28,720 research outputs found
Baryogenesis from Dark Sector
We propose a novel mechanism to generate a suitable baryon asymmetry from
dark (hidden) sector. This is a Baryogenesis through a reverse pathway of the
"asymmetric dark matter" scenario. In the mechanism, the asymmetry of dark
matter is generated at first, and it is partially transferred into a baryon
asymmetry in the standard model sector. This mechanism enables us not only to
realize the generation of the baryon asymmetry but also to account for the
correct amount of dark matter density in the present universe within a simple
framework.Comment: 7 page
Moments of a single entry of circular orthogonal ensembles and Weingarten calculus
Consider a symmetric unitary random matrix
from a circular orthogonal ensemble. In this paper, we study moments of a
single entry . For a diagonal entry we give the explicit
values of the moments, and for an off-diagonal entry we give leading
and subleading terms in the asymptotic expansion with respect to a large matrix
size . Our technique is to apply the Weingarten calculus for a
Haar-distributed unitary matrix.Comment: 17 page
Generalized -conformal change and special Finsler spaces
In this paper, we investigate the change of Finslr metrics which we refer to as a
generalized -conformal change. Under this change, we study some special
Finsler spaces, namely, quasi C-reducible, semi C-reducible, C-reducible,
-like, -like and -like Finsler spaces. We also obtain the
transformation of the T-tensor under this change and study some interesting
special cases. We then impose a certain condition on the generalized
-conformal change, which we call the b-condition, and investigate the
geometric consequences of such condition. Finally, we give the conditions under
which a generalized -conformal change is projective and generalize some
known results in the literature.Comment: References added, some modifications are performed, LateX file, 24
page
Three-Dimensional Evolution of the Parker Instability under a Uniform Gravity
Using an isothermal MHD code, we have performed three-dimensional,
high-resolution simulations of the Parker instability. The initial equilibrium
system is composed of exponentially-decreasing isothermal gas and magnetic
field (along the azimuthal direction) under a uniform gravity. The evolution of
the instability can be divided into three phases: linear, nonlinear, and
relaxed. During the linear phase, the perturbations grow exponentially with a
preferred scale along the azimuthal direction but with smallest possible scale
along the radial direction, as predicted from linear analyses. During the
nonlinear phase, the growth of the instability is saturated and flow motion
becomes chaotic. Magnetic reconnection occurs, which allows gas to cross field
lines. This, in turn, results in the redistribution of gas and magnetic field.
The system approaches a new equilibrium in the relaxed phase, which is
different from the one seen in two-dimensional works. The structures formed
during the evolution are sheet-like or filamentary, whose shortest dimension is
radial. Their maximum density enhancement factor relative to the initial value
is less than 2. Since the radial dimension is too small and the density
enhancement is too low, it is difficult to regard the Parker instability alone
as a viable mechanism for the formation of giant molecular clouds.Comment: 8 pages of text, 4 figures (figure 2 in degraded gif format), to
appear in The Astrophysical Journal Letters, original quality figures
available via anonymous ftp at
ftp://ftp.msi.umn.edu/pub/users/twj/parker3d.uu or
ftp://canopus.chungnam.ac.kr/ryu/parker3d.u
Uncertainty principle for proper time and mass
We review Bohr's reasoning in the Bohr-Einstein debate on the photon box
experiment. The essential point of his reasoning leads us to an uncertainty
relation between the proper time and the rest mass of the clock. It is shown
that this uncertainty relation can be derived if only we take the fundamental
point of view that the proper time should be included as a dynamic variable in
the Lagrangian describing the system of the clock. Some problems and some
positive aspects of our approach are then discussed.Comment: 15 pages, accepted for publication in J. Math. Phy
Multiple finite Riemann zeta functions
Observing a multiple version of the divisor function we introduce a new zeta
function which we call a multiple finite Riemann zeta function. We utilize some
-series identity for proving the zeta function has an Euler product and
then, describe the location of zeros. We study further multi-variable and
multi-parameter versions of the multiple finite Riemann zeta functions and
their infinite counterparts in connection with symmetric polynomials and some
arithmetic quantities called powerful numbers.Comment: 19 page
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