1,986 research outputs found
Two-dimensional anyons and the temperature dependence of commutator anomalies
The temperature dependence of commutator anomalies is discussed on the
explicit example of particular (anyonic) field operators in two dimensions. The
correlation functions obtained show that effects of the non-zero temperature
might manifest themselves not only globally but also locally.Comment: 11 pages, LaTe
A String Approximation for Cooper Pair in High-T superconductivity
It is assumed that in some sense the High-T superconductivity is similar
to the quantum chromodynamics (QCD). This means that the phonons in High-T
superconductor have the strong interaction between themselves like to gluons in
the QCD. At the experimental level this means that in High-T superconductor
exists the nonlinear sound waves. It is possible that the existence of the
strong phonon-phonon interaction leads to the confinement of phonons into a
phonon tube (PT) stretched between two Cooper electrons like a hypothesized
flux tube between quark and antiquark in the QCD. The flux tube in the QCD
brings to a very strong interaction between quark-antiquark, the similar
situation can be in the High-T superconductor: the presence of the PT can
essentially increase the binding energy for the Cooper pair. In the first rough
approximation the PT can be approximated as a nonrelativistic string with
Cooper electrons at the ends. The BCS theory with such potential term is
considered. It is shown that Green's function method in the superconductivity
theory is a realization of discussed Heisenberg idea proposed by him for the
quantization of nonlinear spinor field. A possible experimental testing for the
string approximation of the Cooper pair is offered.Comment: Essential changes: (a) the section is added in which it is shown that
Green's function method in the superconductivity theory is a realization of
discussed Heisenberg quantization method; (b) Veneziano amplitude is
discussed as an approximation for the 4-point Green's function in High-T_c;
(c) it is shown that Eq.(53) has more natural solution on the layer rather
than on 3 dimensional spac
Cosmological constant and Euclidean space from nonperturbative quantum torsion
Heisenberg's nonperturbative quantization technique is applied to the
nonpertrubative quantization of gravity. An infinite set of equations for all
Green's functions is obtained. An approximation is considered where: (a) the
metric remains as a classical field; (b) the affine connection can be
decomposed into classical and quantum parts; (c) the classical part of the
affine connection are the Christoffel symbols; (d) the quantum part is the
torsion. Using a scalar and vector fields approximation it is shown that
nonperturbative quantum effects gives rise to a cosmological constant and an
Euclidean solution.Comment: title is changed. arXiv admin note: text overlap with arXiv:1201.106
Spherically Symmetric Solution for Torsion and the Dirac equation in 5D spacetime
Torsion in a 5D spacetime is considered. In this case gravitation is defined
by the 5D metric and the torsion. It is conjectured that torsion is connected
with a spinor field. In this case Dirac's equation becomes the nonlinear
Heisenberg equation. It is shown that this equation has a discrete spectrum of
solutions with each solution being regular on the whole space and having finite
energy. Every solution is concentrated on the Planck region and hence we can
say that torsion should play an important role in quantum gravity in the
formation of bubbles of spacetime foam. On the basis of the algebraic relation
between torsion and the classical spinor field in Einstein-Cartan gravity the
geometrical interpretation of the spinor field is considered as ``the square
root'' of torsion.Comment: 7 pages, REVTEX, essential changing of tex
Semiclassical Calculation of Multiparticle Scattering Cross Sections in Classicalizing Theories
It has been suggested in arXiv:1010.1415 that certain derivatively coupled
non-renormalizable scalar field theories might restore the perturbative
unitarity of high energy hard scatterings by classicalization, i.e. formation
of multiparticle states of soft quanta. Here we apply the semiclassical method
of calculating the multiparticle production rates to the scalar
Dirac-Born-Infeld (DBI) theory which is suggested to classicalize. We find that
the semiclassical method is applicable for the energies in the final state
above the cutoff scale of the theory L_*^{-1}. We encounter that the cross
section of the process two to N ceases to be exponentially suppressed for the
particle number in the final state N smaller than a critical particle number
N_{crit} ~ (E L_*)^{4/3}. It coincides with the typical particle number
produced in two-particle collisions at high energies predicted by
classicalization arguments.Comment: 17 pages, 4 figures, v2. Minor changes to match the published versio
Kinetic energy driven superconductivity, the origin of the Meissner effect, and the reductionist frontier
Is superconductivity associated with a lowering or an increase of the kinetic
energy of the charge carriers? Conventional BCS theory predicts that the
