0000000001040018
AUTHOR
S. Morisi
Dirac neutrinos from flavor symmetry
We present a model where Majorana neutrino mass terms are forbidden by the flavor symmetry group Delta(27). Neutrinos are Dirac fermions and their masses arise in the same way as that of the charged fermions, due to very small Yukawa couplings. The model fits current neutrino oscillation data and correlates the octant of the atmospheric angle with the magnitude of the lightest neutrino mass, with maximal mixing excluded for any neutrino mass
Neutrino mixing with revamped A(4) flavor symmetry
We suggest a minimal extension of the simplest A(4) flavor model that can induce a nonzero theta(13) value, as required by recent neutrino oscillation data from reactors and accelerators. The predicted correlation between the atmospheric mixing angle theta(23) and the magnitude of theta(13) leads to an allowed region substantially smaller than indicated by neutrino-oscillation global fits. Moreover, the scheme correlates CP violation in neutrino oscillations with the octant of the atmospheric mixing parameter theta(23) in such a way that, for example, maximal mixing necessarily violates CP. We briefly comment on other phenomenological features of the model.
Bilarge neutrino mixing and Abelian flavor symmetry
We explore two bilarge neutrino mixing Anzatze within the context of Abelian flavor symmetry theories: (BL1) sin theta(12) similar to lambda, sin theta(13) similar to lambda, sin theta(23) similar to lambda, and (BL2) sin theta(12) similar to lambda, sin theta(13) similar to lambda, sin theta(23) similar to 1 - lambda. The first pattern is proposed by two of us and is favored if the atmospheric mixing angle theta(23) lies in the first octant, while the second one is preferred for the second octant of theta(23). In order to reproduce the second texture, we find that the flavor symmetry should be U(1) x Z(m), while for the first pattern the flavor symmetry should be extended to U(1) x Z(m) x …
Phenomenology of dark matter from A(4) flavor symmetry
We investigate a model in which Dark Matter is stabilized by means of a Z2 parity that results from the same non-abelian discrete flavor symmetry which accounts for the observed pattern of neutrino mixing. In our A4 example the standard model is extended by three extra Higgs doublets and the Z2 parity emerges as a remnant of the spontaneous breaking of A4 after electroweak symmetry breaking. We perform an analysis of the parameter space of the model consistent with electroweak precision tests, collider searches and perturbativity. We determine the regions compatible with the observed relic dark matter density and we present prospects for detection in direct as well as indirect Dark Matter s…
Absolute neutrino mass scale from flavor symmetries
Abstract The 2012 has been an important year for neutrino physics, current data are reviewed and compared with 2011 global fit. Models based on discrete flavor symmetries predict neutrino mass mass sum-rule (MSR), which is useful to reduce the number of independent model parameters. We found that only four classes of MSR are possible. Such neutrino MSRs constrain the absolute neutrino mass scale. We study the implications of these mass relations for the lightest neutrino mass and for the lower bound of the effective mass m e e of the neutrinoless double beta decay.
Proceedings of the 2nd Workshop on Flavor Symmetries and Consequences in Accelerators and Cosmology (FLASY12)
These are the proceedings of the 2nd Workshop on Flavor Symmetries and Consequences in Accelerators and Cosmology, held 30 June 2012 - 4 July 2012, Dortmund, Germany.
Quark-lepton mass relation in a realistic A(4) extension of the Standard Model
We propose a realistic A(4) extension of the Standard Model involving a particular quark-lepton mass relation, namely that the ratio of the third family mass to the geometric mean of the first and second family masses are equal for down-type quarks and charged leptons. This relation, which is approximately renormalization group invariant, is usually regarded as arising from the Georgi-Jarlskog relations, but in the present model there is no unification group or supersymmetry. In the neutrino sector we propose a simple modification of the so-called Zee-Wolfenstein mass matrix pattern which allows an acceptable reactor angle along with a deviation of the atmospheric and solar angles from thei…
Quark–lepton mass relation in a realistic A4 extension of the Standard Model
AbstractWe propose a realistic A4 extension of the Standard Model involving a particular quark–lepton mass relation, namely that the ratio of the third family mass to the geometric mean of the first and second family masses are equal for down-type quarks and charged leptons. This relation, which is approximately renormalization group invariant, is usually regarded as arising from the Georgi–Jarlskog relations, but in the present model there is no unification group or supersymmetry. In the neutrino sector we propose a simple modification of the so-called Zee–Wolfenstein mass matrix pattern which allows an acceptable reactor angle along with a deviation of the atmospheric and solar angles fro…
Models for neutrino mass with discrete symmetries
Discrete non-abelian flavor symmetries give in a natural way tri-bimaximal (TBM) mixing as showed in a prototype model. However neutrino mass matrix pattern may be very different from the tri-bimaximal one if small deviations of TBM will be observed. We give the result of a model independent analysis for TBM neutrino mass pattern.