13,662 research outputs found
On the Integrability, B\"Acklund Transformation and Symmetry Aspects of a Generalized Fisher Type Nonlinear Reaction-Diffusion Equation
The dynamics of nonlinear reaction-diffusion systems is dominated by the
onset of patterns and Fisher equation is considered to be a prototype of such
diffusive equations. Here we investigate the integrability properties of a
generalized Fisher equation in both (1+1) and (2+1) dimensions. A Painlev\'e
singularity structure analysis singles out a special case () as
integrable. More interestingly, a B\"acklund transformation is shown to give
rise to a linearizing transformation for the integrable case. A Lie symmetry
analysis again separates out the same case as the integrable one and
hence we report several physically interesting solutions via similarity
reductions. Thus we give a group theoretical interpretation for the system
under study. Explicit and numerical solutions for specific cases of
nonintegrable systems are also given. In particular, the system is found to
exhibit different types of travelling wave solutions and patterns, static
structures and localized structures. Besides the Lie symmetry analysis,
nonclassical and generalized conditional symmetry analysis are also carried
out.Comment: 30 pages, 10 figures, to appear in Int. J. Bifur. Chaos (2004
Production rates for hadrons, pentaquarks and , and di-baryon in relativistic heavy ion collisions by a quark combination model
The hadron production in relativistic heavy ion collisions is well described
by the quark combination model. The mixed ratios for various hadrons and the
transverse momentum spectra for long-life hadrons are predicted and agree with
recent RHIC data. The production rates for the pentaquarks , and the di-baryon are estimated, neglecting
the effect from the transition amplitude for constituent quarks to form an
exotic state.Comment: The difference between our model and other combination models is
clarified. The scaled transverse momentum spectra for pions, kaons and
protoms at both 130 AGeV and 200 AGeV are given, replacing the previous
results in transverse momentum spectr
Supra-oscillatory critical temperature dependence of Nb-Ho bilayers
We investigate the critical temperature Tc of a thin s-wave superconductor
(Nb) proximity coupled to a helical rare earth ferromagnet (Ho). As a function
of the Ho layer thickness, we observe multiple oscillations of Tc superimposed
on a slow decay, that we attribute to the influence of the Ho on the Nb
proximity effect. Because of Ho inhomogeneous magnetization, singlet and
triplet pair correlations are present in the bilayers. We take both into
consideration when solving the self consistent Bogoliubov-de Gennes equations,
and we observe a reasonable agreement. We also observe non-trivial transitions
into the superconducting state, the zero resistance state being attained after
two successive transitions which appear to be associated with the magnetic
structure of Ho.Comment: Main article: 5 pages, 4 figures; Supplementary materials: 4 pages, 5
figure
Bosonic Super Liouville System: Lax Pair and Solution
We study the bosonic super Liouville system which is a statistical
transmutation of super Liouville system. Lax pair for the bosonic super
Liouville system is constructed using prolongation method, ensuring the Lax
integrability, and the solution to the equations of motion is also considered
via Leznov-Saveliev analysis.Comment: LaTeX, no figures, 11 page
Color separate singlets in annihilation
We use the method of color effective Hamiltonian to study the properties of
states in which a gluonic subsystem forms a color singlet, and we will study
the possibility that such a subsystem hadronizes as a separate unit. A parton
system can normally be subdivided into singlet subsystems in many different
ways, and one problem arises from the fact that the corresponding states are
not orthogonal. We show that if only contributions of order are
included, the problem is greatly simplified. Only a very limited number of
states are possible, and we present an orthogonalization procedure for these
states. The result is simple and intuitive and could give an estimate of the
possibility to produce color separated gluonic subsystems, if no dynamical
effects are important. We also study with a simple MC the possibility that
configurations which correspond to "short strings" are dynamically favored. The
advantage of our approach over more elaborate models is its simplicity, which
makes it easier to estimate color reconnection effects in reactions which are
more complicated than the relatively simple annihilation.Comment: Revtex, 24 pages, 7 figures; Compared to the previous version, 1 new
figure is added and Monte-Carlo results are re-analyzed, as suggested by the
referee; To appear in Phys. Rev.
X-ray Spectral and timing properties of the black hole x-ray transient Swift J1753.5-0127
We have carried out detailed analysis on the black hole candidate (BHC) X-
ray transient Swift J1753.5-0127 observed by the Rossi X-Ray Timing Explorer
(RXTE) during its outburst in 2005 {2006. The spectral analysis shows that the
emissions are dominated by the hard X-rays, thus revealing the low/hard state
of the source during the outburst. The peak luminosity is found lower than the
typical value of balancing the mass flow and evaporation of the inner edge of
disk (Meyer-Hofmeister 2004). As a result, the disk is prevented from extending
inward to produce strong soft X-rays, corresponding to the so-called high/soft
state. These are the typical characteristics for a small subset of BHCs, i.e.
those soft X-ray transients stay at the low/hard state during the outburst. In
most observational time, the QPO frequencies are found to vary roughly linearly
with the fluxes and the spectral indices, while the deviation from this
relationship at the peak luminosity might provide the first observational
evidence of a partially evaporated inner edge of the accretion disk. The
anti-correlation between the QPO frequency and spectral color suggests that the
global disk oscillation model proposed by Titarchuk & Osherovich (2000) is not
likely at work.Comment: Accepted by ApJ, 24 pages, 13 figures, 3 table
Optimal Principal Component Analysis in Distributed and Streaming Models
We study the Principal Component Analysis (PCA) problem in the distributed
and streaming models of computation. Given a matrix a
rank parameter , and an accuracy parameter , we
want to output an orthonormal matrix for which where is the best rank- approximation to .
This paper provides improved algorithms for distributed PCA and streaming
PCA.Comment: STOC2016 full versio
Study of color connections in annihilation
We replace in the event generator JETSET the color singlet chain connection
with the color separate state one as the interface between the hard and soft
sectors of hadronic processes. The modified generator is applied to produce the
hadronic events in annihilation. It describes the experimental data
at the same level as the original JETSET with default parameters. This should
be understood as a demonstration that color singlet chain is not the unique
color connection. We also search for the difference in special sets of
three-jet events arising from different color connections, which could subject
to further experimental test.Comment: 23 pages, 8 figures, 4 tables, Revtex
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