35 research outputs found
See-saw fermion masses in an SO(10) GUT
In this work we study an SO(10) GUT model with minimum Higgs representations
belonging only to the 210 and 16 dimensional representations of SO(10). We add
a singlet fermion S in addition to the usual 16 dimensional representation
containing quarks and leptons. There are no Higgs bi-doublets and so charged
fermion masses come from one-loop corrections. Consequently all the fermion
masses, Dirac and Majorana, are of the see-saw type. We minimize the Higgs
potential and show how the left-right symmetry is broken in our model where it
is assumed that a D-parity odd Higgs field gets a vacuum expectation value at
the grand unification scale. From the renormalization group equations we infer
that in our model unification happens at 10^{15} GeV and left-right symmetry
can be extended up to some values just above 10^{11} GeV. The Yukawa sector of
our model is completely different from most of the standard grand unified
theories and we explicitly show how the Yukawa sector will look like in the
different phases and briefly comment on the running of the top quark mass. We
end with a brief analysis of lepton number asymmetry generated from the
interactions in our model.Comment: 30 pages, 10 figure
Quark Mass Matrices with Four and Five Texture Zeroes, and the CKM Matrix, in terms of Mass Eigenvalues
Using the triangular matrix techniques of Kuo et al and Chiu et al for the
four and five texture zero cases, with vanishing (11) elements for U and D
matrices, it is shown, from the general eigenvalue equations and hierarchy
conditions, that the quark mass matrices, and the CKM matrix can be expressed
(except for the phases) entirely in terms of quark masses. The matrix
structures are then quite simple and transparent. We confirm their results for
the five texture zero case but find, upon closer examination of all the CKM
elements which our results provide, that six of their nine patterns for the
four texture zero case are not compatible with experiments. In total, only one
five-texture zero and three four-texture zero patterns are allowed.Comment: 15 pages, 3 table
Complex Regge poles in the cut j plane: Pion-nucleon charge-exchange scattering
The structure of the pole-cut combination in πN charge-exchange scattering for t<~0 is represented by a pair of complex poles. Excellent fits to the πN charge-exchange differential cross section, polarization, and total cross-section difference σt(π-p)-σt(π+p) are obtained for the two examples considered, Imα=gsqrt[-t] and Imα=g. The phases of the residues are allowed to vary and a zero in ImA′(-) (the "crossover" zero) is obtained
Neutrino Condensate as Origin of Dark Energy
We propose a new solution to the origin of dark energy. We suggest that it
was created dynamically from the condensate of a singlet neutrino at a late
epoch of the early Universe through its effective self interaction. This
singlet neutrino is also the Dirac partner of one of the three observed
neutrinos, hence dark energy is related to neutrino mass. The onset of this
condensate formation in the early Universe is also related to matter density
and offers an explanation of the coincidence problem of why dark energy (70%)
and total matter (30%) are comparable at the present time. We demonstrate this
idea in a model of neutrino mass with (right-handed) singlet neutrinos and a
singlet scalar.Comment: 5 pages, no figure