34,022 research outputs found
Decay in the Nambu-Jona-Lasinio Model
We study the decays using the version of
the Nambu-Jona-Lasinio model with the effective nonleptonic weak
interaction. The amplitude is in reasonable agreement with
experimental data. On the other hand, the calculated
amplitudes strongly depend on the mass of the low-lying scalar-isoscalar
meson, and therefore give a strong constraint on the parameters of the
model.Comment: 10 pages, 3 Postscript figures, Talk given at YITP Workshp: From
Hadronic Matter to Quark Matter: Evolving View of Hadronic Matter, Kyoto,
Japan, Oct. 30-Nov. 1, 1994, to be published in Prog. Theor. Phys. Supp
Pattern-recalling processes in quantum Hopfield networks far from saturation
As a mathematical model of associative memories, the Hopfield model was now
well-established and a lot of studies to reveal the pattern-recalling process
have been done from various different approaches. As well-known, a single
neuron is itself an uncertain, noisy unit with a finite unnegligible error in
the input-output relation. To model the situation artificially, a kind of 'heat
bath' that surrounds neurons is introduced. The heat bath, which is a source of
noise, is specified by the 'temperature'. Several studies concerning the
pattern-recalling processes of the Hopfield model governed by the
Glauber-dynamics at finite temperature were already reported. However, we might
extend the 'thermal noise' to the quantum-mechanical variant. In this paper, in
terms of the stochastic process of quantum-mechanical Markov chain Monte Carlo
method (the quantum MCMC), we analytically derive macroscopically deterministic
equations of order parameters such as 'overlap' in a quantum-mechanical variant
of the Hopfield neural networks (let us call "quantum Hopfield model" or
"quantum Hopfield networks"). For the case in which non-extensive number of
patterns are embedded via asymmetric Hebbian connections, namely,
for the number of neuron ('far from saturation'), we evaluate
the recalling processes for one of the built-in patterns under the influence of
quantum-mechanical noise.Comment: 10 pages, 3 figures, using jpconf.cls, Proc. of Statphys-Kolkata VI
Loopy belief propagation and probabilistic image processing
Estimation of hyperparameters by maximization of the marginal likelihood in probabilistic image processing is investigated by using the cluster variation method. The algorithms are substantially equivalent to generalized loopy belief propagation
Electronic structure of CaSrVO: a tale of two energy-scales
We investigate the electronic structure of CaSrVO using
photoemission spectroscopy. Core level spectra establish an electronic phase
separation at the surface, leading to distinctly different surface electronic
structure compared to the bulk. Analysis of the photoemission spectra of this
system allowed us to separate the surface and bulk contributions. These results
help us to understand properties related to two vastly differing energy-scales,
namely the low energy-scale of thermal excitations (~) and the
high-energy scale related to Coulomb and other electronic interactions.Comment: 4 pages and 3 figures. Europhysics Letters (appearing
Geometric Bremsstrahlung in the Early Universe
We discuss photon emission from particles decelerlated by the cosmic
expansion. This can be interpretated as a kind of bremsstrahlung induced by the
Universe geometry. In the high momentum limit its transition probability does
not depend on detailed behavior of the expansion.Comment: 20 pages, No figure
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