153 research outputs found
Non-Minimal Flavored Left-Right Symmetric Model
We propose a non-minimal left-right symmetric model (LRSM) with Parity
Symmetry where the fermion mixings arise as result of imposing an flavor symmetry, and an extra
symmetry is considered to suppress some Yukawa couplings in the lepton sector.
As a consequence, the effective neutrino mass matrix possesses approximately
the symmetry. The breaking of the symmetry induces
sizable non zero , and the deviation of from
is strongly controlled by an free parameter and the
complex neutrino masses. Then, an analytic study on the extreme Majorana phases
is done since these turn out to be relevant to enhance or suppress the reactor
and atmospheric angle. So that we have constrained the parameter space for the
parameter and the lightest neutrino mass that accommodate the mixing
angles. The highlighted results are: a) the normal hierarchy is ruled out since
the reactor angle comes out being tiny, for any values of the Majorana phases;
b) for the inverted hierarchy there is one combination in the extreme phases
where the values of the reactor and atmospheric angles are compatible up to of C. L., but the parameter space is tight; c) the model favors the
degenerate ordering for one combination in the extreme Majorana phases. In this
case, the reactor and atmospheric angle are compatible with the experimental
data for a large set of values of the free parameters. Therefore, this model
may be testable by the future result that the Nova and KamLAND-Zen
collaborations will provide.Comment: Version three. I added references and corrected typos. 19 pages. All
figures replaced, section II changed. Analytic study improved. Conclusions
unchange
B-L Model with Symmetry: Nearest Neighbor Interaction Textures and Broken Symmetry
We make a scalar extension of the B-L gauge model where the
non-abelian discrete group drives mainly the Yukawa sector. Motived by the
large and small hierarchies among the quark and active neutrino masses
respectively, the quark and lepton families are not treated on the same footing
under the assignment of the discrete group. As a consequence, the Nearest
Neighbor Interactions (NNI) textures appear in the quark sector, leading to the
CKM mixing matrix, whereas in the lepton sector, a soft breaking of the symmetry in the effective neutrino mass that comes from
type I see-saw mechanism, provides a non-maximal atmospheric angle and a
non-zero reactor angle.Comment: 20 pages, 6 figures. Improved version and scalar discussion extended
and references added. Version published in EPJ
Flavored Non-Minimal Left-Right Symmetric Model Fermion Masses and Mixings
A complete study on the fermion masses and flavor mixing is presented in a
non-minimal left-right symmetric model (NMLRMS) where the flavor symmetry drives the Yukawa
couplings. In the quark sector, the mass matrices possess a kind of the
generalized Fritzsch textures that allow us to fit the CKM mixing matrix in
good agreement to the last experimental data. In the lepton sector, on the
other hand, a soft breaking of the symmetry provides
a non zero and non maximal reactor and atmospheric angles, respectively. The
inverted and degenerate hierarchy are favored in the model where a set of free
parameters is found to be consistent with the current neutrino data.Comment: 23 pages, 9 figures. references added, typos corrected, JCGI added
his current institution;conclusions rewrote and unchanged results. Version
published in European Physical Journal
Left-right symmetric model with symmetry
We analyze the leptonic sector in the left-right symmetric model dressed with
a discrete symmetry which realizes, after weak spontaneous
breaking, a small broken \mu\lra\tau symmetry that is suggested to explain
observable neutrino oscillation data. \mu\lra\tau symmetry is broken at tree
level in the effective neutrino mass matrix due to the mass difference
in the diagonal Dirac mass
terms, whereas all lepton mixings arise from a Majorana mass matrix. In the
limit of a small breaking we determined , and the deviation from
the maximal value of , in terms of the light neutrino hierarchy
scale, , and a single free parameter of the model.Comment: 9 pages, 4 figures. Title changed and we have added one new section:
CP phase contribution. Minor corrections and references updated. Published
versio
Soft breaking of the symmetry by
The symmetry has been ruled out by its predictions
on the reactor and atmospheric angles, nevertheless, a breaking of this
symmetry might provide correct values. For that reason, we build a
non-renormalizable lepton model where the mixings arise from the spontaneous
breaking of the discrete group,
subsequently the symmetry is broken in the effective
neutrino mass matrix, that comes from the type II see-saw mechanism. As main
result, the reactor and atmospheric angles are corrected and their values are
in good agreement with the experimental data for the inverted hierarchy.
Furthermore, we point out a link between the atmospheric angle and reactor one.
In the quark sector, under certain assumptions, the generalized Fritzsch
textures shape to the quark mass matrices so that the CKM matrix values are
guaranteed.Comment: 19 pages, 6 figures. Minor changes, accepted in Revista Mexicana de
F\'isic
Softly broken symmetry in the minimal see-saw model
Neutrino oscillations data indicates that neutrino mixings are consistent
with an apparent exchange symmetry in neutrino mass
matrix. We observe that in the mininimally extended standard model with the
see-saw mechanism, one can impose symmetry at the tree
level on all Lagrangian terms, but for the mass difference among and
leptons. In the absence of any new extra physics, this mass difference
becomes the only source for the breaking of such a symmetry, which induces, via
radiative corrections, small but predictable values for , and for
the deviation of from maximallity. In the CP conserving case,
the predictions only depend on neutrino mass hierarchy and may provide a unique
way to test for new physics with neutrino experiments.Comment: Typos corrected. References and short discussions added. Final
version, 6 pages, 2 figure
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