92,063 research outputs found
Deviation of light curves of gamma-ray burst pulses from standard forms due to the curvature effect of spherical fireballs or uniform jets
As revealed previously, under the assumption that some pulses of gamma-ray
bursts are produced by shocks in spherical fireballs or uniform jets of large
opening angles, there exists a standard decay form of the profile of pulses
arising from very narrow or suddenly dimming local (or intrinsic) pulses due to
the relativistic curvature effect (the Doppler effect over the spherical shell
surface). Profiles of pulses arising from other local pulses were previously
found to possess a reverse S-feature deviation from the standard decay form. We
show in this paper that, in addition to the standard decay form shown in Qin et
al. (2004), there exists a marginal decay curve associated with a local
function pulse with a mono-color radiation. We employ the sample of
Kocevski et al. (2003) to check this prediction and find that the phenomenon of
the reverse S-feature is common, when compared with both the standard decay
form and the marginal decay curve. We accordingly propose to take the marginal
decay curve (whose function is simple) as a criteria to check if an observed
pulse could be taken as a candidate suffered from the curvature effect. We
introduce two quantities and to describe the mentioned deviations
within and beyond the position of the decay phase, respectively. The
values of and of pulses of the sample are calculated, and the
result suggests that for most of these pulses their corresponding local pulses
might contain a long decay time relative to the time scale of the curvature
effect.Comment: 24 pages, 7 figures, 1 table accepted for publication in MNRA
An equitriangular integral transform and its applications
Equitriangular integral transform for solving boundary value problems in viscous flow and heat transfe
Phenomenological Analysis of and Elastic Scattering Data in the Impact Parameter Space
We use an almost model-independent analytical parameterization for and
elastic scattering data to analyze the eikonal, profile, and
inelastic overlap functions in the impact parameter space. Error propagation in
the fit parameters allows estimations of uncertainty regions, improving the
geometrical description of the hadron-hadron interaction. Several predictions
are shown and, in particular, the prediction for inelastic overlap
function at TeV shows the saturation of the Froissart-Martin
bound at LHC energies.Comment: 15 pages, 16 figure
A Three-Dimensional Solution of Flows over Wings with Leading-Edge Vortex Separation. Part 2: Program Description Document
For abstract, see N75-32026
Euler equation of the optimal trajectory for the fastest magnetization reversal of nano-magnetic structures
Based on the modified Landau-Lifshitz-Gilbert equation for an arbitrary
Stoner particle under an external magnetic field and a spin-polarized electric
current, differential equations for the optimal reversal trajectory, along
which the magnetization reversal is the fastest one among all possible reversal
routes, are obtained. We show that this is a Euler-Lagrange problem with
constrains. The Euler equation of the optimal trajectory is useful in designing
a magnetic field pulse and/or a polarized electric current pulse in
magnetization reversal for two reasons. 1) It is straightforward to obtain the
solution of the Euler equation, at least numerically, for a given magnetic
nano-structure characterized by its magnetic anisotropy energy. 2) After
obtaining the optimal reversal trajectory for a given magnetic nano-structure,
finding a proper field/current pulse is an algebraic problem instead of the
original nonlinear differential equation
Film-stability in a vertical rotating tube with a core-gas flow
Linear hydrodynamic stability of interface between Newtonian liquid film and core fluid under influence of swirl, core flow, and gravit
On the relationship of the scaled phase space and Skyrme-coherent state treatments of proton antiproton annihilation at rest
We discuss pion multiplicities and single pion momentum spectra from proton
antiproton annihilation at rest. Both the scaled phase space model and the
Skyrme-coherent state approach describe these observables well. In the coherent
state approach the puzzling size of the scale parameter relating the phase
space integrals for different multiplicities is replaced by a well defined
weight function. The strength of this function is determined by the intensity
of the classical pion field and its spatial extent is of order 1 fm.Comment: 11 pages including 4 figures(postscript
Space group symmetry fractionalization in a chiral kagome Heisenberg antiferromagnet
The anyonic excitations of a spin-liquid can feature fractional quantum
numbers under space-group symmetries. Detecting these fractional quantum
numbers, which are analogs of the fractional charge of Laughlin quasiparticles,
may prove easier than the direct observation of anyonic braiding and
statistics. Motivated by the recent numerical discovery of spin-liquid phases
in the kagome Heisenberg antiferromagnet, we theoretically predict the pattern
of space group symmetry fractionalization in the kagome lattice chiral spin
liquid. We provide a method to detect these fractional quantum numbers in
finite-size numerics which is simple to implement in DMRG. Applying these
developments to the chiral spin liquid phase of a kagome Heisenberg model, we
find perfect agreement between our theoretical prediction and numerical
observations.Comment: 5 pages plus appendi
- …