72 research outputs found
Statistical Ensembles with Fluctuating Extensive Quantities
We suggest an extension of the standard concept of statistical ensembles.
Namely, we introduce a class of ensembles with extensive quantities fluctuating
according to an externally given distribution. As an example the influence of
energy fluctuations on multiplicity fluctuations in limited segments of
momentum space for a classical ultra-relativistic gas is considered.Comment: 4 pages, 2 figure
Kaluza-Klein 5D Ideas Made Fully Geometric
After the 1916 success of General relativity that explained gravity by adding
time as a fourth dimension, physicists have been trying to explain other
physical fields by adding extra dimensions. In 1921, Kaluza and Klein has shown
that under certain conditions like cylindricity (), the addition of the 5th dimension can explain the electromagnetic
field. The problem with this approach is that while the model itself is
geometric, conditions like cylindricity are not geometric. This problem was
partly solved by Einstein and Bergman who proposed, in their 1938 paper, that
the 5th dimension is compactified into a small circle so that in the
resulting cylindric 5D space-time the dependence on is
not macroscopically noticeable. We show that if, in all definitions of vectors,
tensors, etc., we replace with , then conditions like
cylindricity automatically follow -- i.e., these conditions become fully
geometric.Comment: 14 page
Transformation laws of the components of classical and quantum fields and Heisenberg relations
The paper recalls and point to the origin of the transformation laws of the
components of classical and quantum fields. They are considered from the
"standard" and fibre bundle point of view. The results are applied to the
derivation of the Heisenberg relations in quite general setting, in particular,
in the fibre bundle approach. All conclusions are illustrated in a case of
transformations induced by the Poincar\'e group.Comment: 22 LaTeX pages. The packages AMS-LaTeX and amsfonts are required. For
other papers on the same topic, view http://theo.inrne.bas.bg/~bozho/ . arXiv
admin note: significant text overlap with arXiv:0809.017
Computation of Casimir forces for dielectrics or intrinsic semiconductors based on the Boltzmann transport equation
The interaction between drifting carriers and traveling electromagnetic waves
is considered within the context of the classical Boltzmann transport equation
to compute the Casimir-Lifshitz force between media with small density of
charge carriers, including dielectrics and intrinsic semiconductors. We expand
upon our previous work [Phys. Rev. Lett. {\bf 101}, 163203 (2008)] and derive
in some detail the frequency-dependent reflection amplitudes in this theory and
compute the corresponding Casimir free energy for a parallel plate
configuration. We critically discuss the the issue of verification of the
Nernst theorem of thermodynamics in Casimir physics, and explicity show that
our theory satisfies that theorem. Finally, we show how the theory of drifting
carriers connects to previous computations of Casimir forces using spatial
dispersion for the material boundaries.Comment: 9 pages, 2 figures; Contribution to Proceedings of "60 Years of the
Casimir Effect", Brasilia, June 200
The R.I. Pimenov unified gravitation and electromagnetism field theory as semi-Riemannian geometry
More then forty years ago R.I. Pimenov introduced a new geometry --
semi-Riemannian one -- as a set of geometrical objects consistent with a
fibering He suggested the heuristic principle according to
which the physically different quantities (meter, second, coulomb etc.) are
geometrically modelled as space coordinates that are not superposed by
automorphisms. As there is only one type of coordinates in Riemannian geometry
and only three types of coordinates in pseudo-Riemannian one, a multiple
fibered semi-Riemannian geometry is the most appropriate one for the treatment
of more then three different physical quantities as unified geometrical field
theory.
Semi-Euclidean geometry with 1-dimensional fiber and
4-dimensional Minkowski space-time as a base is naturally interpreted as
classical electrodynamics. Semi-Riemannian geometry with the
general relativity pseudo-Riemannian space-time and 1-dimensional
fiber responsible for the electromagnetism, provides the unified field
theory of gravitation and electromagnetism. Unlike Kaluza-Klein theories, where
the 5-th coordinate appears in nondegenerate Riemannian or pseudo-Riemannian
geometry, the theory based on semi-Riemannian geometry is free from defects of
the former. In particular, scalar field does not arise.
PACS: 04.50.Cd, 02.40.-k, 11.10.KkComment: 16 pages, 2 figures. Submited to Physics of Atomic Nucle
Casimir-Polder force between an atom and a dielectric plate: thermodynamics and experiment
The low-temperature behavior of the Casimir-Polder free energy and entropy
for an atom near a dielectric plate are found on the basis of the Lifshitz
theory. The obtained results are shown to be thermodynamically consistent if
the dc conductivity of the plate material is disregarded. With inclusion of dc
conductivity, both the standard Lifshitz theory (for all dielectrics) and its
generalization taking into account screening effects (for a wide range of
dielectrics) violate the Nernst heat theorem. The inclusion of the screening
effects is also shown to be inconsistent with experimental data of Casimir
force measurements. The physical reasons for this inconsistency are elucidated.Comment: 10 pages, 1 figure; improved discussion; to appear in J. Phys. A:
Math. Theor. (Fast Track Communications
A q-deformed Aufbau Prinzip
A building principle working for both atoms and monoatomic ions is proposed
in this Letter. This principle relies on the q-deformed chain SO(4) > G where G
= SO(3)_q
Magnetic moment of the two-particle bound state in quantum electrodynamics
We have formulated the quasipotential method for the calculation of the
relativistic and radiative corrections to the magnetic moment of the
two-particle bound state in the case of particles with arbitrary spin. It is
shown that the g-factors of bound particles contain terms
depending on the particle spin. Numerical values for the g-factors of the
electron in the hydrogen atom and deuterium are obtained.Comment: Talk presented at Nuclear Physics Department Conference "Physics of
Fundamental Interactions" Russian Academy of Sciences, ITEP, Moscow, 27
November-1 December 2000. 11 pages, 1 figure uses linedraw.st
Obtainment of internal labelling operators as broken Casimir operators by means of contractions related to reduction chains in semisimple Lie algebras
We show that the In\"on\"u-Wigner contraction naturally associated to a
reduction chain of semisimple Lie algebras
induces a decomposition of the Casimir operators into homogeneous polynomials,
the terms of which can be used to obtain additional mutually commuting missing
label operators for this reduction. The adjunction of these scalars that are no
more invariants of the contraction allow to solve the missing label problem for
those reductions where the contraction provides an insufficient number of
labelling operators
Bose-Einstein Condensation in the Relativistic Pion Gas: Thermodynamic Limit and Finite Size Effects
We consider the Bose-Einstein condensation (BEC) in a relativistic pion gas.
The thermodynamic limit when the system volume goes to infinity as well as
the role of finite size effects are studied. At the scaled
variance for particle number fluctuations, ,
converges to finite values in the normal phase above the BEC temperature,
. It diverges as at the BEC line , and
at in a phase with the BE condensate. Possible
experimental signals of the pion BEC in finite systems created in high energy
proton-proton collisions are discussed
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