3,603 research outputs found
A cosmological bound on mass difference
We demonstrate that CPT-violation due to mass difference generates
a non-zero photon mass. As a result the cosmological bounds on the photon mass
lead to the bounds on mass difference which are at least by 10 orders
of magnitude stronger than the direct experimental bound.Comment: 8 page
Distribution of averages in a correlated Gaussian medium as a tool for the estimation of the cluster distribution on size
Calculation of the distribution of the average value of a Gaussian random
field in a finite domain is carried out for different cases. The results of the
calculation demonstrate a strong dependence of the width of the distribution on
the spatial correlations of the field. Comparison with the simulation results
for the distribution of the size of the cluster indicates that the distribution
of an average field could serve as a useful tool for the estimation of the
asymptotic behavior of the distribution of the size of the clusters for "deep"
clusters where value of the field on each site is much greater than the rms
disorder.Comment: 15 pages, 6 figures, RevTe
Slim accretion discs: a model for ADAF-SLE transitions
We numerically construct slim, global, vertically integrated models of
optically thin, transonic accretion discs around black holes, assuming a
regularity condition at the sonic radius and boundary conditions at the outer
radius of the disc and near the black hole. In agreement with several previous
studies, we find two branches of shock-free solutions, in which the cooling is
dominated either by advection, or by local radiation. We also confirm that the
part of the accretion flow where advection dominates is in some circumstances
limited in size: it does not extend beyond a certain outer limiting radius. New
results found in our paper concern the location of the limiting radius and
properties of the flow near to it. In particular, we find that beyond the
limiting radius, the advective dominated solutions match on to Shapiro,
Lightman & Eardley (SLE) discs through a smooth transition region. Therefore,
the full global solutions are shock-free and unlimited in size. There is no
need for postulating an extra physical effect (e.g. evaporation) for triggering
the ADAF-SLE transition. It occurs due to standard accretion processes
described by the classic slim disc equations.Comment: 12 pages, 7 figures, MNRAS accepte
Energetic disorder at the metal/organic semiconductor interface
The physics of organic semiconductors is dominated by the effects of
energetic disorder. We show that image forces reduce the electrostatic
component of the total energetic disorder near an interface with a metal
electrode. Typically, the variance of energetic disorder is dramatically
reduced at the first few layers of organic semiconductor molecules adjacent to
the metal electrode. Implications for charge injection into organic
semiconductors are discussed.Comment: 9 pages, 2 figure
Calculation of nuclear-spin-dependent parity nonconservation in s-d transitions of Ba, Yb and Ra ions
We use correlation potential and many-body perturbation theory techniques to
calculate spin-independent and nuclear spin-dependent parts of the parity
nonconserving amplitudes of the transitions between the ground state
and the excited state of Ba and Yb and between the
ground state and the excited state of Ra. The results
are presented in a form convenient for extracting of the constants of
nuclear-spin-dependent interaction (such as, e.g., anapole moment) from the
measurements.Comment: 9 pages, 8 tables, no figure
Disintegration and expansion of wormholes
We consider the process of catastrophic expansion of a spacelike wormhole
after a violation of its equilibrium state. The dynamics of deformation of the
comoving reference frame is investigated. We show that the deformation has a
very specific anisotropic feature. The statement made earlier by other authors,
that in the process of expanding the wormhole connecting two universes these
universes ultimately unite into one universe, is not correct. We show that the
transverse size of the wormhole (its throat) increases and the length of the
corridor decreases which does not correspond to the de Sitter model
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