Constraining the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>t</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>u</mml:mi></mml:math> flavor changing neutral Higgs coupling at the LHC
W.-S. Hou, Ting-hsiang Hsu, Tanmoy Modak
Abstract
We study the constraints on $t\ensuremath{\rightarrow}u$ flavor changing neutral Higgs coupling and how it may be explored further at the LHC. In the general two Higgs doublet model, such transitions can be induced by a nonzero ${\ensuremath{\rho}}_{tu}$ Yukawa coupling. We show that such couplings can be constrained by existing searches at the LHC for ${m}_{H}$, ${m}_{A}$, and ${m}_{{H}^{+}}$ in the sub-TeV range, where $H$, $A$, and ${H}^{+}$ are the exotic $CP$-even, $CP$-odd, and charged scalars. We find that a dedicated $ug\ensuremath{\rightarrow}tH/tA\ensuremath{\rightarrow}tt\overline{u}$ search can probe the available parameter space of ${\ensuremath{\rho}}_{tu}$ down to a few percent level for $200\text{ }\text{ }\mathrm{GeV}\ensuremath{\lesssim}{m}_{H}$, ${m}_{A}\ensuremath{\lesssim}600\text{ }\text{ }\mathrm{GeV}$, with discovery possible at high luminosity. Effects of how other extra top Yukawa couplings, such as ${\ensuremath{\rho}}_{tc}$ and ${\ensuremath{\rho}}_{tt}$, dilute the sensitivity of the ${\ensuremath{\rho}}_{tu}$ probe are discussed.