315,035 research outputs found
Dual versions of N=2 supergravity and spontaneous supersymmetry breaking
In this paper, using a model of N=2 supergravity - vector multiplets
interaction with the scalar field geometry as an
example, we show that even when the geometry is fixed one can have a whole
family of the Lagrangians that differ by the vector field duality
transformations. As a byproduct, for this geometry we have constructed a model
of (m-1) vector multiplets interacting with the hidden sector admitting
spontaneous supersymmetry breaking with two arbitrary scales and without a
cosmological term.Comment: 10 pages, LaTeX, IHEP preprint 94-9
On Wilson Criterion
U(1) gauge theory with the Villain action on a cubic lattice approximation of
three- and four-dimensional torus is considered. The naturally chosen
correlation functions converge to the correlation functions of the R-gauge
electrodynamics on three- and four-dimensional torus as the lattice spacing
approaches zero only for the special scaling. This special scaling depends on a
choice of a correlation function system. Another scalings give the degenerate
continuum limits. The Wilson criterion for the confinement is ambiguous. The
asymptotics of the smeared Wilson loop integral for the large loop perimeters
is defined by the density of the loop smearing over a torus which is
transversal to the loop plane. When the initial torus radius tends to infinity
the correlation functions converge to the correlation functions of the R-gauge
Euclidean electrodynamics.Comment: latex, 6 page
Interaction of instantons in a gauge theory forcing their identical orientation
A gauge theory model in which there exists a specific interaction between
instantons is considered. An effective action describing this interaction
possesses a minimum when the instantons have identical orientation. The
considered interaction might provide a phase transition into the state where
instantons have a preferred orientation. This phase of the gauge-field theory
is important because it can give the description of gravity in the framework of
the gauge theory.Comment: 8 pages, Revte
The nuclear electric polarizability of 6He
We present an estimate of the nuclear electric polarizability of the 6He halo
nucleus based on six-body microscopic calculations. Wave functions are obtained
from semi-realistic two-body interactions using the hyperspherical harmonics
expansion method. The polarizability is calculated as a sum rule of the dipole
response function using the Lanczos algorithm and also by integrating the
photo-absorption cross section calculated via the Lorentz integral transform
method. We obtain alpha_E=1.00(14) fm^3, which is much smaller than the
published value 1.99(40) fm^3 extracted from experimental data. This points
towards a potential disagreement between microscopic theories and experimental
observations.Comment: 8 pages, 8 figures, minor changes, added error analysi
Experimental observation of the longitudinal plasma excitation in intrinsic Josephson junctions
We have investigated the current-voltage characteristics (IVCs) of intrinsic
Josephson junctions (IJJs). Recently, it is predicted that the longitudinal
plasma wave can be excited by the parametric resonance in IJJs. Such an
excitation induces a singularity called as breakpoint region around switch back
region in the IVC. We have succeeded in the observation of the breakpoint
region in the IVC of the mesa with 5 IJJs at 4.2 K. Furthermore, it is found
that the temperature dependence of the breakpoint current is in agreement with
the theoretical prediction. This suggests that the wave number of the excited
plasma wave varies with temperature.Comment: 7 pages, 7 figures. Dubna-Nano2008, Accepted for JPCS
On the problem of catastrophic relaxation in superfluid 3-He-B
In this Letter we discussed the parametric instability of texture of
homogeneous (in time) spin precession, explaining how spatial inhomogeneity of
the texture may change the threshold of the instability in comparison with
idealized spatial homogeneous case, considered in our JETP Letter \textbf{83},
530 (2006), cond-mat/0605386. This discussion is inspired by critical Comment
of I.A. Fomin (cond-mat/0606760) related to the above questions. In addition we
considered here results of direct numerical simulations of the full
Leggett-Takagi equation of motion for magnetization in superfluid 3He-B and
experimental data for magnetic field dependence of the catastrophic relaxation,
that provide solid support of the theory of this phenomenon, presented in our
2006 JETP Letter.Comment: 5 pages, 1 fig. included, JETP Lett. style, submitted to JETP Lett.
as response to Comment cond-mat/060676
Direct photon spectrum and elliptic flow produced from Pb+Pb collisions at TeV at the CERN Large Hadron Collider within an integrated hydrokinetic model
The photon transverse momentum spectrum and its anisotropy from Pb+Pb
collisions at the CERN Large Hadron Collider energy TeV
are investigated within the integrated hydrokinetic model (iHKM). Photon
production is accumulated from the different processes at the various stages of
relativistic heavy ion collisions: from the primary hard photons of very early
stage of parton collisions to the thermal photons from equilibrated quark-gluon
and hadron gas stages. Along the way a hadronic medium evolution is treated in
two distinct, in a sense opposite, approaches: chemically equilibrated and
chemically frozen system expansion. Studying the centrality dependence of the
results obtained allows us to conclude that a relatively strong transverse
momentum anisotropy of thermal radiation is suppressed by prompt photon
emission which is an isotropic. We find out that this effect is getting
stronger as centrality increases because of the simultaneous increase in the
relative contribution of prompt photons in the soft part of the spectra. The
substantial results obtained in iHKM with nonzero viscosity () for
photon spectra and coefficients are mostly within the error bars of
experimental data, but there is some systematic underestimation of both
observables for the near central events. We claim that a situation could be
significantly improved if an additional photon radiation that accompanies the
presence of a deconfined environment is included. Since a matter of a
space-time layer where hadronization takes place is actively involved in
anisotropic transverse flow, both positive contributions to the spectra and
are considerable, albeit such an argument needs further research and
elaboration.Comment: 21 pages, 6 figure
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