Constraining Type II 2HDM in Light of LHC Higgs Searches

Abstract

We study the implication of the LHC Higgs search results on the Type II Two Higgs-Doublet Model. In particular, we explore the scenarios in which the observed 126 GeV Higgs signal is interpreted as either the light CP-even Higgs $h^0$ or the heavy CP-even Higgs $H^0$. Imposing both theoretical and experimental constraints, we analyze the surviving parameter regions in $m_H$ ($m_h$), $m_A$, $m_{H^\pm}$, $\tan\beta$ and $\sin(\beta - \alpha)$. We further identify the regions that could accommodate a 126 GeV Higgs with cross sections consistent with the observed Higgs signal. We find that in the $h^0$-126 case, we are restricted to narrow regions of $\sin(\beta-\alpha) \approx \pm 1$ with $\tan\beta$ up to 4, or an extended region with $0.55 < \sin(\beta-\alpha) < 0.9$ and $1.5 < \tan\beta < 4$. The values of $m_H$, $m_A$ and $m_{H^\pm}$, however, are relatively unconstrained. In the $H^0$-126 case, we are restricted to a narrow region of $\sin(\beta-\alpha) \sim 0$ with $\tan\beta$ up to about 8, or an extended region of $\sin(\beta-\alpha) $ between $-0.8$ to $-0.05$, with $\tan\beta$ extended to 30 or higher. $m_A$ and $m_{H^\pm}$ are nearly degenerate due to $\Delta\rho$ constraints. Imposing flavor constraints shrinks the surviving parameter space significantly for the $H^0$-126 case, limiting $\tan\beta \lesssim 10$, but has little effect in the $h^0$-126 case. We also investigate the correlation between $\gamma\gamma$, $VV$ and $bb/\tau\tau$ channels. $\gamma\gamma$ and $VV$ channels are most likely to be highly correlated with $\gamma\gamma:VV \sim 1$ for the normalized cross sections.