Collider prospects for the muon <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>g</mml:mi><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:math> in a general two-Higgs-doublet model
W.-S. Hou, Rishabh Jain, Chung Kao, Girish Kumar, Tanmoy Modak
Abstract
Recent progress on muon $g\ensuremath{-}2$ measurement prompts one to take it even more seriously. In the general two Higgs doublet model that allows extra Yukawa couplings, we take a simplified approach of single enhanced coupling. We fix the charged lepton flavor violating coupling, ${\ensuremath{\rho}}_{\ensuremath{\tau}\ensuremath{\mu}}={\ensuremath{\rho}}_{\ensuremath{\mu}\ensuremath{\tau}}$, via the one-loop mechanism, for illustrative masses of the heavy scalar $H$ and pseudoscalar $A$, where we assume ${m}_{A}={m}_{{H}^{+}}$. Since extra top Yukawa couplings are plausibly the largest, we turn on ${\ensuremath{\rho}}_{tt}$ and find that LHC search for $gg\ensuremath{\rightarrow}H,A\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{\mu}$ gives a more stringent bound than from $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\gamma}$ with the two-loop mechanism. Turning on a second extra top Yukawa coupling, ${\ensuremath{\rho}}_{tc}$, can loosen the bound on ${\ensuremath{\rho}}_{tt}$, but LHC constraints can again be more stringent than from $B\ensuremath{\rightarrow}D\ensuremath{\mu}\ensuremath{\nu}$ versus $De\ensuremath{\nu}$ universality. This means that evidence for $H,A\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{\mu}$ may yet emerge with full LHC Run 2 data, while direct search for ${\ensuremath{\tau}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\mu}}^{\ensuremath{\mp}}b{W}^{+}$ or $t\overline{c}b{W}^{+}$ (plus conjugate) may also bear fruit.