532 research outputs found
Kaluza's theory in generalized coordinates
Maxwell's equations can be obtained in generalized coordinates by considering
the electromagnetic field as an external agent. The work here presented shows
how to obtain the electrodynamics for a charged particle in generalized
coordinates eliminating the concept of external force. Based on Kaluza's
formalism, the one here presented extends the 5x5 metric into a 6x6 space-time
giving enough room to include magnetic monopoles in a very natural way.Comment: 11 pages, RevTex. Accepted for publication in the Journal of
Matematical Physic
A class of colliding waves in metric-affine gravity, nonmetricity and torsion shock waves
By using our recent generalization of the colliding waves concept to
metric-affine gravity theories, and also our generalization of the advanced and
retarded time coordinate representation in terms of Jacobi functions, we find a
general class of colliding wave solutions with fourth degree polynomials in
metric-affine gravity. We show that our general approach contains the standard
second degree polynomials colliding wave solutions as a particular case.Comment: 13 pages, latex, to appear in J.Math.Phy
Transition from Diffusive to Localized Regimes in Surface Corrugated Optical Waveguides
Exact calculations of the transmittance of surface corrugated optical
waveguides are presented. The elastic scattering of diffuse light or other
electromagnetic waves from a rough surface induces a diffusive transport along
the waveguide axis. As the length of the corrugated part of the waveguide
increases, a transition from the diffusive to the localized regime is observed.
This involves an analogy with electron conduction in nanowires, and hence, a
concept analogous to that of ``resistance'' can be introduced. We show an
oscillatory behavior of both the elastic mean free path and the localization
length versus the wavelength.Comment: 3 pages, REVTEX, 3 PS figure
Study of SU(3) vortex-like configurations with a new maximal center gauge fixing method
We present a new way of fixing the gauge to (direct) maximal center gauge in
SU(N) Yang-Mills theory and apply this method to SU(3) configurations which are
vortex-like. We study the structure of the Z_3 configurations obtained after
center-projecting the SU(3) ones.Comment: 11 pages, 2 figures. To appear in PL
Testing Chiral Dynamics in Pionic Atoms
The energy dependence of chirally expanded pi N isoscalar and isovector
amplitudes b_0(E) and b_1(E) respectively, for zero-momentum off shell pions
near threshold, is used to impose the minimal substitution requirement E -> E -
V_c on the properly constructed pion optical potential within a large-scale fit
to 100 pionic-atom data across the periodic table which also include the
recently established `deeply bound' pionic atoms of Pb and Sn. This fit cannot
be reconciled with the well known free-space values of the pi N threshold
amplitudes. In contrast, introducing the empirically known energy dependence
for on-shell pions leads to a better fit and to satisfactory values for the pi
N threshold amplitudes. The difference between these two approaches is briefly
discussed.Comment: 10 pages, 3 figures, submitted to PLB. Discussion section rewritten,
omitting an erroneous equation. Results and conclusions unchanged Accepted by
PL
Monte Carlo critical isotherms for Ising lattices
Monte Carlo investigations of magnetization versus field, , at the
critical temperature provide direct accurate results on the critical exponent
for one, two, three and four-dimensional lattices:
=0, =0.0666(2)1/15,
=0.1997(4)1/5,
=0.332(5)1/3. This type of Monte Carlo data on
, which is not easily found in studies of Ising lattices in the current
literature, as far as we know, defines extremely well the numerical value of
this exponent within very stringent limits.Comment: 5 pages, 4 figures. Sent to Europhysics Letter
Order-alpha_s^2 corrections to one-particle inclusive processes in DIS
We analyze the order- QCD corrections to semi-inclusive deep
inelastic scattering and present results for processes initiated by a gluon. We
focus in the most singular pieces of these corrections in order to obtain the
hitherto unknown NLO evolution kernels relevant for the non homogeneous QCD
scale dependence of these cross sections, and to check explicitly factorization
at this order. In so doing we discuss the prescription of overlapping
singularities in more than one variable.Comment: 16 pages, 9 eps figures. Uses revtex4 and feynm
Statistics of dressed modes in a thermal state
By a Wigner-function calculation, we evaluate the trace of a certain Gaussian
operator arising in the theory of a boson system subject to both finite
temperature and (weak) interaction. Thereby we rederive (and generalize) a
recent result by Kocharovsky, Kocharovsky, and Scully [Phys. Rev. A, vol. 61,
art. 053606 (2000)] in a way that is technically much simpler. One step uses a
special case of the response of Wigner functions to linear transformations, and
we demonstrate the general case by simple means. As an application we extract
the counting statistics for each mode of the Bose gas.Comment: to appear in Optics Communications, 10 page
Non-Linear Canonical Transformations in Classical and Quantum Mechanics
-Mechanics is a consistent physical theory which describes both classical
and quantum mechanics simultaneously through the representation theory of the
Heisenberg group. In this paper we describe how non-linear canonical
transformations affect -mechanical observables and states. Using this we
show how canonical transformations change a quantum mechanical system. We seek
an operator on the set of -mechanical observables which corresponds to the
classical canonical transformation. In order to do this we derive a set of
integral equations which when solved will give us the coherent state expansion
of this operator. The motivation for these integral equations comes from the
work of Moshinsky and a variety of collaborators. We consider a number of
examples and discuss the use of these equations for non-bijective
transformations.Comment: The paper has been improved in light of a referee's report. The paper
will appear in the Journal of Mathematical Physics. 24 pages, no figure
Multisymplectic Geometry and Multisymplectic Preissman Scheme for the KP Equation
The multisymplectic structure of the KP equation is obtained directly from
the variational principal. Using the covariant De Donder-Weyl Hamilton function
theories, we reformulate the KP equation to the multisymplectic form which
proposed by Bridges. From the multisymplectic equation, we can derive a
multisymplectic numerical scheme of the KP equation which can be simplified to
multisymplectic forty-five points scheme.Comment: 17 papges, 8 figure
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