Higgcision in the Two-Higgs Doublet Models

We perform global fits to general two-Higgs doublet models (2HDMs) with generalized couplings using the most updated data from ATLAS, CMS, and Tevatron. We include both scenarios with CP-conserving and CP-violating couplings. By relaxing the requirement on the discrete symmetries that are often imposed on the Yukawa couplings, we try to see which of the 2HDMs is preferred. We found that (i) Higgcision in 2HDMs can be performed efficiently by using only 4 parameters including the charged Higgs contributions to the Higgs couplings to two photons, (ii) the differences among various types of 2HDMs are very small with respect to the chi-square fits, (iii) $\tan\beta$ is constrained to be small, (iv) the $p$-values for various fits in 2HDMs are worse than that of the standard model. Finally, we put emphasis on our findings that future precision measurements of the Higgs coupling to the scalar top-quark bilinear ($C_u^S$) and $\tan\beta$ may endow us with the discriminating power among various types of 2HDMs especially when $C_u^S$ deviates from its SM value 1.Comment: 46 pages, 4 tables, 22 figures, references added, to appear in JHE

Enhanced Charged Higgs Production through W-Higgs Fusion in W-b Scattering

We study the associated production of a charged Higgs boson with a bottom quark and a light quark at the LHC via p p \to H^\pm\,b\,j in the Two Higgs Doublet Models (2HDMs). Using the effective W approximation, we show that there is exact cancellation among various Feynman diagrams in high energy limit. This may imply that the production of charged Higgs can be significantly enhanced in the presence of large mass differences among the neutral Higgs bosons via W^\pm-Higgs fusion in the p p \to H^\pm\,b\,j process. Particularly, we emphasize the potential enhancement due to a light pseudoscalar boson $A$, which is still allowed by the current data by which we explicitly calculate the allowed regions in (M_A,\,\tan\beta) plane, and show that the production cross section can be as large as 0.1 pb for large $\tan\beta$. We also show that the transverse momentum distribution of the b quark can potentially distinguish the W^\pm-A fusion diagram from the top diagram. Finally, we point out further enhancement when we go beyond the 2HDMs.Comment: 25 pages, 9 pdf figures, Matches the published JHEP versio

Entangling Higgs production associated with a single top and a top-quark pair in the presence of anomalous top-Yukawa coupling

The ATLAS and CMS collaborations observed a mild excess in the associated Higgs production with a top-quark pair ($t\bar t h$) and reported the signal strengths of $\mu_{tth}^{\rm ATLAS}=1.81\pm 0.80$ and $\mu_{tth}^{\rm CMS}=2.75\pm 0.99$ based on the data collected at $\sqrt{s}$= 7 and 8 TeV. Although, at the current stage, there is no obvious indication whether the excess is real or due to statistical fluctuations, here we perform a case study of this mild excess by exploiting the strong entanglement between the associated Higgs production with a single top quark ($thX$) and $t\bar t h$ production in the presence of anomalous top-Yukawa coupling. As well known, $t\bar t h$ production only depends on the absolute value of the top-Yukawa coupling. Meanwhile, in $thX$ production, this degeneracy is lifted through the strong interference between the two main contributions which are proportional to the top-Yukawa and the gauge-Higgs couplings, respectively. Especially, when the relative sign of the top-Yukawa coupling with respect to the gauge-Higgs coupling is reversed, the $thX$ cross section can be enhanced by more than one order of magnitude. We perform a detailed study of the influence of $thX$ production on $t\bar{t}h$ production in the presence of the anomalous top-Yukawa coupling and point out that it is crucial to include $thX$ production in the analysis of the $t\bar t h$ data to pin down the sign and the size of the top-Yukawa coupling in future. While assuming the Standard Model (SM) value for the gauge-Higgs coupling, we vary the top-Yukawa coupling within the range allowed by the current LHC Higgs data. We consider the Higgs decay modes into multileptons, $b\bar b$ and $\gamma\gamma$ putting a particular emphasis on the same sign dilepton events. We also discuss ...Comment: 32 pages, 10 figures, 12 tables, to appear in JHE

Confronting Higgcision with Electric Dipole Moments

Current data on the signal strengths and angular spectrum of the 125.5 GeV Higgs boson still allow a CP-mixed state, namely, the pseudoscalar coupling to the top quark can be as sizable as the scalar coupling: $C_u^S \approx C_u^P =1/2$. CP violation can then arise and manifest in sizable electric dipole moments (EDMs). In the framework of two-Higgs-doublet models, we not only update the Higgs precision (Higgcision) study on the couplings with the most updated Higgs signal strength data, but also compute all the Higgs-mediated contributions from the 125.5 GeV Higgs boson to the EDMs, and confront the allowed parameter space against the existing constraints from the EDM measurements of Thallium, neutron, Mercury, and Thorium monoxide. We found that the combined EDM constraints restrict the pseudoscalar coupling to be less than about $10^{-2}$, unless there are contributions from other Higgs bosons, supersymmetric particles, or other exotic particles that delicately cancel the current Higgs-mediated contributions.Comment: 34 pages, 17 figures, to appear in JHE