1,165,608 research outputs found
Bound States in n Dimensions (Especially n = 1 and n = 2)
We stress that in contradiction with what happens in space dimensions , there is no strict bound on the number of bound states with the same
structure as the semi-classical estimate for large coupling constant and give,
in two dimensions, examples of weak potentials with one or infinitely many
bound states. We derive bounds for one and two dimensions which have the
"right" coupling constant behaviour for large coupling.Comment: Talk given by A. Martin at Les Houches, October 2001, to appear in
"Few-Body Problems
Algebraic Integration of Sigma Model Field Equations
We prove that the dualization algebra of the symmetric space coset sigma
model is a Lie algebra and we show that it generates an appropriate adjoint
representation which enables the local integration of the field equations
yielding the first-order ones.Comment: 27p
Analysis of Velocity Derivatives in Turbulence based on Generalized Statistics
A theoretical formula for the probability density function (PDF) of velocity
derivatives in a fully developed turbulent flow is derived with the
multifractal aspect based on the generalized measures of entropy, i.e., the
extensive Renyi entropy or the non-extensive Tsallis entropy, and is used,
successfully, to analyze the PDF's observed in the direct numerical simulation
(DNS) conducted by Gotoh et al.. The minimum length scale r_d/eta in the
longitudinal (transverse) inertial range of the DNS is estimated to be
r_d^L/eta = 1.716 (r_d^T/eta = 2.180) in the unit of the Kolmogorov scale eta.Comment: 6 pages, 1 figur
Magnetic and Electronic Phase Diagram and Superconductivity in the Organic Superconductors k-(BEDT-TTF)2X
The magnetic susceptibility of the organic superconductors -(h8 or
d8-ET), Cu(NCS) and Cu[N(CN)]Br has been studied. A
metallic phase below 37 38 K for Cu[N(CN)]Br and
46 50 K for Cu(NCS) has an anisotropic temperature
dependence of the susceptibility and the charge transport. Partial
charge-density-wave or charge fluctuation is expected to coexist with the
metallic phase instead of the large antiferromagnetic fluctuation above
. The phase diagram and the superconductivity of -(ET)
are discussed in connection with this phase.Comment: 5 pages, 4figures, REVTeX, references are corrected, accepted for
pubication in Phys. Rev.
Decay of nuclear hyperpolarization in silicon microparticles
We investigate the low-field relaxation of nuclear hyperpolarization in
undoped and highly doped silicon microparticles at room temperature following
removal from high field. For nominally undoped particles, two relaxation time
scales are identified for ambient fields above 0.2 mT. The slower, T_1s, is
roughly independent of ambient field; the faster, T_1f, decreases with
increasing ambient field. A model in which nuclear spin relaxation occurs at
the particle surface via a two-electron mechanism is shown to be in good
agreement with the experimental data, particularly the field-independence of
T_1s. For boron-doped particles, a single relaxation time scale is observed.
This suggests that for doped particles, mobile carriers and bulk ionized
acceptor sites, rather than paramagnetic surface states, are the dominant
relaxation mechanisms. Relaxation times for the undoped particles are not
affected by tumbling in a liquid solution.Comment: related papers at http://marcuslab.harvard.ed
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