Collider Prospects for Muon $g-2$ in General Two Higgs Doublet Model

Abstract

Recent progress on muon $g-2$ 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, ${\rho }_{\tau \mu }={\rho }_{\mu \tau }$, 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 ${\rho }_{tt}$ and find that LHC search for $gg\to H,A\to \tau \mu$ gives more stringent bound than from $\tau \to \mu \gamma$ with two-loop mechanism. Turning on a second extra top Yukawa coupling, ${\rho }_{tc}$, can loosen the bound on ${\rho }_{tt}$, but LHC constraints can again be more stringent than from $B\to D\mu \nu$ vs $De\nu$ universality. This means that evidence for $H,A\to \tau \mu$ may yet emerge with full LHC Run 2 data, while direct search for ${\tau }^{\pm }{\mu }^{\mp }b{W}^{+}$ or $t\bar{c}b{W}^{+}$ (plus conjugate) may also bear fruit.

Comments: 7 pages, 5 captioned figures; accepted in PRD