kinetic energy of carriers increases in the transition from the normal to the
superconducting state. However, substantial experimental evidence obtained in
recent years indicates that in at least some superconductors the opposite
occurs. Motivated in part by these experiments many novel mechanisms of
superconductivity have recently been proposed where the transition to
superconductivity is associated with a lowering of the kinetic energy of the
carriers. However none of these proposed unconventional mechanisms explores the
fundamental reason for kinetic energy lowering nor its wider implications. Here
I propose that kinetic energy lowering is at the root of the Meissner effect,
the most fundamental property of superconductors. The physics can be understood
at the level of a single electron atom: kinetic energy lowering and enhanced
diamagnetic susceptibility are intimately connected. According to the theory of
hole superconductivity, superconductors expel negative charge from their
interior driven by kinetic energy lowering and in the process expel any
magnetic field lines present in their interior. Associated with this we predict
the existence of a macroscopic electric field in the interior of
superconductors and the existence of macroscopic quantum zero-point motion in
the form of a spin current in the ground state of superconductors (spin
Meissner effect). In turn, the understanding of the role of kinetic energy
lowering in superconductivity suggests a new way to understand the fundamental
origin of kinetic energy lowering in quantum mechanics quite generally
The Evolution of Universe with th B-I Type Phantom Scalar Field
We considered the phantom cosmology with a lagrangian ,
which is original from the nonlinear Born-Infeld type scalar field with the
lagrangian . This cosmological model can explain the
accelerated expansion of the universe with the equation of state parameter
. We get a sufficient condition for a arbitrary potential to admit a
late time attractor solution: the value of potential at the critical
point should be maximum and large than zero. We study a specific
potential with the form of
via phase plane
analysis and compute the cosmological evolution by numerical analysis in
detail. The result shows that the phantom field survive till today (to account
for the observed late time accelerated expansion) without interfering with the
nucleosynthesis of the standard model(the density parameter
at the equipartition epoch), and also avoid the
future collapse of the universe.Comment: 17 pages, 10 figures,typos corrected, references added,figures added
and enriched, title changed, main result remaine
Diffractive Vector Meson Photoproduction from Dual String Theory
We study diffractive vector meson photoproduction using string theory via
AdS/CFT. The large behavior of the cross sections for the scattering of the
vector meson on a proton is dominated by the soft Pomeron, , where from the string theory model of
\cite{nastase2}, is approximately 1/7 below 10 GeV, and 1/11 for
higher, but still sub-Froissart, energies. This is due to the production of
black holes in the dual gravity. In -photoproduction the mesonic Regge
poles do not contribute, so that we deal with a pure Pomeron contribution. This
allows for an experimental test. At the gauge theory "Planck scale" of about
1-2 GeV, the ratios of the soft Pomeron contributions to the photoproduction
cross-sections of different vector mesons involve not only the obvious quark
model factors, but also the Boltzmann factors , with the
temperature of the dual black hole. The presence of these factors is confirmed
in the experimental data for and
photoproduction and is compatible with the meager photoproduction
data. Throughout, we use vector meson dominance, and from the data we obtain
of about , i.e. the gauge theory "Planck scale," as expected.
The ratio of the experimental soft Pomeron onset scale GeV
and of the gauge theory Planck scale, GeV conforms to the
theoretical prediction of .Comment: 17 pages, 1 figure, late
Remarks on the Extended Characteristic Uncertainty Relations
Three remarks concerning the form and the range of validity of the
state-extended characteristic uncertainty relations (URs) are presented. A more
general definition of the uncertainty matrix for pure and mixed states is
suggested. Some new URs are provided.Comment: LaTex, 4 pages, no figure
Proposal to improve the behaviour of self-energy contributions to the S-matrix
A simple modification of the definition of the S-matrix is proposed. It is
expected that the divergences related to nonzero self-energies are considerably
milder with the modified definition than with the usual one. This conjecture is
verified in a few examples using perturbation theory. The proposed formula is
written in terms of the total Hamiltonian operator and a free Hamiltonian
operator and is therefore applicable in any case when these Hamiltonian
operators are known.Comment: 24 pages, 1 figure; v2: revised version; v3: section 3 improved.
Accepted for publication in Central European Journal of Physics; v4: minor
text misprints correcte
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