2,747 research outputs found
New reductions of integrable matrix PDEs: -invariant systems
We propose a new type of reduction for integrable systems of coupled matrix
PDEs; this reduction equates one matrix variable with the transposition of
another multiplied by an antisymmetric constant matrix. Via this reduction, we
obtain a new integrable system of coupled derivative mKdV equations and a new
integrable variant of the massive Thirring model, in addition to the already
known systems. We also discuss integrable semi-discretizations of the obtained
systems and present new soliton solutions to both continuous and semi-discrete
systems. As a by-product, a new integrable semi-discretization of the Manakov
model (self-focusing vector NLS equation) is obtained.Comment: 33 pages; (v4) to appear in JMP; This paper states clearly that the
elementary function solutions of (a vector/matrix generalization of) the
derivative NLS equation can be expressed as the partial -derivatives of
elementary functions. Explicit soliton solutions are given in the author's
talks at http://poisson.ms.u-tokyo.ac.jp/~tsuchida
A Maximum Mass-to-Size Ratio in Scalar-Tensor Theories of Gravity
We derive a modified Buchdahl inequality for scalar-tensor theories of
gravity. In general relativity, Buchdahl has shown that the maximum value of
the mass-to-size ratio, , is 8/9 for static and spherically symmetric
stars under some physically reasonable assumptions. We formally apply
Buchdahl's method to scalar-tensor theories and obtain theory-independent
inequalities. After discussing the mass definition in scalar-tensor theories,
these inequalities are related to a theory-dependent maximum mass-to-size
ratio. We show that its value can exceed not only Buchdahl's limit, 8/9, but
also unity, which we call {\it the black hole limit}, in contrast to general
relativity. Next, we numerically examine the validity of the assumptions made
in deriving the inequalities and the applicability of our analytic results. We
find that the assumptions are mostly satisfied and that the mass-to-size ratio
exceeds both Buchdahl's limit and the black hole limit. However, we also find
that this ratio never exceeds Buchdahl's limit when we impose the further
condition, , on the density, , and pressure, , of the
matter.Comment: 23 pages, 13 figures and 1 tabl
Exact Analysis of Soliton Dynamics in Spinor Bose-Einstein Condensates
We propose an integrable model of a multicomponent spinor Bose-Einstein
condensate in one dimension, which allows an exact description of the dynamics
of bright solitons with spin degrees of freedom. We consider specifically an
atomic condensate in the F=1 hyperfine state confined by an optical dipole
trap. When the mean-field interaction is attractive (c_0 < 0) and the
spin-exchange interaction of a spinor condensate is ferromagnetic (c_2 < 0), we
prove that the system possesses a completely integrable point leading to the
existence of multiple bright solitons. By applying results from the inverse
scattering method, we analyze a collision law for two-soliton solutions and
find that the dynamics can be explained in terms of the spin precession.Comment: 4 pages, 2 figure
Complete integrability of derivative nonlinear Schr\"{o}dinger-type equations
We study matrix generalizations of derivative nonlinear Schr\"{o}dinger-type
equations, which were shown by Olver and Sokolov to possess a higher symmetry.
We prove that two of them are `C-integrable' and the rest of them are
`S-integrable' in Calogero's terminology.Comment: 14 pages, LaTeX2e (IOP style), to appear in Inverse Problem
Microscopic Evidence for Evolution of Superconductivity by Effective Carrier Doping in Boron-doped Diamond:11B-NMR study
We have investigated the superconductivity discovered in boron (B)-doped
diamonds by means of 11B-NMR on heteroepitaxially grown (111) and (100) films.
11B-NMR spectra for all of the films are identified to arise from the
substitutional B(1) site as single occupation and lower symmetric B(2) site
substituted as boron+hydrogen(B+H) complex, respectively. A clear evidence is
presented that the effective carriers introduced by B(1) substitution are
responsible for the superconductivity, whereas the charge neutral B(2) sites
does not offer the carriers effectively. The result is also corroborated by the
density of states deduced by 1/T1T measurement, indicating that the evolution
of superconductivity is driven by the effective carrier introduced by
substitution at B(1) site.Comment: 4 pages, 6 figures, to be published in Phys. Rev. B (Brief report
The direct synthesis of tertiary amines with three different substituents via the reaction of primary amines, alkyl halides, and alpha-chlorine substituted allylsilanes catalyzed by Lewis acids
ArticleTetrahedron Letters. 46(27): 4527-4530 (2005)journal articl
Erratum
Nighttime temperature treatment of fruit clusters of 'Ald Queen' grapes during maturation and its effects ofn the sldn color and abscisic acid contentVitis 46 (4), 208-209 (2007
Symmetrically coupled higher-order nonlinear Schroedinger equations: singularity analysis and integrability
The integrability of a system of two symmetrically coupled higher-order
nonlinear Schr\"{o}dinger equations with parameter coefficients is tested by
means of the singularity analysis. It is proven that the system passes the
Painlev\'{e} test for integrability only in ten distinct cases, of which two
are new. For one of the new cases, a Lax pair and a multi-field generalization
are obtained; for the other one, the equations of the system are uncoupled by a
nonlinear transformation.Comment: 12 pages, LaTeX2e, IOP style, final version, to appear in
J.Phys.A:Math.Ge
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