Biomedical subjects

V Zelevinsky

Publications and source records attributed to V Zelevinsky.

8 recordsLinked to original sources

PubMed2001

Random versus realistic interactions for low-lying nuclear spectra.

We compare the shell-model results for realistic interactions with those obtained for various ensembles of random matrix elements. We show that, although the quantum numbers of the ground states in the even-even nuclei have a high probability ( approximately 60%) to be J(pi)T = 0(+)0, the overlap of those states with the realistic wave functions is very small in average. The transition probabilities B(E2) predicted with random interactions are also too small. The presence of the regular pairing is shown to be a significant element of realistic physics not reproduced by random interactions.

Journal Article↗

PubMed2001

Decoherence and thermalization in a simple bosonic system.

Properties of a parameter-dependent quantum system with the Hamiltonian H(lambda) randomized by fluctuations of the parameter lambda in a narrow range are investigated. The model employed (the interacting boson model-1) exhibits a crossover behavior at a critical parameter value. Due to the fluctuations, individual eigenstates /psi(alpha)(lambda)> of the Hamiltonian become statistical ensembles of states [density matrices rho(alpha)(lambda)], which allows us to study effects related to the decoherence and thermalization. In the decoherence part, we evaluate von Neumann and information entropies of the density matrices rho(alpha)(lambda) and the overlaps of the eigenstates of the density matrix with various physically relevant bases. An increased decoherence at the " phase transitional" point and an exceptional role of the dynamic-symmetry U(5) basis are discovered. In the part devoted to the thermalization, we develop a method of how a given density matrix rho(alpha)(lambda) can be represented by an equivalent canonical (thermal) ensemble. Thermodynamic consequences of the quantum "phase transition" (related, in particular, to the specific heat of the thermal equivalent) are discussed.

Journal Article↗

PubMed2000

Geometric chaoticity leads to ordered spectra for randomly interacting fermions.

A rotationally invariant random interaction ensemble was realized in a single- j fermion model. A statistical approach reveals the random coupling of individual angular momenta as a source for the empirically known dominance of ground states with zero and maximum spin. The interpretation is supported by the structure of the ground state wave functions.

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PubMed1996