1,028 research outputs found
Free motion on the Poisson SU(n) group
SL(N,C) is the phase space of the Poisson SU(N). We calculate explicitly the
symplectic structure of SL(N,C), define an analogue of the Hamiltonian of the
free motion on SU(N) and solve the corresponding equations of motion. Velocity
is related to the momentum by a non-linear Legendre transformation.Comment: LaTeX, 10 page
Phase spaces related to standard classical -matrices
Fundamental representations of real simple Poisson Lie groups are Poisson
actions with a suitable choice of the Poisson structure on the underlying
(real) vector space. We study these (mostly quadratic) Poisson structures and
corresponding phase spaces (symplectic groupoids).Comment: 20 pages, LaTeX, no figure
Mean field dynamics of superfluid-insulator phase transition in a gas of ultra cold atoms
A large scale dynamical simulation of the superfluid to Mott insulator
transition in the gas of ultra cold atoms placed in an optical lattice is
performed using the time dependent Gutzwiller mean field approach. This
approximate treatment allows us to take into account most of the details of the
recent experiment [Nature 415, 39 (2002)] where by changing the depth of the
lattice potential an adiabatic transition from a superfluid to a Mott insulator
state has been reported. Our simulations reveal a significant excitation of the
system with a transition to insulator in restricted regions of the trap.Comment: final version, correct Fig.7 (the published version contains wrong
fig.7 by mistake
The Mott insulator phase of the one dimensional Bose-Hubbard model: a high order perturbative study
The one dimensional Bose-Hubbard model at a unit filling factor is studied by
means of a very high order symbolic perturbative expansion. Analytical
expressions are derived for the ground state quantities such as energy per
site, variance of on-site occupation, and different correlation functions.
These findings are compared to numerics and good agreement is found in the Mott
insulator phase. Our results provide analytical approximations to important
observables in the Mott phase, and are also of direct relevance to future
experiments with ultra cold atomic gases placed in optical lattices. We also
discuss the symmetry of the Bose-Hubbard model associated with the sign change
of the tunneling coupling.Comment: 7 pages, 4 figures, 1 table. Significantly expanded version with
respect to former submission (to appear in Phys. Rev. A
Double ionization of a three-electron atom: Spin correlation effects
We study the effects of spin degrees of freedom and wave function symmetries
on double ionization in three-electron systems. Each electron is assigned one
spatial degree of freedom. The resulting three-dimensional Schr\"odinger
equation is integrated numerically using grid-based Fourier transforms. We
reveal three-electron effects on the double ionization yield by comparing
signals for different ionization channels. We explain our findings by the
existence of fundamental differences between three-electronic and truly
two-electronic spin-resolved ionization schemes. We find, for instance, that
double ionization from a three-electron system is dominated by electrons that
have the opposite spin
Spontaneous emission of non-dispersive Rydberg wave packets
Non dispersive electronic Rydberg wave packets may be created in atoms
illuminated by a microwave field of circular polarization. We discuss the
spontaneous emission from such states and show that the elastic incoherent
component (occuring at the frequency of the driving field) dominates the
spectrum in the semiclassical limit, contrary to earlier predictions. We
calculate the frequencies of single photon emissions and the associated rates
in the "harmonic approximation", i.e. when the wave packet has approximately a
Gaussian shape. The results agree well with exact quantum mechanical
calculations, which validates the analytical approach.Comment: 14 pages, 4 figure
Photometric, Spectroscopic and Orbital Period Study of Three Early Type Semi-detached Systems: XZ Aql, UX Her and AT Peg
In this paper we present a combined photometric, spectroscopic and orbital
period study of three early-type eclipsing binary systems: XZ Aql, UX Her, and
AT Peg. As a result, we have derived the absolute parameters of their
components and, on that basis, we discuss their evolutionary states.
Furthermore, we compare their parameters with those of other binary systems and
with the theoretical models. An analysis of all available up-to-date times of
minima indicated that all three systems studied here show cyclic orbital
changes, their origin is discussed in detail. Finally, we performed a frequency
analysis for possible pulsational behavior and as a result we suggest that XZ
Aql hosts a {\delta} Scuti component.Comment: 40 pages, 16 figure
The Absolute Parameters of The Detached Eclipsing Binary V482 Per
We present the results of the spectroscopic, photometric and orbital period
variation analyses of the detached eclipsing binary \astrobj{V482~Per}. We
derived the absolute parameters of the system (M = 1.51 M,
M = 1.29 M, R = 2.39 R, R = 1.45
R, L = 10.15 L, L = 3.01 L) for the
first time in literature, based on an analysis of our own photometric and
spectroscopic observations. We confirm the nature of the variations observed in
the system's orbital period, suggested to be periodic by earlier works. A light
time effect due to a physically bound, star-sized companion (M = 2.14
M) on a highly eccentric (e = 0.83) orbit, seems to be the most
likely cause. We argue that the companion can not be a single star but another
binary instead. We calculated the evolutionary states of the system's
components, and we found that the primary is slightly evolving after the Main
Sequence, while the less massive secondary lies well inside it.Comment: Published in New Astronomy, Vol. 41, p. 42-4
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