72 research outputs found
Gauged Dimension Bubbles
Some of the peculiar electrodynamical effects associated with gauged
``dimension bubbles'' are presented. Such bubbles, which effectively enclose a
region of 5d spacetime, can arise from a 5d theory with a compact extra
dimension. Bubbles with thin domain walls can be stabilized against total
collapse by the entrapment of light charged scalar bosons inside the bubble,
extending the idea of a neutral dimension bubble to accommodate the case of a
gauged U(1) symmetry. Using a dielectric approach to the 4d dilaton-Maxwell
theory, it is seen that the bubble wall is almost totally opaque to photons,
leading to a new stabilization mechanism due to trapped photons. Photon
dominated bubbles very slowly shrink, resulting in a temperature increase
inside the bubble. At some critical temperature, however, these bubbles
explode, with a release of radiation.Comment: 14 pages, no figures; to appear in Phys.Rev.
Investigation into O(N) Invariant Scalar Model Using Auxiliary-Mass Method at Finite Temperature
Using auxiliary-mass method, O(N) invariant scalar model is investigated at
finite temperature. This mass and an evolution equation allow us to calculate
an effective potential without an infrared divergence. Second order phase
transition is indicated by the effective potential. The critical exponents are
determined numerically.Comment: LaTex 8 pages with 3 eps figure
Q-ball formation: Obstacle to Affleck-Dine baryogenesis in the gauge-mediated SUSY breaking ?
We consider the Affleck-Dine baryogenesis comprehensively in the minimal
supersymmetric standard model with gauge-mediated supersymmetry breaking.
Considering the high temperature effects, we see that the Affleck-Dine field is
naturally deformed into the form of the Q ball. In the natural scenario where
the initial amplitude of the field and the A-terms are both determined by the
nonrenormalizable superpotential, we obtain only very a narrow allowed region
in the parameter space in order to explain the baryon number of the universe
for the case that the Q-ball formation occurs just after baryon number
production. Moreover, most of the parameter sets suited have already been
excluded by current experiments. We also find new situations in which the
Q-ball formation takes place rather late compared with baryon number creation.
This situation is more preferable, since it allows a wider parameter region for
naturally consistent scenarios, although it is still difficult to realize in
the actual cosmological scenario.Comment: 27 pages, RevTeX, 21 postscript figures included. The version to be
publishe
The O(N) Model at Finite Temperature: Renormalization of the Gap Equations in Hartree and Large-N Approximation
The temperature dependence of the sigma meson and pion masses is studied in
the framework of the O(N) model. The Cornwall-Jackiw-Tomboulis formalism is
applied to derive gap equations for the masses in the Hartree and large-N
approximations. Renormalization of the gap equations is carried out within the
cut-off and counter-term renormalization schemes. A consistent renormalization
of the gap equations within the cut-off scheme is found to be possible only in
the large-N approximation and for a finite value of the cut-off. On the other
hand, the counter-term scheme allows for a consistent renormalization of both
the large-N and Hartree approximations. In these approximations, the meson
masses at a given nonzero temperature depend in general on the choice of the
cut-off or renormalization scale. As an application, we also discuss the
in-medium on-shell decay widths for sigma mesons and pions at rest.Comment: 21 pages, 6 figures, typos corrected and refs. added, accepted in
Journal of Physics
Topological Mechanism of Superconductivity
We outline the basic ideas of the topological mechanisms of
superconductivity. A gauged model of correlated electronic system where a
topological fluid is formed as a result of a strong interaction is discussed.Comment: 38 pages, latex, no figure
Exact Formulas and Simple CP dependence of Neutrino Oscillation Probabilities in Matter with Constant Density
We investigate neutrino oscillations in constant matter within the context of
the standard three neutrino scenario. We derive an exact and simple formula for
the oscillation probability applicable to all channels. In the standard
parametrization, the probability for transition can
be written in the form without any
approximation using CP phase . For
transition, the linear term of is added and the probability can
be written in the form . We give the CP dependences of
the probability for other channels. We show that the probability for each
channel in matter has the same form with respect to as in vacuum. It
means that matter effects just modify the coefficients , , and .
We also give the exact expression of the coefficients for each channel.
