21,040 research outputs found
On the extra phase correction to the semiclassical spin coherent-state propagator
The problem of an origin of the Solary-Kochetov extra-phase contribution to
the naive semiclassical form of a generalized phase-space propagator is
addressed with the special reference to the su(2) spin case which is the most
important in applications. While the extra-phase correction to a flat
phase-space propagator can straightforwardly be shown to appear as a difference
between the principal and the Weyl symbols of a Hamiltonian in the
next-to-leading order expansion in the semiclassical parameter, the same
statement for the semiclassical spin coherent-state propagator holds provided
the Holstein-Primakoff representation of the su(2) algebra generators is
employed.Comment: 19 pages, no figures; a more general treatment is presented, some
references are added, title is slightly changed; submitted to JM
Antarctic meteorite newsletter. Volume 4: Number 1, February 1981: Antarctic meteorite descriptions, 1976, 1977, 1978, 1979
This issue of the Newsletter is essentially a catalog of all antarctic meteorites in the collections of the Johnson Space Center Curation Facility and the Smithsonian except for 288 pebbles now being classed. It includes listings of all previously distributed data sheets plus a number of new ones for 1979. Indexes of samples include meteorite name/number, classification, and weathering category. Separate indexes list type 3 and 4 chondrites, all irons, all achondrites, and all carbonaceous chondrites
Fast drift kilometric radio bursts and solar proton events
Initial results of a comparative study of major fast drift kilometric bursts and solar proton events from Sep. 1978 to Feb. 1983 are presented. It was found that only about half of all intense, long duration ( 40 min above 500 sfu) 1 MHz bursts can be associated with F 20 MeV proton events. However, for the subset of such fast drift bursts accompanied by metric Type 2 and/or 4 activity (approximately 40% of the total), the degree of association with 20 MeV events is 80%. For the reverse association, it was found that proton events with J( 20 MeV) 0.01 1 pr cm(-2)s(-1)sr(-1)MeV(-1) were typically (approximately 80% of the time) preceded by intense 1 MHz bursts that exceeded the 500 sfu level for times 20 min (median duration approximately 35 min)
Radial Velocity along the Voyager 1 Trajectory: The Effect of Solar Cycle
As Voyager 1 and Voyager 2 are approaching the heliopause (HP)—the boundary between the solar wind (SW) and the local interstellar medium (LISM)—we expect new, unknown features of the heliospheric interface to be revealed. A seeming puzzle reported recently by Krimigis et al. concerns the unusually low, even negative, radial velocity components derived from the energetic ion distribution. Steady-state plasma models of the inner heliosheath (IHS) show that the radial velocity should not be equal to zero even at the surface of the HP. Here we demonstrate that the velocity distributions observed by Voyager 1 are consistent with time-dependent simulations of the SW-LISM interaction. In this Letter, we analyze the results from a numerical model of the large-scale heliosphere that includes solar cycle effects. Our simulations show that prolonged periods of low to negative radial velocity can exist in the IHS at substantial distances from the HP. It is also shown that Voyager 1 was more likely to observe such regions than Voyager 2
Fusion products, Kostka polynomials, and fermionic characters of su(r+1)_k
Using a form factor approach, we define and compute the character of the
fusion product of rectangular representations of \hat{su}(r+1). This character
decomposes into a sum of characters of irreducible representations, but with
q-dependent coefficients. We identify these coefficients as (generalized)
Kostka polynomials. Using this result, we obtain a formula for the characters
of arbitrary integrable highest-weight representations of \hat{su}(r+1) in
terms of the fermionic characters of the rectangular highest weight
representations.Comment: 21 pages; minor changes, typos correcte
Microscopic construction of the chiral Luttinger liquid theory of the quantum Hall edge
We give a microscopic derivation of the chiral Luttinger liquid theory for
the Laughlin states. Starting from the wave function describing an arbitrary
incompressibly deformed Laughlin state (IDLS) we quantize these deformations.
In this way we obtain the low-energy projections of local microscopic operators
and derive the quantum field theory of edge excitations directly from quantum
mechanics of electrons. This shows that to describe experimental and numeric
deviations from chiral Luttinger liquid theory one needs to go beyond
Laughlin's approximation. We show that in the large N limit the IDLS is
described by the dispersionless Toda hierarchy.Comment: 5 pages, revtex, several clarifying comments adde
The string model of the Cooper pair in the anisotropic superconductor
The analogy between the Cooper pair in high temperature superconductor and
the quark-antiquark pair in quantum chromodynamics (QCD) is proposed. In QCD
the nonlinear chromodynamical field between a quark and an antiquark is
confined to a tube. So we assume that there is the strong interaction between
phonons which can confine them to some tube too. This tube is described using
the nonlinear Schr\"odinger equation. We show that it has an infinite spectrum
of axially symmetric (string) solutions with negative finite linear energy
density. The one-dimensional nonlinear Schr\"odinger equation has a finite
spectrum (hence, it has a steady-state) which describes the Cooper pair
squezeed between anisotropy planes in the superconductor. It is shown that in
this model the transition temperature is approximately 45 K.Comment: final version, Latex, 9p, to be published in Phys. Rev.
Spectral Evolution of Anomalous Cosmic Rays at Voyager 1 beyond the Termination Shock
When the Voyager 1 spacecraft crossed the termination shock (TS) on 2004 December 16, the energy spectra of anomalous cosmic rays (ACRs) could not have been produced by steady-state diffusive shock acceleration. However, over the next few years, in the declining phase of the solar cycle, the spectra began to evolve into the expected power-law profile. Observations at the shock led to a broad range of alternative theories for ACR acceleration. In spite of that, in this work we show that the observations could be explained by assuming ACRs are accelerated at the TS. In this paper, we propose that the solar cycle had an important effect on the unrolling of the spectra in the heliosheath. To investigate the spectral evolution of ACRs, a magnetohydrodynamic background model with stationary solar-wind inner boundary conditions was used to model the transport of helium and oxygen ions. We used a backward-in-time stochastic integration technique where phase-space trajectories are integrated until the so-called "injection energy" is reached. Our simulation results were compared with Voyager 1 observations using three different diffusion models. It is shown that the spectral evolution of ACRs in the heliosheath at Voyager 1 could be explained by an increase in the source strength and an enhancement in diffusion as a result of a decrease of the turbulent correlation length in the declining phase of the solar cycle. At the same time, drift effects seem to have had a smaller effect on the evolution of the spectra
Dispersion interactions and reactive collisions of ultracold polar molecules
Progress in ultracold experiments with polar molecules requires a clear
understanding of their interactions and reactivity at ultra-low collisional
energies. Two important theoretical steps in this process are the
characterization of interaction potentials between molecules and the modeling
of reactive scattering mechanism. Here, we report on the {\it abinitio}
calculation of isotropic and anisotropic van der Waals interaction potentials
for polar KRb and RbCs colliding with each other or with ultracold atoms. Based
on these potentials and two short-range scattering parameters we then develop a
single-channel scattering model with flexible boundary conditions. Our
calculations show that at low temperatures (and in absence of an external
electric field) the reaction rates between molecules or molecules with atoms
have a resonant character as a function of the short-range parameters. We also
find that both the isotropic and anisotropic van der Waals coefficients have
significant contributions from dipole coupling to excited electronic states.
Their values can differ dramatically from those solely obtained from the
permanent dipole moment. A comparison with recently obtained reaction rates of
fermionic KRb shows that the experimental data can not be
explained by a model where the short-range scattering parameters are
independent of the relative orbital angular momentum or partial wave.Comment: 15 pages, 12 figure
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