHC can probe smaller g_tc values, but may be affected by background

Rare decay modes could reveal physics beyond the Standard Model

Abstract

We study the discovery potential of the flavor-changing neutral coupling (FCNC) htc of the Higgs boson and the top quark through the rare tree-body decay h -> Wbc at Muon colliders for a light Higgs boson with mass 114 < m_h < 145 GeV. This decay mode may compete with the SM background induced by the hWW coupling in some models with a tree-level htc coupling and with models that predict this coupling at the one-loop level in the range 10^{-2} - 10^{-1}. A future muon collider could test the scalar FCNC decay t -> hc via Higgs decay h -> t* c -> b W+ c down to values of the coupling g_{tc}=0.5 (that are equivalent to BR(t -> hc) = 5 x 10^{-3}). The LHC could probe values of g_{tc} one order of magnitude smaller, unless other processes beyond the SM appear that through intense multi jet activity may clutter the t -> hc signal.