Furthermore, we show that our results with respect to CP dependences are
reproduced from the effective mixing angles and the effective CP phase
calculated by Zaglauer and Schwarzer. Through the calculation, a new identity
is obtained by dividing the Naumov-Harrison-Scott identity by the Toshev
identity.Comment: 12 pages, RevTeX4 style, changed title, minor correction
Constraints on long-baseline neutrino oscillation probabilities and CP asymmetries from neutrino oscillation data
We consider long-baseline neutrino oscillations in the framework of two
schemes with mixing of four massive neutrinos which can accommodate all the
existing indications in favour of neutrino mixing. Within these schemes, we
derive bounds on the oscillation probabilities and the CP-odd
neutrino-antineutrino asymmetries in long-baseline experiments. Using the
results of short-baseline neutrino oscillation experiments, we obtain rather
strong upper bounds on the long-baseline probabilities 1-P(nu_e->nu_e) and
P(nu_mu->nu_e). Nevertheless, the projected sensitivities of the MINOS and
ICARUS experiments are better than our bounds. We also show that there are no
corresponding constraints for nu_mu->nu_mu and nu_mu->nu_tau long-baseline
oscillations and that the CP-odd asymmetry in the latter channel can reach the
maximal value allowed by the unitarity of the mixing matrix. Some schemes with
mixing of three neutrinos are also considered.Comment: 32 pages including 5 figures, RevTeX. New discussion of the matter
effect
Effects of Neutrino Oscillation on the Supernova Neutrino Spectrum
The effects of three-flavor neutrino oscillation on the supernova neutrino
spectrum are studied. We calculate the expected event rate and energy spectra,
and their time evolution at the Superkamiokande (SK) and the Sudbury Neutrino
Observatory (SNO), by using a realistic neutrino burst model based on numerical
simulations of supernova explosions. We also employ a realistic density profile
based on a presupernova model for the calculation of neutrino conversion
probability in supernova envelopes. These realistic models and numerical
calculations allow us to quantitatively estimate the effects of neutrino
oscillation in a more realistic way than previous studies. We then found that
the degeneracy of the solutions of the solar neutrino problem can be broken by
the combination of the SK and SNO detections of a future Galactic supernova.Comment: 10 pages, 14 figures, corrected versio
Numerical simulations of fragmentation of the Affleck-Dine condensate
We present numerical simulations of fragmentation of the Affleck-Dine
condensate in two spatial dimensions. We argue analytically that the final
state should consist of both Q-balls and anti-Q-balls in a state of maximum
entropy, with most of the balls small and relativistic. Such a behaviour is
found in simulations on a 100x100 lattice with cosmologically realistic
parameter values. During fragmentation process, we observe filament-like
texture in the spatial distribution of charge. The total charge in Q-balls is
found to be almost equal to the charge in anti-Q-balls and typically orders of
magnitude larger than charge asymmetry. Analytical considerations indicate
that, apart from geometrical factors, the results of the simulated two
dimensional case should apply also to the fully realistic three dimensional
case.Comment: 28 pages, 39 figure
Neutrino Oscillations and the Supernova 1987A Signal
We study the impact of neutrino oscillations on the interpretation of the
supernova (SN) 1987A neutrino signal by means of a maximum-likelihood analysis.
We focus on oscillations between with or
with those mixing parameters that would solve the solar
neutrino problem. For the small-angle MSW solution (, ), there are no
significant oscillation effects on the Kelvin-Helmholtz cooling signal; we
confirm previous best-fit values for the neutron-star binding energy and
average spectral temperature. There is only marginal overlap
between the upper end of the 95.4\% CL inferred range of and the lower end of the range of theoretical
predictions. Any admixture of the stiffer spectrum by
oscillations aggravates the conflict between experimentally inferred and
theoretically predicted spectral properties. For mixing parameters in the
neighborhood of the large-angle MSW solution (, ) the oscillations in the SN are adiabatic,
but one needs to include the regeneration effect in the Earth which causes the
Kamiokande and IMB detectors to observe different spectra. For
the solar vacuum solution (,
) the oscillations in the SN are nonadiabatic; vacuum
oscillations take place between the SN and the detector. If either of the
large-angle solutions were borne out by the upcoming round of solar neutrino
experiments, one would have to conclude that the SN~1987A
and/or spectra had been much softer than predicted by currentComment: Final version with very minor wording changes, to be published in
Phys. Rev.
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