83 research outputs found
Gauge string in the fermion asymmetric matter
Two new effects of interaction of the gauge string with a homogeneous density
of fermions are considered in a gauge model with an anomalous coupling of
vector fields with fermions. First, the presence of an induced nonzero
magnetic-like helicity on the straight string is demonstrated. Second, it is
shown that the equation of motion of the string is modified by a nonlinear term
that can be decomposed into the correction to the string tension and an
additional force perpendicular to the tangent and normal vectors of the string.
Static configurations are found and their stability is studied.Comment: revtex, 9 pages, to appear in Phys. Lett.
The decay omega(782) -> 5 pi in chiral theory
The arguments are put forward that the many pion decays omega ->2 pi^+ 2 pi^-
pi^0 and pi^+ pi^- 3 pi^0 provide an ideal test site for testing the
predictions of chiral models of the vector meson decays into many pions. Using
the approach based on the Weinberg Lagrangian or, in a new language, the
Lagrangian of hidden local symmetry added with the term induced by the
anomalous Lagrangian of Wess and Zumino, the partial widths of these decays are
evaluated, and their excitation curves in e^+e^- annihilation are obtained. The
discussed are the perspectives of the experimental study of the decays omega ->
5 pi in e^+e^- annihilation and photoproduction.Comment: revtex, 12 pages include 2 ps figures; clarifying remarks and
references added, 17-fold reduction of filesize of fig1.ps. Accepted in Phys.
Lett.
Multipion decays of omega(782) and phi(1020)
Using the chiral model of pseudoscalar, vector, and axial vector mesons based
on the hidden local symmetry added with the terms induced by the Wess-Zumino
anomaly, the results of calculations of the branching fractions of the decays
omega(782) and phi(1020) mesons to the 2pi+ 2pi- pi0, pi+ pi -3pi0 multipion
states are presented.Comment: 4 pages. Talk presented by A.A. Kozhevnikov at the International
Workshop "e+e- Collisions from Phi to Psi", February 27-March 2, 2006, BINP,
Novosibirsk, Russian Federatio
Shot noise measurements in NS junctions and the semiclassical theory
We present a new analysis of shot noise measurements in normal
metal-superconductor (NS) junctions [X. Jehl et al., Nature 405, 50 (2000)],
based on a recent semiclassical theory. The first calculations at zero
temperature assuming quantum coherence predicted shot noise in NS contacts to
be doubled with respect to normal contacts. The semiclassical approach gives
the first opportunity to compare data and theory quantitatively at finite
voltage and temperature. The doubling of shot noise is predicted up to the
superconducting gap, as already observed, confirming that phase coherence is
not necessary. An excellent agreement is also found above the gap where the
noise follows the normal case.Comment: 2 pages, revtex, 2 eps figures, to appear in Phys. Rev.
X ray and electron nondestructive spectroscopic methods for thin films and interfaces study Application to SrTiO3 based heterostructures
Knotlike Cosmic Strings in The Early Universe
In this paper, the knotlike cosmic strings in the Riemann-Cartan space-time
of the early universe are discussed. It has been revealed that the cosmic
strings can just originate from the zero points of the complex scalar
quintessence field. In these strings we mainly study the knotlike
configurations. Based on the integral of Chern-Simons 3-form a topological
invariant for knotlike cosmic strings is constructed, and it is shown that this
invariant is just the total sum of all the self-linking and linking numbers of
the knots family. Furthermore, it is also pointed out that this invariant is
preserved in the branch processes during the evolution of cosmic strings
Nonlocal effects in the shot noise of diffusive superconductor - normal-metal systems
A cross-shaped diffusive system with two superconducting and two normal
electrodes is considered. A voltage is applied between the normal
leads. Even in the absence of average current through the superconducting
electrodes their presence increases the shot noise at the normal electrodes and
doubles it in the case of a strong coupling to the superconductors. The
nonequilibrium noise at the superconducting electrodes remains finite even in
the case of a vanishingly small transport current due to the absence of energy
transfer into the superconductors. This noise is suppressed by
electron-electron scattering at sufficiently high voltages.Comment: 4 pages, RevTeX, 2 eps figure
Positive cross-correlations induced by ferromagnetic contacts
Due to the Fermionic nature of carriers, correlations between electric
currents flowing through two different contacts attached to a conductor present
a negative sign. Possibility for positive cross-correlations has been
demonstrated in hybrid normal/superconductor structures under certain
conditions. In this paper we show that positive cross-correlations can be
induced, if not already present, in such structures by employing ferromagnetic
leads with magnetizations aligned anti-parallel to each other. We consider
three-terminal hybrid structures and calculate the mean-square correlations of
current fluctuations as a function of the bias voltage at finite temperature.Comment: 6 pages, 5 figures; accepted version by PRB, figures replace
Superconductive proximity effect in interacting disordered conductors
We present a general theory of the superconductive proximity effect in
disordered normal--superconducting (N-S) structures, based on the recently
developed Keldysh action approach. In the case of the absence of interaction in
the normal conductor we reproduce known results for the Andreev conductance G_A
at arbitrary relation between the interface resistance R_T and the diffusive
resistance R_D. In two-dimensional N-S systems, electron-electron interaction
in the Cooper channel of normal conductor is shown to strongly affect the value
of G_A as well as its dependence on temperature, voltage and magnetic field. In
particular, an unusual maximum of G_A as a function of temperature and/or
magnetic field is predicted for some range of parameters R_D and R_T. The
Keldysh action approach makes it possible to calculate the full statistics of
charge transfer in such structures. As an application of this method, we
calculate the noise power of an N-S contact as a function of voltage,
temperature, magnetic field and frequency for arbitrary Cooper repulsion in the
normal metal and arbitrary values of the ratio R_D/R_T.Comment: RevTeX, 28 pages, 18 PostScript figures; added and updated reference
Current noise in long diffusive SNS junctions in the incoherent MAR regime
Spectral density of current fluctuations at zero frequency is calculated for
a long diffusive SNS junction with low-resistive interfaces. At low
temperature, T << Delta, the subgap shot noise approaches linear voltage
dependence, S=(2/ 3R)(eV + 2Delta), which is the sum of the shot noise of the
normal conductor and voltage independent excess noise. This result can also be
interpreted as the 1/3-suppressed Poisson noise for the effective charge q =
e(1+2Delta/eV) transferred by incoherent multiple Andreev reflections (MAR). At
higher temperatures, anomalies of the current noise develop at the gap
subharmonics, eV = 2Delta/n. The crossover to the hot electron regime from the
MAR regime is analyzed in the limit of small applied voltages.Comment: improved version, to be published in Phys. Rev.
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