A precision constraint on multi-Higgs-doublet models

Journal of Physics G Nuclear and Particle Physics (Impact Factor: 5.33). 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.

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    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.
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    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.


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