3,321 research outputs found
Nuclear pairing at finite temperature and angular momentum
An approach is proposed to nuclear pairing at finite temperature and angular
momentum, which includes the effects of the quasiparticle-number fluctuation
and dynamic coupling to pair vibrations within the self-consistent
quasiparticle random-phase approximation. The numerical calculations of pairing
gaps, total energies, and heat capacities are carried out within a doubly
folded multilevel model as well as several realistic nuclei. The results
obtained show that, in the region of moderate and strong couplings, the sharp
transition between the superconducting and normal phases is smoothed out,
causing a thermal pairing gap, which does not collapse at a critical
temperature predicted by the conventional Bardeen-Cooper-Schrieffer's (BCS)
theory, but has a tail extended to high temperatures. The theory also predicts
the appearance of a thermally assisted pairing in hot rotating nuclei.Comment: 4 pages, 1 figure, To appear in the Proceedings of the First Workshop
on State of the Art in Nuclear Cluster Physics, Strasbourg 13 - 16 May, 200
Pairing effect on the giant dipole resonance width at low temperature
The width of the giant dipole resonance (GDR) at finite temperature T in
Sn-120 is calculated within the Phonon Damping Model including the neutron
thermal pairing gap determined from the modified BCS theory. It is shown that
the effect of thermal pairing causes a smaller GDR width at T below 2 MeV as
compared to the one obtained neglecting pairing. This improves significantly
the agreement between theory and experiment including the most recent data
point at T = 1 MeV.Comment: 8 pages, 5 figures to be published in Physical Review
Dynamics of horizontal-like maps in higher dimension
We study the regularity of the Green currents and of the equilibrium measure
associated to a horizontal-like map in C^k, under a natural assumption on the
dynamical degrees. We estimate the speed of convergence towards the Green
currents, the decay of correlations for the equilibrium measure and the
Lyapounov exponents. We show in particular that the equilibrium measure is
hyperbolic. We also show that the Green currents are the unique invariant
vertical and horizontal positive closed currents. The results apply, in
particular, to Henon-like maps, to regular polynomial automorphisms of C^k and
to their small pertubations.Comment: Dedicated to Professor Gennadi Henkin on the occasion of his 65th
birthday, 37 pages, to appear in Advances in Mat
Analysis of directed flow from three-particle correlations
We present a new method for analysing directed flow, based on a
three-particle azimuthal correlation. It is less biased by nonflow correlations
than two-particle methods, and requires less statistics than four-particle
methods. It is illustrated on NA49 data.Comment: Contribution to Quark Matter 2002, Nantes, July 18-24, 200
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