74,245 research outputs found
Dynamical study of spinodal decomposition in heavy ion collisions
Nuclei undergo a phase transition in nuclear reactions according to a caloric
curve determined by the amount of entropy. Here, the generation of entropy is
studied in relation to the size of the nuclear system.Comment: 4 pages, 2 figures, Contributed paper for the 5th Latin American
Symposium on High Energy Physics: V-SILAFAE (2004
Quasinormal modes of D-dimensional de Sitter spacetime
We calculate the exact values of the quasinormal frequencies for an
electromagnetic field and a gravitational perturbation moving in
-dimensional de Sitter spacetime (). We also study the quasinormal
modes of a real massive scalar field and we compare our results with those of
other references.Comment: 26 pages, 1 table. Some changes made according to referee's
suggestions. Matches published version in GR
Electromagnetic quasinormal modes of D-dimensional black holes II
By using the sixth order WKB approximation we calculate for an
electromagnetic field propagating in D-dimensional Schwarzschild and
Schwarzschild de Sitter black holes its quasinormal frequencies for the
fundamental mode and first overtones. We study the dependence of these QN
frequencies on the value of the cosmological constant and the spacetime
dimension. We also compare with the known results for the gravitational
perturbations propagating in the same background. Moreover we exactly compute
the QN frequencies of the electromagnetic field propagating in D-dimensional
massless topological black hole and for charged D-dimensional Nariai spacetime
we exactly calculate the QN frequencies of the coupled electromagnetic and
gravitational perturbations.Comment: 34 pages, 14 figures, 6 table
On algebraic classification of quasi-exactly solvable matrix models
We suggest a generalization of the Lie algebraic approach for constructing
quasi-exactly solvable one-dimensional Schroedinger equations which is due to
Shifman and Turbiner in order to include into consideration matrix models. This
generalization is based on representations of Lie algebras by first-order
matrix differential operators. We have classified inequivalent representations
of the Lie algebras of the dimension up to three by first-order matrix
differential operators in one variable. Next we describe invariant
finite-dimensional subspaces of the representation spaces of the one-,
two-dimensional Lie algebras and of the algebra sl(2,R). These results enable
constructing multi-parameter families of first- and second-order quasi-exactly
solvable models. In particular, we have obtained two classes of quasi-exactly
solvable matrix Schroedinger equations.Comment: LaTeX-file, 16 pages, submitted to J.Phys.A: Math.Ge
Valadier-like formulas for the supremum function II: The compactly indexed case
We generalize and improve the original characterization given by Valadier
[20, Theorem 1] of the subdifferential of the pointwise supremum of convex
functions, involving the subdifferentials of the data functions at nearby
points. We remove the continuity assumption made in that work and obtain a
general formula for such a subdifferential. In particular, when the supremum is
continuous at some point of its domain, but not necessarily at the reference
point, we get a simpler version which gives rise to Valadier formula. Our
starting result is the characterization given in [10, Theorem 4], which uses
the epsilon-subdiferential at the reference point.Comment: 23 page
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