85 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
An S4 model for quarks and leptons with maximal atmospheric angle
We consider a model for quark and lepton masses and mixings based on S4
flavor symmetry. The model contains six Higgs doublets where three of them give
mass to the leptons and the other three gives mass to the quarks. Charged
fermion and quark masses arise from renormalizable interactions while neutrino
Majorana masses are generated through effective dimension five Weinberg
operator. From the study of the minimization of the scalar potential we found a
residual mu-tau symmetry in the neutrino sector predicting zero reactor angle
and maximal atmospheric angle and for the quark sector we found a four-zero
texture. We give a fit of the mass hierarchies and mixing angles in the quark
sector.Comment: some misprinting corrected, one reference and one commment added,
version to be published on Phys. Rev.
Interpreting IceCube 6-year HESE data as an evidence for hundred TeV decaying Dark Matter
The assumption of a single astrophysical power-law flux to explain the
IceCube 6-year HESE extraterrestrial events yields a large spectral index that
is in tension with gamma-ray observations and the 6-year up-going muon
neutrinos data. Adopting a spectral index belonging to the range
, which is compatible with the one deduced by the
analysis performed on the 6-year up-going muon neutrinos data and with -
astrophysical sources, the latest IceCube data show an up to
excess in the number of events in the energy range 40--200 TeV. We interpret
such an excess as a decaying Dark Matter signal and we perform a
likelihood-ratio statistical test to compare the two-component scenario with
respect to the single-component one.Comment: 7 pages, 4 figures. v2: version published in PL
Fermion masses and mixing in models with SO(10) x A_4 symmetry
We study the flavour sector in models where the three families of matter are
unified in a representation of the group. The
necessary ingredients to realize tri-bi-maximal mixing in the lepton sector are
identified systematically. The non-renormalizable operators contributing to the
fermion mass matrices play an important role. We also present a mechanism to
explain the inter-family mass hierarchy of quarks and charged leptons, which
relies on a `universal seesaw' mechanism and is compatible with tri-bi-maximal
mixing.Comment: 24 pages, revte
The LHC diphoton resonance from gauge symmetry
Motivated by what is possibly the first sign of new physics seen at the LHC,
the diphoton excess at GeV in ATLAS and CMS, we present a model that
provides naturally the necessary ingredients to explain the resonance. The
simplest phenomenological explanation for the diphoton excess requires a new
scalar state, , as well as additional vector-like (VL) fermions
introduced in an ad-hoc way in order to enhance its decays into a pair of
photons and/or increase its production cross-section. We show that the
requiered VL quarks and their couplings can emerge naturally from a complete
framework based on the gauge symmetry.Comment: 8 pages; 2 figures. v2: new references. v3: matches published version
in PR
Probing the Majorana nature of the neutrino with neutrinoless double beta decay
Neutrinoless double beta decay (NDBD) is the only experiment that could probe
the Majorana nature of the neutrino. Here we study the theoretical implications
of NDBD for models yielding tri-bimaximal lepton mixing like A4 and S4.Comment: Talk given at TAUP09, July 1-5, 2009 (Roma).The proceeding will be
published in Journal of Physics, Conference Series (Editors: E. Coccia, L.
Pandola, N. Fornengo, R. Aloisio
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