9,037 research outputs found
Realistic calculations of correlations and final state interaction effects in the A(e,e'p)X process off complex nuclei
A linked cluster expansion for the calculation of ground state observables of
complex nuclei with realistic interactions has been used to calculate the
ground state energy, density and momentum distribution of 16O and 40Ca. Using
the same cluster expansion and the wave function and correlation parameters
obtained from the energy calculation, we have evaluated the semi inclusive
reaction A(e,e'p)X taking final state interaction (FSI) into account by a
Glauber type approach; the comparison between the distorted and undistorted
momentum distributions provides an estimate of the transparency of the nuclear
medium to the propagation of the hit proton. The effect of color transparency
is also included by considering the Finite Formation Time (FFT) that the hit
hadron needs to reach its asymptotic physical state.Comment: 8 pages, Latex, 8 figures, presented at the "2nd International
Conference on Nuclear and Particle Physics with CEBAF at JLab
A new realistic many-body approach for the description of high-energy scattering processes off complex nuclei
A linked cluster expansion for the calculation of ground state observables of
nuclei with realistic interactions has been developed. Using the V8' potential
the ground state energy, density and momentum distribution of complex nuclei
have been calculated and found to be in good agreement with the results
obtained within the Fermi Hyper Netted Chain, and Variational Monte Carlo
approaches. Using the same cluster expansion, with wave function and
correlations parameters fixed from the calculation of the ground-state
observables, various high energy scattering processes off complex nuclei have
been calculated taking final state interaction effects into account by means of
the Glauber multiple scattering series.Comment: 7 pages, 4 figures, presented by M. Alvioli at the "13th
International Conference on Recent Progress in Many-Body Theories", Buenos
Aires - Argentina, 5-9 December 200
Finite formation time effects in inclusive and semi-inclusive electro-disintegration of few-body nuclei
Finite Formation Time (FFT) effects in the exclusive reaction ^4He(e,e'p)^3H
at high values of Q^2 are introduced and discussed. It is shown that the
minimum in the momentum distributions predicted by the Plane Wave Impulse
Approximation (PWIA), which is filled by the Glauber-type Final State
Interaction (FSI), is completely recovered when FFT effects are taken into
account. The semi-inclusive process ^4 He(e,e'p)X is also investigated.Comment: 4 pages, 2 eps figure
Cluster Variation Approach to the Random-Anisotropy Blume-Emery-Griffiths Model
The random--anisotropy Blume--Emery--Griffiths model, which has been proposed
to describe the critical behavior of He--He mixtures in a porous
medium, is studied in the pair approximation of the cluster variation method
extended to disordered systems. Several new features, with respect to mean
field theory, are found, including a rich ground state, a nonzero percolation
threshold, a reentrant coexistence curve and a miscibility gap on the high
He concentration side down to zero temperature. Furthermore, nearest
neighbor correlations are introduced in the random distribution of the
anisotropy, which are shown to be responsible for the raising of the critical
temperature with respect to the pure and uncorrelated random cases and
contribute to the detachment of the coexistence curve from the line.Comment: 14 pages (plain TeX) + 12 figures (PostScript, appended), Preprint
POLFIS-TH.02/9
Inflating Fat Bubbles in Clusters of Galaxies by Precessing Massive Slow Jets
We conduct hydrodynamical numerical simulations and find that precessing
massive slow jets can inflate fat bubbles, i.e., more or less spherical
bubbles, that are attached to the center of clusters of galaxies. To inflate a
fat bubble the jet should precess fast. The precessing angle should be
large, or change over a large range (depending also on other parameters), where is the symmetry
axis. The constraints on the velocity and mass outflow rate are similar to
those on wide jets to inflate fat bubbles. The velocity should be v_j \sim
10^4 \kms, and the mass loss rate of the two jets should be 2 \dot M_j
\simeq 1-50 \dot M_\odot \yr^{-1} . These results, and our results from a
previous paper dealing with slow wide jets, support the claim that a large
fraction of the feedback heating in cooling flow clusters and in the processes
of galaxy formation is done by slow massive jets.Comment: Accepted for publication in MNRA
Comment on ``Quasiparticle Spectra around a Single Vortex in a d-wave Superconductor''
In a recent Letter Morita, Kohmoto and Maki analyzed the structure of
quasiparticle states near a single vortex in a d-wave superconductor using an
approximate version of the Bogoliubov - de Gennes theory. Their principal
result is the existence of a bound state within the core region at finite
energy with full rotational symmetry, which they assert explains the recent
scanning tunneling microscopy results on YBCO single crystals. Here we argue
that the approximation used in this work is fundamentally inadequate for the
description of a d-wave vortex and that the obtained circular symmetry of the
local density of states is an unphysical artifact of this approximation.Comment: 1 page REVTeX, to appear in PR
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