We derive a general expression for Δρ (or, equivalently, the oblique parameter T) in SU(2) × U(1) electroweak model with an arbitrary number of scalar doublets, hypercharge ±1/2, and singlets. The experimental bound on constitutes strong constraint masses mixings particles that model.

We confront the two-Higgs-doublet model with a variety of experimental constraints as well theoretical consistency conditions. The most constraining data are $\overline{B}\ensuremath{\rightarrow}{X}_{s}\ensuremath{\gamma}$ decay rate (at low values ${M}_{{H}^{\ifmmode\pm\else\textpm\fi{}}}$), and $\ensuremath{\Delta}\ensuremath{\rho}$ both high ${M}_{{H}^{\ifmmode\pm\else\textpm\fi{}}}$). also take into account $B\overline{B}$ oscillation ${R}_{b}$, or width...

We explore an extension of the inert doublet model which allows also for $CP$ violation in Higgs sector. This necessitates two noninert doublets. The lightest neutral scalar is a candidate dark matter. Scanning over parameters we preserve abundance matter agreement with WMAP data. impose all relevant collider and theoretical constraints to determine allowed parameter space both appropriate violated. In addition find regions where cutoff originating from naturality arguments can be...

Abstract The Two Higgs Doublet Model invariant under the gauge group $$SU(2)\times U(1)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>S</mml:mi> <mml:mi>U</mml:mi> <mml:mo>(</mml:mo> <mml:mn>2</mml:mn> <mml:mo>)</mml:mo> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:math> is known to have six additional global discrete or continuous symmetries of its scalar sector. We discovered regions parameter space model which are basis and renormalization all...

We present a detailed study of the vacua $S_3$-symmetric three-Higgs-doublet potential, specifying region parameters where these minimisation solutions occur. work with CP conserving scalar potential and analyse possible real complex emphasis on cases in which symmetry can be spontaneously broken. Results are presented both reducible-representation framework Derman, irreducible-representation framework. Mappings between given. Some implementations principle accommodate dark matter for that...

For the general two-Higgs-doublet model, we present conditions for having spontaneous $CP$ violation, in terms of physical masses and couplings. These relations involve charged Higgs mass, its cubic couplings with neutral scalars quartic coupling, become particularly simple alignment limit. In simplified model softly broken ${\mathcal{Z}}_{2}$ symmetry, some deviation from is required violation to be present.

Models with two or more scalar doublets discrete global symmetries can have vacua vanishing vacuum expectation values in the bases where are imposed. If a suitable symmetry stabilises such vacua, these models may lead to interesting dark matter candidates, provided that prevents couplings among candidates and fermions. We analyse three-Higgs-doublet an underlying $S_3$ symmetry. These many distinct one which be stabilised by remnant of survived spontaneous breaking. discuss all possible...

In Two-Higgs-Doublet models, the conditions for CP violation can be expressed in terms of invariants under U(2) rotations among two SU(2) Higgs doublet fields. order to design a strategy measuring we express them observables, i.e., masses and couplings scalar bosons. We find amplitudes directly sensitive invariants. Observation Standard-Model-like boson at LHC severely constrains models. particular, model with $$ {\mathbb{Z}}_2 symmetry imposed on dimension-4 (in eliminate tree-level...

A bstract The Standard Model (SM)-like couplings of the observed Higgs boson impose strong constraints on structure any extended sector. We consider theoretical properties and phenomenological implications a generic two doublet model (2HDM). This constitutes simple attractive extension SM that is consistent with observation SM-like precision electroweak observables, while providing potential new source CP-violation. In this paper we focus so-called alignment limit 2HDM, where neutral scalar...

We discuss possibilities of measuring CP violation in the Two-Higgs-Doublet Model by studying effects one-loop generated ZZZ and ZW W vertices. a set CP-sensitive asymmetries for ZZ + − production at linear e −-colliders, that directly depends on weak-basis invariant Im J 2 parametrises strength violation. Given restrictions this model follow from LHC measurements, predicted are small. Pursuing such measurements is however very important, as an observed signal might point to richer scalar sector.

