70 research outputs found
Localization of gauge fields in a tachyonic de Sitter thick braneworld
In this work we show that universal gauge vector fields can be localized on
the recently proposed 5D thick tachyonic braneworld which involves a de Sitter
cosmological background induced on the 3-brane. Namely, by performing a
suitable decomposition of the vector field, the resulting 4D effective action
corresponds to a massive gauge field, while the profile along the extra
dimension obeys a Schroedinger-like equation with a Poeschl-Teller potential.
It turns out that the massless zero mode of the gauge field is bound to the
expanding 3-brane and allows us to recover the standard 4D electromagnetic
phenomena of our world. Moreover, this zero mode is separated from the
continuum of Kaluza-Klein (KK) modes by a mass gap determined by the scale of
the expansion parameter. We also were able to analytically solve the
corresponding Schroedinger-like equation for arbitrary mass, showing that KK
massive modes asymptotically behave like plane waves as expected.Comment: 7 pages in latex, no figure
Warped flavor symmetry predictions for neutrino physics
A realistic five-dimensional warped scenario with all standard model fields
propagating in the bulk is proposed. Mass hierarchies would in principle be
accounted for by judicious choices of the bulk mass parameters, while fermion
mixing angles are restricted by a flavor symmetry broken on the
branes by flavon fields. The latter gives stringent predictions for the
neutrino mixing parameters, and the Dirac CP violation phase, all described in
terms of only two independent parameters at leading order. The scheme also
gives an adequate CKM fit and should be testable within upcoming oscillation
experiments.Comment: 19 pages, 2 figue
A new neutrino mass sum rule from inverse seesaw
A class of discrete flavor-symmetry-based models predicts constrained
neutrino mass matrix schemes that lead to specific neutrino mass sum-rules
(MSR). One of these implies in a lower bound on the effective neutrinoless
double beta mass parameter, even for normal hierarchy neutrinos. Here we
propose a new model based on the S4 flavor symmetry that leads to the new
neutrino mass sum-rule and discuss how to generate a nonzero value for the
reactor mixing angle indicated by recent experiments, and the resulting
correlation with the solar mixing angle.Comment: 14 pages, 4 figure
Neutrino masses generation in a Z_4 model
We present a renormalizable flavor model with Z_4 as flavor symmetry in both
the quark and lepton sectors. The model is constructed with a minimal approach
and no-right handed neutrinos are introduced. In this approach a minimum number
of two SU(2) Higgs doublets and one scalar singlet are required in order to
obtain the Nearest Neighbor Interaction form for charged fermions and to
generate neutrino masses radiatively. For the quark sector we follow the charge
assignations made by Branco et. al. in reference [1]. All fermion masses and
mixing angles in the model are in agreement with current experimental data and
only the inverted hierarchy for the neutrino mass spectrum is allowed. Since
neutrinos are Majorana the contribution to neutrinoless double beta decay is
also analyzed.Comment: v1:24 pages, 4 figures,v2: references added,v3:25 pages, 4 figures,
corrections and improvements have been made, all data and figures have been
updated and typos fixe
Z_4 flavor model in Randall-Sundrum model 1
Randall Sundrum models provide a possible explanation of (gauge-gravity)
hierarchy, whereas discrete symmetry flavor groups yield a possible description
of the texture of Standard Model fermion masses. We use both these ingredients
to propose a five-dimensional extension of the Standard Model where the mass
hierarchy of the four-dimensional effective field theory is obtained only using
localizations parameters of order 1. We consider a bulk custodial gauge
symmetry group together with an Abelian group: the model turns out to
yield a rather minimal extension of the SM as it only requires two brane Higgs
fields to provide the desired Yukawa interactions and the required spontaneous
symmetry breaking pattern. In fact, the presence of an extra-dimension allows
the use of the Scherk-Schwarz mechanism to contribute to the breaking of the
bulk custodial group down to the SM gauge symmetry. Moreover, no right-handed
neutrinos are present and neutrino masses are generated radiatively with the
help of a bulk charged scalar field that provides the Lepton-number violation.
Using experimental inputs from the Global Neutrino Analysis and recent Daya Bay
results, a numerical analysis is performed and allowed parameter regions are
displayed.Comment: 23 pages, 3 figures. A brief discussion on contribution from higher
order operators has been added, a few typos corrected and references added.
Version to appear in Phys. Rev.
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