A precision constraint on multi-Higgs-doublet models

Journal of Physics G Nuclear and Particle Physics (Impact Factor: 2.84). 12/2007; DOI: 10.1088/0954-3899/35/7/075001
Source: arXiv

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

  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper various constraints for the parameter spaces of two variants of the two-Higgs-doublet model with a Z2-symmetric potential are reconsidered, including the LHC data on existence of a 125 GeV Higgs-like boson. We analyze the model in which only one of the doublets develops a nonzero vacuum expectation value (VEV)—the inert doublet model (IDM) and the mixed model where both of the doublets have nonzero VEVs. Positivity constraints, conditions determining the type of the vacuum, perturbative unitarity condition, constraints following from electroweak precision tests together with the LEP bounds on masses of the scalars are included in the analysis. The analysis is performed without specific assumptions regarding the Yukawa sector. For the IDM constraints on quartic couplings and masses of the scalars as well as their implications for dark matter scenarios are presented. A new type of bound on the mass parameter of the potential coming from the condition for the existence of the inert vacuum is given. In the mixed model a strong bound on the value of tan⁡β, 0.18≲tan⁡β≲5.59, is found. It depends on the mass of the Higgs boson and is independent of the Yukawa interactions. Also standard model (SM)-like scenarios with either h or H playing the role of the SM-like Higgs boson are analyzed.
    Physical review D: Particles and fields 09/2013;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We analyse the constraints and some of the phenomenological implications of a class of two Higgs doublet models where there are flavour-changing neutral currents (FCNC) at tree level but the potentially dangerous FCNC couplings are suppressed by small entries of the CKM matrix $V$. This class of models have the remarkable feature that, as a result of a discrete symmetry of the Lagrangian, the FCNC couplings are entirely fixed in the quark sector by $V$ and the ratio $v_2 /v_1$ of the vevs of the neutral Higgs. The discrete symmetry is extended to the leptonic sector, so that there are FCNC in the leptonic sector with their flavour structure fixed by the leptonic mixing matrix. We analyse a large number of processes, including decays mediated by charged Higgs at tree level, processes involving FCNC at tree level, as well as loop induced processes. We show that in this class of models one has new physical scalars beyond the standard Higgs boson, with masses reachable at the next round of experiments.
    Journal of High Energy Physics 01/2014; 2014(7). · 6.22 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Higgs data analyzed by the ATLAS and CMS Collaborations suggest that the scalar state discovered in 2012 is a Standard Model (SM)--like Higgs boson. Nevertheless, there is still significant room for Higgs physics beyond the Standard Model. Many approaches to electroweak symmetry breaking possess a decoupling limit in which the properties of the lightest CP-even Higgs scalar approach those of the SM Higgs boson. In some cases, an apparent SM-like Higgs signal can also arise in a regime that may not be governed by the decoupling limit. One such scenario can be realized if the observed Higgs signal is a result of two unresolved nearly-mass-degenerate scalar states. The general two-Higgs doublet model provides a useful framework for studying the decoupling limit and possible departures from SM-like Higgs behavior. The implications for current and future Higgs data are briefly considered.


Available from