23,470 research outputs found
On the four-zero texture of quark mass matrices and its stability
We carry out a new study of quark mass matrices (up-type) and
(down-type) which are Hermitian and have four zero entries, and
find a new part of the parameter space which was missed in the previous works.
We identify two more specific four-zero patterns of and
with fewer free parameters, and present two toy flavor-symmetry
models which can help realize such special and interesting quark flavor
structures. We also show that the texture zeros of and
are essentially stable against the evolution of energy scales in
an analytical way by using the one-loop renormalization-group equations.Comment: 33 pages, 4 figures, minor comments added, version to appear in Nucl.
Phys.
Constraining f(R) gravity in solar system, cosmology and binary pulsar systems
The gravity can be cast into the form of a scalar-tensor theory, and
scalar degree of freedom can be suppressed in high-density regions by the
chameleon mechanism. In this article, for the general gravity, using a
scalar-tensor representation with the chameleon mechanism, we calculate the
parameterized post-Newtonian parameters and , the effective
gravitational constant , and the effective cosmological constant
. In addition, for the general gravity, we also
calculate the rate of orbital period decay of the binary system due to
gravitational radiation. Then we apply these results to specific models
(Hu-Sawicki model, Tsujikawa model and Starobinsky model) and derive the
constraints on the model parameters by combining the observations in solar
system, cosmological scales and the binary systems.Comment: LaTex, 19 pages,1 figure, typo corrected. To appear in Physics
Letters
The effective neutrino mass of neutrinoless double-beta decays: how possible to fall into a well
If massive neutrinos are the Majorana particles and have a normal mass
ordering, the effective mass term of a neutrinoless
double-beta () decay may suffer significant cancellations among
its three components and thus sink into a decline, resulting in a "well" in the
three-dimensional graph of against the smallest
neutrino mass and the relevant Majorana phase . We present a new
and complete analytical understanding of the fine issues inside such a well,
and discover a novel threshold of in terms of the
neutrino masses and flavor mixing angles: in connection with and . This threshold point, which links the
{\it local} minimum and maximum of , can be used to
signify observability or sensitivity of the future -decay
experiments. Given current neutrino oscillation data, the possibility of
is found to be
very small.Comment: 9 pages, 3 figures, version to appear in Eur. Phys. J.
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