115 research outputs found
The flavor physics in unified gauge theory from an S_3*P discrete symmetry
We investigate the phenomenological implication of the discrete symmetry
S_3*P on flavor physics in SO(10) unified theory. We construct a minimal
renormalizable model which reproduces all the masses and mixing angle of both
quarks and leptons. As usually the SO(10) symmetry gives up to relations
between the down sector and the charged lepton masses. The underlining discrete
symmetry gives a contribution (from the charged lepton sector) to the PMNS
mixing matrix which is bimaximal. This gives a strong correlation between the
down quark and charged lepton masses, and the lepton mixing angles. We obtain
that the small entries V_{ub}, V_{cb}, V_{td}, and V_{ts} in the CKM matrix are
related to the small value of the ratio "dm^2_{sol}/dm^2_{atm}": they come from
both the S_2*P structure of our model and the small ratio of the other quark
masses with respect to m_t.Comment: 5 pages, revtex4. v2: published versio
Predictions for "mu -> e gamma" in SUSY from non trivial Quark-Lepton complementarity
We compute the effect of non diagonal neutrino mass in l_i -> l_j gamma in
SUSY theories with non trivial Quark-Lepton complementarity and a flavor
symmetry. The correlation matrix V_M=U_{CKM}U_{PMNS} is such that its (1,3)
entry, as preferred by the present experimental data, is zero. We do not assume
that is bimaximal.
Quark-Lepton complementarity and the flavor symmetry strongly constrain the
theory and we obtain a clear prediction for the contribution to mu -> e gamma
and the tau decays tau -> e gamma and tau -> mu gamma. If the Dirac neutrino
Yukawa couplings are degenerate but the low energy neutrino masses are not
degenerate, then the lepton decays are related among them by the V_M entries.
On the other hand, if the Dirac neutrino Yukawa couplings are hierarchical or
the low energy neutrino masses are degenerate, then the prediction for the
lepton decays comes from the U_{CKM} hierarchy.Comment: 19 pages; V2 Version to appear in Advances in High Energy Physic
Neutrino Mass Matrices with Vanishing Determinant and
We investigate the prospects for scenarios with vanishing determinant
neutrino mass matrices and vanishing mixing angle. Normal and
inverse mass hierarchies are considered separately. For normal hierarchy it is
found that neutrinoless double beta decay cannot be observed by any of the
present or next generation experiments. For inverse hierarchy the neutrinoless
double beta decay is, on the contrary, accessible to experiments. We also
analyse for both hierarchies the case for texture zeros and equalities between
mass matrix elements. No texture zeros are found to be possible nor any such
equalities, apart from the obvious ones.Comment: 14 pages, 1 figur
Neutrino masses and tribimaximal mixing in the minimal renormalizable supersymmetric SU(5) grand unified model with A4 flavor symmetry
We analyze all possible extensions of the recently proposed minimal
renormalizable SUSY SU(5) grand unified model with the inclusion of an
additional A4 flavor symmetry. We find that there are five possible cases but
only one of them is phenomenologically interesting. We develop in detail such
case and we show how the fermion masses and mixing angles come out. As a
prediction we obtain the neutrino masses of order of 0.1 eV with an inverted
hierarchy.Comment: V1: 22 pages, V2: 16 pages, published version, results unchange
Highest states in light-cone superstring
We study the highest states in the compact rank-1 sectors of the AdS5 X S5
superstring in the framework of the recently proposed light cone Bethe Ansatz
equations. In the su(1|1) sector we present strong coupling expansions in the
two limits L,lambda -> OO (expanding in power of lambda^{-1/4} with fixed large
L) and lambda, L -> OO (expanding in power of 1/L with fixed large lambda)
where lambda is the 't Hooft coupling and L is the number of Bethe momenta. The
two limits do not commute apart from the leading term which reproduces the
result obtained with the Arutyunov-Frolov-Staudacher phase in the lambda, L ->
OO limit. In the su(2) sector we perform the strong coupling expansions in the
L->OO limit up to O(lambda^{-1/4}), and our result is in agreement with
previuos String Bethe Ansatz analysis.Comment: 33 pages, 3 eps figure
A model for fermion masses and lepton mixing in SO(10) x A4
The discrete flavor symmetry A4 explains very well neutrino data at low
energy, but it seems difficult to extend it to grand unified models since in
general left-handed and right-handed fields belong to different A4
representations. Recently it has been proposed a model where all the fermions
equally transform under A4. We study here a concrete SO(10) realization of such
a model providing small neutrino masses through the seesaw mechanism. We fit at
tree level the charged fermion masses run up to the unification scale. Some
fermion masses properties come from the SO(10) symmetry while lepton mixing
angles are consequence of the A4 properties. Moreover, our model predicts the
absolute value of the neutrino masses, these ones are in the range .Comment: 15 pages. V2: Final version to appear in the journa
Gallium data variability and KamLAND
We present an alternative fit to the conventional solar+KamLAND one which
takes into account the possible time dependence of the Ga data and relies on
the partial conversion of active sterile neutrinos via the magnetic
moment/solar field interaction. We evaluate the prediction for the solar
neutrino rates obtaining a fit of similar quality as the LMA one. We also
evaluate the KamLAND antineutrino survival probability as a function of reactor
distance and find a better agreement with data as compared to LMA.Comment: 3 pages, 1 figure, presented at NOW2006, Sep.9-16, Otranto, Ital
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