We have explored properties of an extension the Inert Doublet Model by addition extra non-inert scalar doublet. The model offers a possibility CP violation in sector and candidate for Dark Matter. Allowed regions plane spanned mass Dark-Matter particle lightest neutral Higgs been identified, constraints from direct indirect-detection experiments studied. For favorable parameter one may observe long-lived charged particles produced at LHC.

A bstract We explore some aspects of models with two and three SU(2) scalar doublets that lead to mass degeneracies among the physical scalars. In Higgs sectors doublets, exact degeneracy masses, without an artificial fine-tuning potential parameters, is possible only in case inert doublet model (IDM), where respects a global U(1) symmetry not broken by vacuum. we introduce analyze replicated model, which possesses then generalize this obtain potential, first proposed Ivanov Silva, CP4...

In this paper we analyze in detail an ${S}_{3}$-symmetric three-Higgs-doublet model with a specific vacuum configuration. This analysis allows us to illustrate important features of models several Higgs doublets, such as the possibility having spontaneous $CP$ violation. We start real potential and pick particularly interesting complex configuration, which does not violate before adding soft breaking terms potential. study role played by different symmetry terms. These are essential for our...

A bstract CP violation plays a very important role in nature with implications both for Particle Physics and Cosmology. Accounting the observed matter-antimatter asymmetry of Universe requires existence new sources beyond Standard Model. In models an extended scalar sector can emerge either explicitly, i.e., at Lagrangian level, or spontaneously. Spontaneous occurs framework electroweak symmetry breaking whenever conserves vacuum breaks it. This that not all expectation values be real....

The Two-Higgs-Doublet Model is considered, in its CP-non-conserving version. It shown quantitatively how vacuum stability and tree-level unitarity the Higgs-Higgs-scattering sector constrain parameter space of model. In particular, at high values tanbeta, model violates unitarity, unless some Higgs bosons are heavy. regime large CP violation neutral-Higgs-t-quark sector, which requires tanbeta lsim 1, Yukawa coupling (determined by neutral-Higgs-sector rotation matrix) reasonably...

We have investigated a Two-Higgs-Doublet Model (2HDM), focusing on CP violation. Various scenarios with spontaneous and explicit breaking of been considered. Some features violation related to choice the basis for two Higgs doublets discussed clarified. Regions in physical parameter space corresponding located discussed. The possibility determine parameters scalar potential no reference Yukawa couplings has considered an unavoidable ambiguity found. issue disentangling investigated.

Models with an extended scalar electroweak sector are well motivated. Such models could accommodate a dark matter candidate if there is additional representation vanishing vacuum expectation value and, in addition, no couplings between fermions and the candidate. The most natural way to have these conditions implemented consider where underlying symmetry imposed. Governed by this, we three-Higgs-doublet model $S_3$ symmetry. Within this framework different implementations which possibly...

A bstract Symmetries of the Two-Higgs-Doublet Model (2HDM) potential that can be extended to whole Lagrangian, i.e. CP-symmetries CP1, CP2, CP3 and Higgs-family symmetries Z 2 , U(1) SO(3) are discussed. Sufficient necessary conditions in terms constraints on masses physical couplings for respect each these found. Each symmetry realized through several alternative cases, case being a set relations among parameters. We will show some those invariant under renormalization group, but others...

Soft breaking of a symmetry requires an invariance the dimension-4 part Lagrangian and non-trivial variation lower-dimensional part. However, in general, separation between dim-4 is not invariant with respect to basis transformations fields. Therefore, natural question physical meaning soft arises. This problem addressed here framework two-Higgs-Doublet Models (2HDM). It has been shown, within these models, that spite ambiguity corresponding lower-dimension Lagrangian, implications could be...

For models with several Higgs doublets we present an alternative method to the one proposed by Branco, Gerard and Grimus, in 1984, check whether or not CP is spontaneously violated potential. The previous powerful rigorous. It requires identification of a matrix U corresponding symmetry Lagrangian verifying simple relation involving vacuum expectation values. nonexistence such signals spontaneous violation. This approach may be far from trivial as complexity grows number doublets. In cases...

We discuss the importance of basis invariants in general 2HDM and how these relates to masses couplings. also present a simple, yet powerful technique translate parameters potential into combinations couplings theory apply this CP odd invariants.