When the Higgs meets the Top: Search for t --> ch^0 at the LHC

TL;DR

This paper explores the potential for detecting the rare top quark decay t --> ch^0 at the LHC, considering implications of the Higgs boson and two Higgs doublet models, and suggests experimental search strategies.

Contribution

It proposes new search channels for t --> ch^0 decay in tar{t} events and discusses how existing data could constrain or reveal this decay mode.

Findings

Possible signals in h^0 decay modes like ZZ^*, \, \gamma\,\, and b\bar{b}

Existing data may already provide clues or limit the branching ratio

t --> ch^0 decay could occur at the percent level in certain models

Abstract

The newly discovered "Higgs" boson h^0, being lighter than the top quark t, opens up new probes for flavor and mass generation. In the general two Higgs doublet model, new ct, cc and tt Yukawa couplings could modify h^0 properties. If t --> ch^0 occurs at the percent level, the observed ZZ^* and \gamma\gamma signal events may have accompanying cbW activity coming from t\bar{t} feeddown. We suggest that t --> ch^0 can be searched for via h^0 --> ZZ^*, \gamma\gamma, WW^* and b\bar{b}, perhaps even \tau^+\tau^- modes in t\bar{t} events. Existing data might be able to reveal some clues for t --> ch^0 signature, or push the branching ratio B(t --> ch^0) down to below the percent level.