6,485 research outputs found
One-loop Neutron Electric Dipole Moment from Supersymmetry without R-parity
We present a detailed analysis together with exact numerical calculations on
one-loop contributions to neutron electric dipole moment from supersymmetry
without R-parity, focusing on the gluino, chargino, and neutralino
contributions. Apart from the neglected family mixing among quarks, complete
formulae are given for the various contributions, through the quark dipole
operators, to which the present study is restricted. We discuss the structure
and main features of the R-parity violating contributions and the interplay
between the R-parity conserving and violating parameters. In particular, the
parameter combination , under the optimal
parametrization adopted, is shown to be solely responsible for the R-parity
violating contributions in the supersymmetric loop diagrams. While
could bear a complex phase, the latter is not
necessary to have a R-parity violating contribution.Comment: 43 pages Revtex with 15 eps- and 4 ps- figure files incoporated;
proofread version to be published in Phys. Rev.
On the EDM Cancellations in D-brane models
We analyze the possibility of simultaneous electron, neutron, and mercury
electric dipole moment (EDM) cancellations in the mSUGRA and D--brane models.
We find that the mercury EDM constraint practically rules out the cancellation
scenario in D-brane models whereas in the context of mSUGRA it is still allowed
with some fine-tuning.Comment: 10 pages, to appear in Phys. Rev. Let
Effects of CP Violation on Event Rates in the Direct Detection of Dark Matter
A full analytic analysis of the effects of CP violating phases on the event
rates in the direct detection of dark matter in the scattering of neutralinos
from nuclear targets is given. The analysis includes CP violating phases in
softly broken supersymmetry in the framework of the minimal supersymmetric
standard model (MSSM) when generational mixings are ignored. A numerical
analysis shows that large CP violating phases including the constraints from
the experimental limits on the neutron and the electron electric dipole moment
(EDM) can produce substantial effects on the event rates in dark matter
detectors.Comment: 17 pages, LaTex, including 2 figures; revised version to appear in
the Physical Review
Electron and Neutron Electric Dipole Moments in the Focus Point Scenario of SUGRA Model
We estimate the electron and neutron electric dipole moments in the focus
point scenario of the minimal SUGRA model corresponding to large sfermion
masses and moderate to large . There is a viable region of moderate
fine-tuning in the parameter space, around , where the
experimental limits on these electric dipole moments can be satisfied without
assuming unnaturally small phase angles. But the fine-tuning constraints become
more severe for .Comment: 16 pages, LaTeX, 4 postscript figures. Very minor changes made in
only a few sentences for clarification. Final version to appear in Phys. Rev.
CP Violation and Dark Matter
A brief review is given of the effects of CP violation on the direct
detection of neutralinos in dark matter detectors. We first summarize the
current developments using the cancellation mechanism which allows for the
existence of large CP violating phases consistent with experimental limits on
the electron and on the neutron electric dipole moments in a broad class of
SUSY, string and D brane models. We then discuss their effects on the
scattering of neutralinos from quarks and on the event rates. It is found that
while CP effects on the event rates can be enormous such effects are reduced
significantly with the imposition of the EDM constraints. However, even with
the inclusion of the EDM constraints the effects are still very significant and
should be included in a precision prediction of event rates in any SUSY, string
or D brane model.Comment: Based on an invited talk at the conference "Sources and Detection of
Dark Matter in the Universe", at Marina del Rey, CA, Feb. 23-25, 2000; 12
pages, Latex including 2 figure
A Resolution to the Supersymmetric CP Problem with Large Soft Phases via D-branes
We examine the soft supersymmetry breaking parameters that result from
various ways of embedding the Standard Model (SM) on D-branes within the Type I
string picture, allowing the gaugino masses and to have large CP-
violating phases. One embedding naturally provides the relations among soft
parameters to satisfy the electron and neutron electric dipole moment
constraints even with large phases, while with other embeddings large phases
are not allowed. The string models provide some motivation for large phases in
the soft breaking parameters. The results generally suggest how low energy data
might teach us about Planck scale physics.Comment: 11 pages, 2 eps figures; revised references and updated tex
Mixing of the CP Even and the CP Odd Higgs Bosons and the EDM Constraints
The mixing among the CP even and the CP odd neutral Higgs bosons of MSSM by
one loop induced effects in the presence of CP phases is investigated using
three different mechanisms to satisfy the EDM constraints, i.e., a fine tuning
of phases, a heavy sparticle spectrum, and the cancellation mechanism. It is
shown that if a mixing effect among the CP even and the CP odd Higgs bosons is
observed experimentally, then it is only the cancellation mechanism that can
survive under the naturalness constraint.Comment: 14 pages, Latex and 4figures. A new paragraph is added and few more
references. One figure is modified. To appear in Phys. Rev.
Probing SUSY-induced CP violations at B factories
In the minimal supersymmetric standard model (MSSM), the \mu-parameter and
the trilinear coupling A_t may be generically complex and can affect various
observables at B factories. Imposing the edm constraints, we find that there is
no new large phase shift in the B^0 - \bar{B^0} mixing, CP violating dilepton
asymmetry is smaller than 0.1 %, and the direct CP violation in B\to X_s \gamma
can be as large as \sim \pm 16 %.Comment: 4 pages, 2 figures. Version to appear in Phys. Rev. Let
First-principles calculation of the temperature dependence of the optical response of bulk GaAs
A novel approach has been developed to calculate the temperature dependence
of the optical response of a semiconductor. The dielectric function is averaged
over several thermally perturbed configurations that are extracted from
molecular dynamic simulations. The calculated temperature dependence of the
imaginary part of the dielectric function of GaAs is presented in the range
from 0 to 700 K. This approach that explicitly takes into account lattice
vibrations describes well the observed thermally-induced energy shifts and
broadening of the dielectric function.Comment: 6 pages, 3 figure
Anomalous relaxation and self-organization in non-equilibrium processes
We study thermal relaxation in ordered arrays of coupled nonlinear elements
with external driving. We find, that our model exhibits dynamic
self-organization manifested in a universal stretched-exponential form of
relaxation. We identify two types of self-organization, cooperative and
anti-cooperative, which lead to fast and slow relaxation, respectively. We give
a qualitative explanation for the behavior of the stretched exponent in
different parameter ranges. We emphasize that this is a system exhibiting
stretched-exponential relaxation without explicit disorder or frustration.Comment: submitted to PR
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