49,321 research outputs found
A Highly Predictive Ansatz for Leptonic Mixing and CP Violation
We suggest a simple highly predictive ansatz for charged lepton and light
neutrino mass matrices, based on the assumption of universality of Yukawa
couplings. Using as input the charged lepton masses and light neutrino masses,
the six parameters characterizing the leptonic mixing matrix , are
predicted in terms of a single phase , which takes a value around
. Correlations among variuos physical quantities are
obtained, in particular is predicted as a function of
, and , and
restricted to the range .Comment: 9 pages, 4 figure
Leptonic Invariants, Neutrino Mass-Ordering and the Octant of
We point out that leptonic weak-basis invariants are an important tool for
the study of the properties of lepton flavour models. In particular, we show
that appropriately chosen invariants can give a clear indication of whether a
particular lepton flavour model favours normal or inverted hierarchy for
neutrino masses and what is the octant of . These invariants can
be evaluated in any conveniently chosen weak-basis and can also be expressed in
terms of neutrino masses, charged lepton masses, mixing angles and CP violation
phases.Comment: 10 pages, no figure
Non-Factorizable Phases, Yukawa Textures and the Size of sin (2 beta)
We emphasize the crucial r\^ ole played by non-factorizable phases in the
analysis of the Yukawa flavour structure performed in weak bases with Hermitian
mass matrices and with vanishing entries. We show that non-factorizable
phases are important in order to generate a sufficiently large .
A method is suggested to reconstruct the flavour structure of Yukawa couplings
from input experimental data both in this Hermitian basis and in a
non-Hermitian basis with a maximal number of texture zeros. The corresponding
Froggatt--Nielsen patterns are presented in both cases.Comment: 15 pages, 3 figure
Vortex solutions of the Lifshitz-Chern-Simons theory
We study vortex-like solutions to the Lifshitz-Chern-Simons theory. We find
that such solutions exists and have a logarithmically divergent energy, which
suggests that a Kostelitz-Thouless transition may occur, in which
voxtex-antivortex pairs are created above a critical temperature. Following a
suggestion made by Callan and Wilzcek for the global U(1) scalar field model,
we study vortex solutions of the Lifshitz-Chern-Simons model formulated on the
hyperbolic plane, finding that, as expected, the resulting configurations have
finite energy. For completeness, we also explore Lifshitz-Chern-Simons vortex
solutions on the sphere.Comment: Published version, added appendix on electromagnetic duality in
Lifshitz system
Quasidegeneracy of Majorana Neutrinos and the Origin of Large Leptonic Mixing
We propose that the observed large leptonic mixing may just reflect a
quasidegeneracy of three Majorana neutrinos. The limit of exact degeneracy of
Majorana neutrinos is not trivial, as leptonic mixing and even CP violation may
occur. We conjecture that the smallness of , when compared to the
other elements of , may just reflect the fact that, in the limit of
exact mass degeneracy, the leptonic mixing matrix necessarily has a vanishing
element. We show that the lifting of the mass degeneracy can lead to the
measured value of while at the same time accommodating the observed
solar and atmospheric mixing angles. In the scenario we consider for the
breaking of the mass degeneracy there is only one CP violating phase, already
present in the limit of exact degeneracy, which upon the lifting of the
degeneracy generates both Majorana and Dirac-type CP violation in the leptonic
sector. We analyse some of the correlations among physical observables and
point out that in most of the cases considered, the implied strength of
leptonic Dirac-type CP violation is large enough to be detected in the next
round of experiments.Comment: 16 pages, 4 figures. Matches published version, references added,
improved discussion, results unchange
What if the Masses of the First Two Quark Families are not Generated by the Standard Higgs?
We point out that, in the context of the SM, is
expected to be large, of order one. The fact that motivates the introduction of a symmetry S which
leads to , with only the third generation of
quarks acquiring mass. We consider two scenarios for generating the mass of the
first two quark generations and full quark mixing. One consists of the
introduction of a second Higgs doublet which is neutral under S. The second
scenario consists of assuming New Physics at a high energy scale , contributing
to the masses of light quark generations, in an effective field theory
approach. This last scenario leads to couplings of the Higgs particle to
and which are significantly enhanced with
respect to those of the SM. In both schemes, one has scalar-mediated flavour-
changing neutral currents which are naturally suppressed. Flavour violating top
decays are predicted in the second scenario at the level \mbox{Br} (t
\rightarrow h c ) \geq 5\times 10^{-5}.Comment: 11 pages, 1 figur
Non(anti)commutative superspace with coordinate-dependent deformation
We consider non(anti)commutative superspace with coordinate dependent
deformation parameters . We show that a chiral
supersymmetry can be defined and that chiral and antichiral superfields are
still closed under the Moyal-Weyl associative product implementing the
deformation. A consistent Super Yang-Mills deformed theory can
be constructed provided satisfies a suitable condition which
can be connected with the graviphoton background at the origin of the
deformation. After adding matter we also discuss the Konishi anomaly and the
gluino condensation.Comment: References added. Accepted for publication in PR
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