4,380 research outputs found
Generalized Hamilton-Jacobi equations for nonholonomic dynamics
Employing a suitable nonlinear Lagrange functional, we derive generalized
Hamilton-Jacobi equations for dynamical systems subject to linear velocity
constraints. As long as a solution of the generalized Hamilton-Jacobi equation
exists, the action is actually minimized (not just extremized)
Calculation of isotope shifts and relativistic shifts in CI, CII, CIII and CIV
We present an accurate ab initio method of calculating isotope shifts and
relativistic shifts in atomic spectra. We test the method on neutral carbon and
three carbon ions. The relativistic shift of carbon lines may allow them to be
included in analyses of quasar absorption spectra that seek to measure possible
variations in the fine structure constant, alpha, over the lifetime of the
Universe. Carbon isotope shifts can be used to measure isotope abundances in
gas clouds: isotope abundances are potentially an important source of
systematic error in the alpha-variation studies. These abundances are also
needed to study nuclear reactions in stars and supernovae, and test models of
chemical evolution of the Universe
Fermi acceleration in time-dependent rectangular billiards due to multiple passages through resonances
We consider a slowly rotating rectangular billiard with moving boundaries and
use the canonical perturbation theory to describe the dynamics of a billiard
particle. In the process of slow evolution certain resonance conditions can be
satisfied. Correspondingly, phenomena of scattering on a resonance and capture
into a resonance happen in the system. These phenomena lead to destruction of
adiabatic invariance and to unlimited acceleration of the particle.Comment: 20 pages. Presented on School-Conference "Mathematics and Physics of
Billiard-Like Systems" (Ubatuba, 2011). Accepted to Chao
Using Molecules to Measure Nuclear Spin-Dependent Parity Violation
Nuclear spin-dependent parity violation arises from weak interactions between
electrons and nucleons, and from nuclear anapole moments. We outline a method
to measure such effects, using a Stark-interference technique to determine the
mixing between opposite-parity rotational/hyperfine levels of ground-state
molecules. The technique is applicable to nuclei over a wide range of atomic
number, in diatomic species that are theoretically tractable for
interpretation. This should provide data on anapole moments of many nuclei, and
on previously unmeasured neutral weak couplings
Constants of Geodesic Motion in Higher-Dimensional Black-Hole Spacetimes
In [arXiv:hep-th/0611083] we announced the complete integrability of geodesic
motion in the general higher-dimensional rotating black-hole spacetimes. In the
present paper we prove all the necessary steps leading to this conclusion. In
particular, we demonstrate the independence of the constants of motion and the
fact that they Poisson commute. The relation to a different set of constants of
motion constructed in [arXiv:hep-th/0612029] is also briefly discussed.Comment: 8 pages, no figure
Complete Integrability of Geodesic Motion in General Kerr-NUT-AdS Spacetimes
We explicitly exhibit n-1 constants of motion for geodesics in the general
D-dimensional Kerr-NUT-AdS rotating black hole spacetime, arising from
contractions of even powers of the 2-form obtained by contracting the geodesic
velocity with the dual of the contraction of the velocity with the
(D-2)-dimensional Killing-Yano tensor. These constants of motion are
functionally independent of each other and of the D-n+1 constants of motion
that arise from the metric and the D-n = [(D+1)/2] Killing vectors, making a
total of D independent constants of motion in all dimensions D. The Poisson
brackets of all pairs of these D constants are zero, so geodesic motion in
these spacetimes is completely integrable.Comment: 4 pages. We have now found that the geodesic motion is not just
integrable, but completely integrabl
The Bose-Einstein correlation function from a Quantum Field Theory point of view
We show that a recently proposed derivation of Bose-Einstein correlations
(BEC) by means of a specific version of thermal Quantum Field Theory (QFT),
supplemented by operator-field evolution of the Langevin type, allows for a
deeper understanding of the possible coherent behaviour of the emitting source
and a clear identification of the origin of the observed shape of the BEC
function . Previous conjectures in this matter obtained by other
approaches are confirmed and have received complementary explanation.Comment: Some misprints corrected. To be publishe in Phys. Rev.
Some forgotten features of the Bose Einstein Correlations
Notwithstanding the visible maturity of the subject of Bose-Einstein
Correlations (BEC), as witnessed nowadays, we would like to bring to ones
attention two points, which apparently did not received attention they deserve:
the problem of the choice of the form of correlation function when
effects of partial coherence of the hadronizing source are to be included and
the feasibility to model effects of Bose-Einstein statistics, in particular the
BEC, by direct numerical simulations.Comment: Talk delivered by G.Wilk at the International Workshop {\it
Relativistic Nuclear Physics: from Nuclotron to LHC energies}, Kiev, June
18-22, 2007, Ukraine; misprints correcte
Optics of spin-noise-induced gyrotropy of asymmetric microcavity
The optical gyrotropy noise of a high-finesse semiconductor Bragg microcavity
with an embedded quantum well (QW) is studied at different detunings of the
photon mode and the QW exciton resonances. A strong suppression of the noise
magnitude for the photon mode frequencies lying above exciton resonances is
found. We show that such a critical behavior of the observed optical noise
power is specific of asymmetric Fabry-Perot resonators. As follows from our
analysis, at a certain level of intracavity loss, the reflectivity of the
asymmetric resonator vanishes, while the polarimetric sensitivity to the
gyrotropy changes dramatically when moving across the critical point. The
results of model calculations are in a good agreement with our experimental
data on the spin noise in a single-quantum-well microcavity and are confirmed
also by the spectra of the photo-induced Kerr rotation in the pump-probe
experiments.Comment: 6 pages, 5 figure
- …