1,615 research outputs found
CP4 miracle: shaping Yukawa sector with CP symmetry of order four
We explore the phenomenology of a unique three-Higgs-doublet model based on
the single CP symmetry of order 4 (CP4) without any accidental symmetries. The
CP4 symmetry is imposed on the scalar potential and Yukawa interactions,
strongly shaping both sectors of the model and leading to a very characteristic
phenomenology. The scalar sector is analyzed in detail, and in the Yukawa
sector we list all possible CP4-symmetric structures which do not run into
immediate conflict with experiment, namely, do not lead to massless or
mass-degenerate quarks nor to insufficient mixing or CP-violation in the CKM
matrix. We show that the parameter space of the model, although very
constrained by CP4, is large enough to comply with the electroweak precision
data and the LHC results for the 125 GeV Higgs boson phenomenology, as well as
to perfectly reproduce all fermion masses, mixing, and CP violation. Despite
the presence of flavor changing neutral currents mediated by heavy Higgs
scalars, we find through a parameter space scan many points which accurately
reproduce the kaon CP-violating parameter as well as oscillation
parameters in K and mesons. Thus, CP4 offers a novel minimalistic
framework for building models with very few assumptions, sufficient predictive
power, and rich phenomenology yet to be explored.Comment: 39 pages, 8 figures, 1 table; v2: expanded discussion, extra
references, matches published versio
Dark matter from CP symmetry of order 4: evolution in the asymmetric regime
Multi-Higgs models equipped with global symmetries produce scalar dark matter
(DM) candidates stabilized by the unbroken symmetry. It is remarkable that a
conserved CP symmetry can also stabilize DM candidates, provided it is a CP
symmetry of order higher than two. CP4 3HDM, the three-Higgs-doublet model with
CP symmetry of order 4, is the simplest example of this kind. It contains two
mass-degenerate scalar DM candidates and , each of them
being a CP4 eigenstate and, therefore, its own antiparticle. A novel
phenomenological feature of this model is the presence of conversion process, which conserves CP.
It offers a rare example of DM models in which self-interaction in the dark
sector can significantly affect cosmological and astrophysical observables.
Here, we explore the thermal evolution of these DM species in the asymmetric
regime. We assume that a mechanism external to CP4 3HDM produces an initial
imbalance of the densities of and . As the Universe
cools down, we track the evolution of the asymmetry through different stages,
and determine how the final asymmetry depends on the interplay between the
conversion and annihilation SM and on the initial
conditions. We begin with the analytic treatment of Boltzmann equations,
present a detailed qualitative description of the process, and then corroborate
it with numerical results obtained using a dedicated computer code. Finally, we
check if the model can produce an observable indirect detection signal.Comment: 17 pages, 4 figure
Symmetries for the 4HDM: extensions of cyclic groups
Multi-Higgs models equipped with global symmetry groups, either exact or
softly broken, offer a rich framework for constructions beyond the Standard
Model and lead to remarkable phenomenological consequences. Knowing all the
symmetry options within each class of models can guide its phenomenological
exploration, as confirmed by the vast literature on the two- and
three-Higgs-doublet models. Here, we begin a systematic study of finite
non-abelian symmetry groups which can be imposed on the scalar sector of the
four-Higgs-doublet model (4HDM) without leading to accidental symmetries. In
this work, we derive the full list of such non-abelian groups available in the
4HDM that can be constructed as extensions of cyclic groups by their
automorphism groups. This list is remarkably restricted but it contains cases
which have not been previously studied. Since the methods we develop may prove
useful for other classes of models, we present them in a pedagogical manner.Comment: v2: 36 pages, 2 tables, additional clarifications, matches the
published versio
Frustrated symmetries in multi-Higgs-doublet models
Within multi-Higgs-doublet models, one can impose symmetries on the Higgs
potential, either discrete or continuous, that mix several doublets. In
two-Higgs-doublet model any such symmetry can be conserved or spontaneously
violated after the electroweak symmetry breaking (EWSB), depending on the
coefficients of the potential. With more than two doublets, there exist
symmetries which are always spontaneously violated after EWSB. We discuss the
origin of this phenomenon and show its similarity to geometric frustration in
condensed-matter physics.Comment: 7 pages, no figure
Exclusive quasielastic production of dijets at hadronic colliders
We critically re-examine the calculation of central production of dijets in
quasi-elastic hadronic collisions. We find that the process is not dominated by
the perturbative contribution, and discuss several sources of uncertainties in
the calculation.Comment: 4 pages, talk given at Diffraction-2008, La Londe-les-Maures, France,
9-14 Sept 200
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