Revisiting lepton-specific 2HDM in light of muon g-2 anomaly

TL;DR

This paper investigates the lepton-specific 2HDM as a potential explanation for the muon g-2 anomaly, considering various experimental and theoretical constraints, and identifies parameter regions compatible with both the anomaly and a strong first-order phase transition.

Contribution

It provides a comprehensive analysis of the parameter space of lepton-specific 2HDM explaining muon g-2 while satisfying multiple experimental constraints and exploring phase transition conditions.

Findings

Muon g-2 can be explained with specific parameter ranges.

Stringent limits from direct searches restrict the model.

Parameter regions allow for strong first-order phase transition.

Abstract

We examine the lepton-specific 2HDM as a solution of muon $g-2$ anomaly under various theoretical and experimental constraints, especially the direct search limits from the LHC and the requirement of a strong first-order phase transition in the early universe. We find that the muon g-2 anomaly can be explained in the region of 32 $<\tan\beta<$ 80, 10 GeV $<m_A<$ 65 GeV, 260 GeV $<m_H<$ 620 GeV and 180 GeV $<m_{H^\pm}<$ 620 GeV after imposing the joint constraints from the theory, the precision electroweak data, the 125 GeV Higgs data, the leptonic/semi-hadronic $\tau$ decays, the leptonic $Z$ decays and Br$(B_s \to \mu^+ \mu^-)$. The direct searches from the $h\to AA$ channels can impose stringent upper limits on Br$(h\to AA)$ and the multi-lepton event searches can sizably reduce the allowed region of $m_A$ and $\tan\beta$ (10 GeV $<m_A<$ 44 GeV and 32 $<\tan\beta<$ 60). Finally, we find that the model can produce a strong first-order phase transition in the region of 14 GeV $<m_A<$ 25 GeV, 310 GeV $<m_H<$ 355 GeV and 250 GeV $<m_{H^\pm}<$ 295 GeV, allowed by the explanation of the muon $g-2$ anomaly.