1,977 research outputs found
Quark Mixings in and Suppression of
The quark mixing matrix is studied in depth on the basis of
superstring inspired model with global flavor symmetries.
The sizable mixings between right-handed down-type quark and colored
Higgs field potentially occur but no such mixings in up-type quark
sector. In the model the hierarchical pattern of is understood
systematically. It is shown that due to large - mixings is
naturally suppressed compared to . It is pointed out that the observed
suppression of is in favor of the presence of gauge symmetry
but not in accord with generic SU(5) GUT.Comment: 10pages with no figure, Latex fil
Towards a Simulation of Quantum Computers by Classical Systems
We present a two-dimensional classical stochastic differential equation for a
displacement field of a point particle in two dimensions and show that its
components define real and imaginary parts of a complex field satisfying the
Schroedinger equation of a harmonic oscillator. In this way we derive the
discrete oscillator spectrum from classical dynamics. The model is then
generalized to an arbitrary potential. This opens up the possibility of
efficiently simulating quantum computers with the help of classical systems.Comment: Author Information under
http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of
paper (including all PS fonts) at
http://www.physik.fu-berlin.de/~kleinert/kleiner_re324/preprint.htm
Fermion Masses and Mixings in a String Inspired Model
In the context of Calabi-Yau string models we explore the origin of
characteristic pattern of quark-lepton masses and the CKM matrix. The discrete
-symmetry is introduced and the is assigned to the
-parity. The gauge symmetry at the string scale, , is
broken into the standard model gauge group at a very large intermediate energy
scale. At energies below the intermediate scale down-type quarks and also
leptons are mixed with unobserved heavy states, respectively. On the other
hand, there are no such mixings for up-type quarks. Due to the large mixings
between light states and heavy ones we can derive phenomenologically viable
fermion mass hierarchies and the CKM matrix. Mass spectra for
intermediate-scale matter beyond the MSSM are also determined. Within this
framework proton lifetime is long enough to be consistent with experimental
data. As for the string scale unification of gauge couplings, however,
consistent solutions are not yet found.Comment: 49 pages, 1 figure, Latex Revised version includes discussion on FCNC
problems. Final version to appear in Prog. Theor. Phys. Vol.96 No.
Thermal leptogenesis in a supersymmetric neutrinophilic Higgs model
We investigate thermal leptogenesis in a supersymmetric neutrinophilic Higgs
model by taking phenomenological constraints into account, where, in addition
to the minimal supersymmetric standard model, we introduce an extra Higgs field
with a tiny vacuum expectation value (VEV) which generates neutrino masses.
Thanks to this tiny VEV of the neutrinophilic Higgs, our model allows to reduce
the mass of the lightest right-handed (s)neutrino to be GeV as
keeping sufficiently large CP asymmetry in its decay. Therefore, the reheating
temperature after inflation is not necessarily high, hence this scenario is
free from gravitino problem.Comment: 5 pages, 1 figur
A Supersymmetric Contribution to the Neutrino Mass Matrix and Breaking of mu-tau Symmetry
Supersymmetry broken by anomaly mediation suffers from tachyonic slepton
masses. A possible solution to this problem results in "decoupling", i.e., the
first two generations of sfermions are much heavier than the third one. We note
that in this scenario a sizable loop-induced contribution to the neutrino mass
matrix results. As an application of this scenario we take advantage of the
fact that the decoupling evidently not obeys 2-3 generation exchange symmetry.
In the neutrino sector, this 2-3 symmetry (or mu-tau symmetry) is a useful
Ansatz to generate zero theta_{13} and maximal theta_{23}. The induced
deviations from these values are given for some examples, thereby linking SUSY
breaking to the small parameters (including possibly the solar mass splitting)
of the neutrino sector.Comment: 5 pages, 1 figur
How Can We Obtain a Large Majorana-Mass in Calabi-Yau Models ?
In a certain type of Calabi-Yau superstring models it is clarified that the
symmetry breaking occurs by stages at two large intermediate energy scales and
that two large intermediate scales induce large Majorana-masses of right-handed
neutrinos. Peculiar structure of the effective nonrenormalizable interactions
is crucial in the models. In this scheme Majorana-masses possibly amount to
O(10^{9 \sim 10}\gev) and see-saw mechanism is at work for neutrinos. Based
on this scheme we propose a viable model which explains the smallness of masses
for three kind of neutrinos .
Special forms of the nonrenormalizable interactions can be understood as a
consequence of an appropriate discrete symmetry of the compactified manifold.Comment: 30-pages + 6-figures, LaTeX, Preprint DPNU-94-02, AUE-01-9
5D seesaw, flavor structure, and mass textures
In the 5D theory in which only 3 generation right-handed neutrinos are in the
bulk, the neutrino flavor mixings and the mass spectrum can be constructed
through the seesaw mechanism. The 5D seesaw is easily calculated just by a
replacement of the
Majorana mass eigenvalues, M_i, by 2 M_*tan(h)[\pi RM_i] (M_*: 5D Planck
scale,
R: compactification radius). The 5D features appear when the bulk mass, which
induces the 4D Majorana mass, is the same as the compactification scale or
larger than it. Depending on the type of bulk mass, the seesaw scales of the 3
generations are strongly split (the tan-function case) or degenerate (the
tanh-function case). In the split case, the seesaw enhancement is naturally
realized. The single right-handed neutrino dominance works in a simple setup,
and some specific mass textures, which are just assumptions in the 4D setup,
can be naturally obtained in
5 dimensions. The degenerate case is also useful for a suitable neutrino
flavor structure.Comment: 15 page
Fermion Mass Hierarchy in 6 dimensional SO(10) SUSY GUT
We suggest simple models which produce the suitable fermion mass hierarchies
and flavor mixing angles based on the supersymmetric SO(10) grand unified
theory in 6 dimensions compactified on a T^2/Z_2 orbifold. The gauge and Higgs
fields propagate in 6 dimensions while ordinal chiral matter fields are
localized in 4 dimensions. We introduce extra vector-like heavy fields in the
extra dimensions. We show three models according to the configurations of
vector-like fields in extra dimensions. The suitable fermion mass hierarchies
and flavor mixings are generated by integrating out these vector-like heavy
fields.Comment: 14page
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