1,518 research outputs found
Neutrino, Lepton, and Quark Masses in Supersymmetry
The recently proposed model of neutrino mass with no new physics beyond the
TeV energy scale is shown to admit a natural and realistic supersymmetric
realization, when combined with another recently proposed model of quark masses
in the context of a softly broken U(1) symmetry. Four Higgs doublets are
required, but two must have masses at the TeV scale. New characteristic
experimental predictions of this synthesis are discussed.Comment: 7 pages, no figur
The U(1) symmetry of the non-tribimaximal pattern in the degenerate mass spectrum case of the neutrino mass matrix
On account of the new neutrino oscillation data signalling a non-zero value
for the smallest mixing angle (), we present an explicit realization
of the underlying U(1) symmetry characterizing the maximal atmospheric mixing
angle () pattern with two degenerate masses but now with
generic values of . We study the effects of the form invariance with
respect to U(1), and/or , subgroups, on the Yukawa couplings and the
mass terms. Later on, we specify to its experimental best fit value
(), and impose the symmetry in an entire model which includes
charged leptons, and many Higgs doublets or standard model singlet heavy
scalars, to show that it can make room for the charged lepton mass hierarchies.
In addition, we show for the non-tribimaximal value of within
type-I seesaw mechanism enhanced with flavor symmetry that neutrino mass
hierarchies can be generated. Furthermore, lepton/baryogenesis can be
interpreted via type-II seesaw mechanism within a setup meeting the flavor
U(1)-symmetry.Comment: latex, 1 table, 20 pages. Typos are corrected, shortened version to
appear in Phys. Rev.
On Myosin II dynamics in the presence of external loads
We address the controversial hot question concerning the validity of the
loose coupling versus the lever-arm theories in the actomyosin dynamics by
re-interpreting and extending the phenomenological washboard potential model
proposed by some of us in a previous paper. In this new model a Brownian motion
harnessing thermal energy is assumed to co-exist with the deterministic swing
of the lever-arm, to yield an excellent fit of the set of data obtained by some
of us on the sliding of Myosin II heads on immobilized actin filaments under
various load conditions. Our theoretical arguments are complemented by accurate
numerical simulations, and the robustness of the model is tested via different
choices of parameters and potential profiles.Comment: 6 figures, 8 tables, to appear on Biosystem
Resonant Leptogenesis and Verifiable Seesaw from Large Extra Dimensions
In the presence of large extra dimensions, the fundamental scale could be as
low as a few TeV. This yields leptogenesis and seesaw at a TeV scale.
Phenomenologically two TeV-scale Majorana fermions with a small mass split can
realize a resonant leptogenesis whereas a TeV-scale Higgs triplet with a small
trilinear coupling to the standard model Higgs doublet can give a verifiable
seesaw. We propose an interesting scenario where the small parameters for the
resonant leptogenesis and the type-II seesaw can be simultaneously generated by
the propagation of lepton number violation from distant branes to our world.Comment: 5 pages. More discussions and references. Published in PR
Duality in Left-Right Symmetric Seesaw Mechanism
We consider type I+II seesaw mechanism, where the exchanges of both
right-handed neutrinos and isotriplet Higgs bosons contribute to the neutrino
mass. Working in the left-right symmetric framework and assuming the mass
matrix of light neutrinos and the Dirac-type Yukawa couplings to be
known, we find the triplet Yukawa coupling matrix , which carries the
information about the masses and mixing of the right-handed neutrinos. We show
that in this case there exists a duality: for any solution , there is a dual
solution , where is the VEV of the triplet Higgs.
Thus, unlike in pure type I (II) seesaw, there is no unique allowed structure
for the matrix . For lepton generations the number of solutions is
. We develop an exact analytic method of solving the seesaw non-linear
matrix equation for .Comment: 4 pages, revtex, small clarifications added, title changed to match
published versio
Neutrino mixing matrix in the 3-3-1 model with heavy leptons and symmetry
We study the lepton sector in the model based on the local gauge group
which do not contain particles with
exotic electric charges. The seesaw mechanism and discrete symmetry are
introduced into the model to understand why neutrinos are especially light and
the observed pattern of neutrino mixing. The model provides a method for
obtaining the tri-bimaximal mixing matrix in the leading order. A non-zero
mixing angle presents in the modified mixing matrix.Comment: 10 page
The small mixing angle and the lepton asymmetry
We present the correlation of low energy CP phases, both Dirac and Majorana,
and the lepton asymmetry for the baryon asymmetry in the universe, with a
certain class of Yukawa matrices that consist of two right-handed neutrinos and
include one texture zero in themselves. For cases in which the amount of the
lepton asymmetry turns out to be proportional to , we
consider the relation between two types of CP phases and the relation of
versus the Jarlskog invariant or the amplitude of neutrinoless double beta
decay as varies.Comment: 17 pages, 14 figures, information for figures added, version
published in PR
Gauge mediated supersymmetry breaking and the cosmology of Left-Right symmetric model
Left-Right symmetry including supersymmetry presents an important class of
gauge models which may possess natural solutions to many issues of
phenomenology. Cosmology of such models indicates a phase transition
accompanied by domain walls. Such walls must be unstable in order to not
conflict with standard cosmology, and can further be shown to assist with open
issues of cosmology such as dilution of unwanted relic densities and
leptogenesis. In this paper we construct a model of gauge mediated
supersymmetry breaking in which parity breaking is also signalled along with
supersymmetry breaking and so as to be consistent with cosmological
requirements. It is shown that addressing all the stated cosmological issues
requires an extent of fine tuning, while in the absence of fine tuning,
leptogenesis accompanying successful completion of the phase transition is
still viable
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