6,717 research outputs found
Higher Order Approximation to the Hill Problem Dynamics about the Libration Points
An analytical solution to the Hill problem Hamiltonian expanded about the
libration points has been obtained by means of perturbation techniques. In
order to compute the higher orders of the perturbation solution that are needed
to capture all the relevant periodic orbits originated from the libration
points within a reasonable accuracy, the normalization is approached in complex
variables. The validity of the solution extends to energy values considerably
far away from that of the libration points and, therefore, can be used in the
computation of Halo orbits as an alternative to the classical
Lindstedt-Poincar\'e approach. Furthermore, the theory correctly predicts the
existence of the two-lane bridge of periodic orbits linking the families of
planar and vertical Lyapunov orbits.Comment: 28 pages, 8 figure
Theory of integer quantum Hall polaritons in graphene
We present a theory of the cavity quantum electrodynamics of the graphene
cyclotron resonance. By employing a canonical transformation, we derive an
effective Hamiltonian for the system comprised of two neighboring Landau levels
dressed by the cavity electromagnetic field (integer quantum Hall polaritons).
This generalized Dicke Hamiltonian, which contains terms that are quadratic in
the electromagnetic field and respects gauge invariance, is then used to
calculate thermodynamic properties of the quantum Hall polariton system.
Finally, we demonstrate that the generalized Dicke description fails when the
graphene sheet is heavily doped, i.e. when the Landau level spectrum of 2D
massless Dirac fermions is approximately harmonic. In this case we `integrate
out' the Landau levels in valence band and obtain an effective Hamiltonian for
the entire stack of Landau levels in conduction band, as dressed by strong
light-matter interactions.Comment: 20 pages, 7 figure
4e-condensation in a fully frustrated Josephson junction diamond chain
Fully frustrated one-dimensional diamond Josephson chains have been shown [B.
Dou\c{c}ot and J. Vidal, Phys. Rev. Lett. {\bf 88}, 227005 (2002)] to posses a
remarkable property: The superfluid phase occurs through the condensation of
pairs of Cooper pairs. By means of Monte Carlo simulations we analyze
quantitatively the Insulator to -Superfluid transition. We determine the
location of the critical point and discuss the behaviour of the phase-phase
correlators. For comparison we also present the case of a diamond chain at zero
and 1/3 frustration where the standard -condensation is observed.Comment: 5 pages, 7 figure
Non-adiabatic effects in long-pulse mixed-field orientation of a linear polar molecule
We present a theoretical study of the impact of an electrostatic field
combined with non-resonant linearly polarized laser pulses on the rotational
dynamics of linear molecules. Within the rigid rotor approximation, we solve
the time-dependent Schr\"odinger equation for several field configurations.
Using the OCS molecule as prototype, the field-dressed dynamics is analyzed in
detail for experimentally accessible static field strengths and laser pulses.
Results for directional cosines are presented and compared to the predictions
of the adiabatic theory. We demonstrate that for prototypical field
configuration used in current mixed-field orientation experiments, the
molecular field dynamics is, in general, non-adiabatic, being mandatory a
time-dependent description of these systems. We investigate several field
regimes identifying the sources of non-adiabatic effects, and provide the field
parameters under which the adiabatic dynamics would be achieved.Comment: 16 pages, 16 figures. Submitted to Physical Review
Double-Peaked Narrow-Line Active Galactic Nuclei. II. The Case Of Equal Peaks
Active galactic nuclei (AGNs) with double-peaked narrow lines (DPAGNs) may be caused by kiloparsec-scale binary AGNs, bipolar outflows, or rotating gaseous disks. We examine the class of DPAGNs in which the two narrow-line components have closely similar intensity as being especially likely to involve disks or jets. Two spectroscopic indicators support this likelihood. For DPAGNs from Smith et al., the "equal-peaked" objects (EPAGNs) have [Ne V]/[O III] ratios lower than for a control sample of non-double-peaked AGNs. This is unexpected for a pair of normal AGNs in a galactic merger, but may be consistent with [O III] emission from a rotating ring with relatively little gas at small radii. Also, [O III]/H beta ratios of the redshifted and blueshifted systems in the EPAGN are more similar to each other than in a control sample, suggestive of a single ionizing source and inconsistent with the binary interpretation.University Cooperative Society of the University of Texas at AustinJane and Roland Blumberg Cenntenial Professorship in AstronomyAlfred P. Sloan FoundationNational Aeronautics and Space AdministrationNational Science FoundationU.S. Department of EnergyJapanese MonbukagakushoMax Planck SocietyUniversity of ChicagoInstitute for Advanced StudyJapan Participation GroupJohns Hopkins UniversityKorean Scientist GroupLos Alamos National LaboratoryMax-Planck-Institute for Astronomy (MPIA)Max-Planck-Institute for Astrophysics (MPA)New Mexico State UniversityUniversity of PittsburghUniversity of PortsmouthPrinceton UniversityUnited States Naval ObservatoryUniversity of WashingtonFermilabAstronom
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