5,348 research outputs found
Supersymmetry preserving and breaking degenerate vacua, and radiative moduli stabilization
We propose a new type of moduli stabilization scenario where the
supersymmetric and supersymmetry-breaking minima are degenerate at the leading
level. The inclusion of the loop-corrections originating from the matter fields
resolves this degeneracy of vacua. Light axions are predicted in one of our
models.Comment: 18 pages, 14 figure
New effective interaction for -shell nuclei and its implications for the stability of the ==28 closed core
The effective interaction GXPF1 for shell-model calculations in the full
shell is tested in detail from various viewpoints such as binding energies,
electro-magnetic moments and transitions, and excitation spectra. The
semi-magic structure is successfully described for or Z=28 nuclei,
Mn, Fe, Co and Ni, suggesting the
existence of significant core-excitations in low-lying non-yrast states as well
as in high-spin yrast states. The results of odd-odd nuclei, Co
and Cu, also confirm the reliability of GXPF1 interaction in the isospin
dependent properties. Studies of shape coexistence suggest an advantage of
Monte Carlo Shell Model over conventional calculations in cases where
full-space calculations still remain too large to be practical.Comment: 29pages, 26figures, to be published in Physical Review
Superconductivity and antiferromagnetism in the two-dimensional Hubbard model: a variational study
A variational ground state of the repulsive Hubbard model on a square lattice
is investigated numerically for an intermediate coupling strength (U = 8t) and
for moderate sizes (from 6 x 6 to 10 x 10). Our ansatz is clearly superior to
other widely used variational wave functions. The results for order parameters
and correlation functions provide new insight for the antiferromagnetic state
at half filling as well as strong evidence for a superconducting phase away
from half filling.Comment: 4 pages, 4 figure
Gauge coupling unification in SO(32) heterotic string theory with magnetic fluxes
We study heterotic string theory on torus with magnetic fluxes.
Non-vanishing fluxes can lead to non-universal gauge kinetic functions for
which is the important features of
heterotic string theory in contrast to the theory. It is found
that the experimental values of gauge couplings are realized with
values of moduli fields based on the realistic models with the gauge symmetry and three chiral generations of quarks and
leptons without chiral exotics.Comment: 20 pages, 9 figure
El Chichon aerosols in the stratosphere: Analyses of lidar data and calculations of radiation budget
Lidar observation at Fukuoka has provided over four years the data of ElChichon aerosols in the stratosphere. Analyses of the data show that an enormous amount of volcanic aerosols has continuously decreased since the beginning of 1983 with significant fluctuations. These fluctuations reveal themselves as a seasonal variation of aerosol content with a maximum in winter-spring and a minimum in summer. The vertical structure of the aerosol layer also shows the seasonal variation. Although the height of a peak around 18 km in the vertical profile of scattering ratio show littel variation, the higher second peak appears frequently from late fall and the lower third peak from late winter to late spring just as two and more tropopauses appear in these periods. The mechanism which causes the seasonal variation will be discussed in terms of the transport by the atmoshperic circulation and the removal through the tropopause gap. Radiation budget in the atmosphere was calculated taking into account the large amount of aerosols observed in the early stages of the El Chichon event. The heating rate of the atmosphere is more than 1 K in the bottom region of the stratosphere even in the nighttime. The possible effect of the volcanic aerosols on the other geophysical phenomena will be discussed using the calculated values of the heating rate
Transition to complete synchronization in phase coupled oscillators with nearest neighbours coupling
We investigate synchronization in a Kuramoto-like model with nearest
neighbour coupling. Upon analyzing the behaviour of individual oscillators at
the onset of complete synchronization, we show that the time interval between
bursts in the time dependence of the frequencies of the oscillators exhibits
universal scaling and blows up at the critical coupling strength. We also bring
out a key mechanism that leads to phase locking. Finally, we deduce forms for
the phases and frequencies at the onset of complete synchronization.Comment: 6 pages, 4 figures, to appear in CHAO
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