Diagnosing Degenerate Higgs Bosons at 125 GeV

We develop diagnostic tools that would provide incontrovertible evidence for the presence of more than one Higgs boson near 125 GeV in the LHC data.Comment: 4 pages, 2 figure

Possible Explanation to Low CMB Quadrupole

The universe might experience many cycles with different vacua. The slow-roll inflation may be preceded by kinetic-dominated contraction occurring in "adjacent" vacua during some cycles. In this report we briefly show this phenomenon may lead to a cutoff of primordial power spectrum. Thus in some sense the CMB at large angular scale might encode the information of other vacua.Comment: 10 pages, 3 eps figures, accepted for publication in PRD, v2 revised with published versio

Two-Higgs-Doublet Models and Enhanced Rates for a 125 GeV Higgs

We examine the level of enhancement that can be achieved in the ZZ and \gamma\gamma channels for a two-Higgs-doublet model Higgs boson (either the light h or the heavy H) with mass near 125 GeV after imposing all constraints from LEP data, B physics, precision electroweak data, vacuum stability, unitarity and perturbativity. The latter constraints restrict substantially the possibilities for enhancing the gg -> h -> \gamma\gamma or gg -> H -> \gamma\gamma signal relative to that for the SM Higgs, hSM. Further, we find that a significant enhancement of the gg -> h -> \gamma\gamma or gg -> H -> \gamma\gamma signal in Type II models is possible only if the gg -> h -> ZZ or gg -> H -> ZZ mode is even more enhanced, a situation disfavored by current data. In contrast, in the Type I model one can achieve enhanced rates in the \gamma\gamma final state for the h while having the ZZ mode at or below the SM rate - the largest [gg -> h -> \gamma\gamma]/[gg -> hSM -> \gamma\gamma] ratio found is of order ~1.3 when the two Higgs doublet vacuum expectation ratio is tan\beta = 4 or 20 and the charged Higgs boson has its minimal LEP-allowed value of m_{H^\pm} = 90 GeV.Comment: 15 pages, 9 figure

Isospin-violating dark-matter-nucleon scattering via two-Higgs-doublet-model portals

We show that in a multi-Higgs model in which one Higgs fits the LHC 125 GeV state, one or more of the other Higgs bosons can mediate DM-nucleon interactions with maximal DM isospin violation being possible for appropriate Higgs-quark couplings, independent of the nature of DM. We then consider the explicit example of a Type II two-Higgs-doublet model, identifying the h or H as the 125 GeV state while the H or h, respectively, mediates DM-nucleon interactions. Finally, we show that if a stable scalar, S, is added then it can be a viable light DM candidate with correct relic density while obeying all direct and indirect detection limits.Comment: Two subsections are added to address the collider bounds from direct search for heavy Higgs bosons and from jet plus missing energy final states. The LUX (2013) bound considered in the previous version is replaced by the latest LUX (2016) bound and the SuperCDMS limit is taken into account. The conclusions remain unchanged. A very minor change made in the title and new references include

Radius stabilization and dark matter with a bulk Higgs in warped extra dimension

We employ an $SU(2)$ bulk Higgs doublet as the stabilization field in Randall-Sundrum model with appropriate bulk and brane-localized potentials. The gauge hierarchy problem can be solved for an exponentially IR-localized Higgs background field with mild values of fundamental parameters of the 5D theory. We consider an IR-UV-IR background geometry with the 5D SM fields in the bulk such that all the fields have even and odd tower of KK-modes. The zero-mode 4D effective theory contains all the SM fields plus a stable scalar, which serves as a dark matter candidate.Comment: 8 pages, 4 figures. Talk given at the XXXIX International Conference of Theoretical Physics "Matter To The Deepest", Ustron, Poland. Based on arXiv:1504.0370

Higgs Dark Matter from a Warped Extra-Dimension -- the truncated-inert-doublet model

We construct a 5D $\mathbb{Z}_2$-symmetric model with three D3-branes: two IR ones with negative tension located at the ends of an extra-dimensional interval and a UV-brane with positive tension placed in the middle of the interval -- IR-UV-IR model. The background solutions for this geometric setup are found without and with taking into account the backreaction of the matter fields. A 5D $SU(2)$ Higgs doublet is employed as the Goldberger-Wise stabilizing field in this geometry and solutions of the 5D coupled scalar-gravity equations are found by using the superpotential method. Within this setup we investigate the low-energy (zero-mode) effective theory for the bulk Standard Model (SM) bosonic sector. The $\mathbb{Z}_2$-even zero-modes correspond to known standard degrees of freedom, whereas the $\mathbb{Z}_2$-odd zero modes might serve as a dark sector. The effective low-energy scalar sector contains a scalar which mimics the SM Higgs boson and a second stable scalar particle (dark-Higgs) is a dark matter candidate; the latter is a component of the zero-mode of the $\mathbb{Z}_2$-odd Higgs doublet. The model that results from the $\mathbb{Z}_2$-symmetric background geometry resembles the Inert Two Higgs Doublet Model. The effective theory turns out to have an extra residual $SU(2)\times U(1)$ global symmetry that is reminiscent of an underlying 5D gauge transformation for the odd degrees of freedom. At tree level the SM Higgs and the dark-Higgs have the same mass; however, when leading radiative corrections are taken into account the dark-Higgs turns out to be heavier than the SM Higgs. Implications for dark matter are discussed; it is found that the dark-Higgs can provide only a small fraction of the observed dark matter abundance.Comment: 38 pages, 8 figures and 2 tables. v2: a new subsection (2.2) on radius stabilization with an SU(2) bulk Higgs doublet is added, which provides exact analytic background solutions (with full backreaction) of the Higgs-gravity 5D warped setup. References added, matches the version to appear in JHE

Constraints on and future prospects for Two-Higgs-Doublet Models in light of the LHC Higgs signal

We analyze the Two-Higgs-Doublet Models (2HDMs) of Type I and II for consistency with the latest measurements of the ~125.5 GeV Higgs-like signal at the LHC. To this end, we perform scans of the 2HDM parameter space taking into account all relevant pre-LHC constraints as well as the most recent limits coming from searches for heavy Higgs-like states at the LHC. The current status of the 2HDMs of Type I and II is discussed assuming that the observed 125.5 GeV state is one of the two CP-even Higgs bosons, either the lighter h or the heavier H. Implications for future experiments, including expectations regarding other lighter or heavier Higgs bosons are given. The possible importance of heavier Higgs bosons feeding the signals for the 125.5 GeV state is also evaluated.Comment: 52 pages, 32 figures, match to the published versio