Constraining Type II 2HDM in Light of LHC Higgs Searches

TL;DR

This paper examines how LHC Higgs search results constrain the parameter space of the Type II Two Higgs-Doublet Model, analyzing scenarios where the 126 GeV Higgs is either the light or heavy CP-even Higgs, and identifying viable regions consistent with experimental data.

Contribution

It provides a detailed analysis of the parameter space of the Type II 2HDM under LHC constraints, considering both light and heavy Higgs interpretations of the 126 GeV signal, and explores correlations among different Higgs decay channels.

Findings

Narrow allowed regions for $ aneta$ and $eta- ext{alpha}$ in both scenarios.

Mass parameters $m_A$ and $m_{H^ ext{pm}}$ are constrained by $ ho$ and flavor physics.

Strong correlation between $ ext{gamma} ext{gamma}$ and $VV$ channels in the allowed parameter space.

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.