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D. R. Bes

Publications and source records attributed to D. R. Bes.

5 recordsLinked to original sources
arXiv1999

Structure of the vacuum states in the presence of isovector and isoscalar pairing correlations

The long standing problem of proton-neutron pairing and, in particular, the limitations imposed on the solutions by the available symmetries, is revisited. We look for solutions with non-vanishing expectation values of the proton, the neutron and the isoscalar gaps. For an equal number of protons and neutrons we find two solutions where the absolute values of proton and neutrons gaps are equal but have the same or opposite sign. The behavior and structure of these solutions differ for spin saturated (single l-shell) and spin unsaturared systems (single j-shell). In the former case the BCS results are checked against an exact calculation.

nucl-th↗
arXiv1997

Baby skyrmions on the sphere

We study a model for two-dimensional skyrmions on a sphere of radius L. Such model simulates a skyrmion lattice of density W/(2 πL^2), where W is the skyrmion winding number. We show that, to a very good approximation, physical results depend only on the product αL^4, where αis the strength of potential term. In the range αL^4 approx. or less than 3 the order parameter vanishes, there is a uniform distribution of the density over the whole surface and the energy of the W=2 sector lies above twice the energy of the W=1 sector. If αL^4 approx. or greater than 6 the order parameter approaches unity and the density concentrates near one of the poles. Moreover the disoliton is always bound. We also present a variational solution to the field equations for which the pure αL^4-dependence is exact. Finally, some consequences of our results for the Quantum Hall Effect are discussed.

hep-th↗
arXiv1994

Becchi-Rouet-Stora-Tyutin quantization of a soliton model in 2+1 dimensions

The Becchi-Rouet-Stora-Tyutin (BRST) method is applied to the quantization of the solitons of the non-linear $O(3)$ model in $2+1$ dimensions. We show that this method allows for a simple and systematic treatment of zero-modes with a non-commuting algebra. We obtain the expression of the BRST hamiltonian and show that the residual interaction can be perturbatively treated in an IR-divergence-free way. As an application of the formalism we explicitly evaluate the two-loop correction to the soliton mass.

hep-th↗
arXiv1993

A Systematic Treatment of Triaxial Systems at High Spins. II

The BRST treatment of triaxial nuclei rotating at high spins, which had been previously developed, is extended to relate states with neighboring values of the angular momentum $I$. As a consequence, the irreducible multipole transition operators can be unambiguously separated into their physical and spurious components. As a by product, we give explicit expressions for the operators associated with the Goldstone-Nambu modes in terms of the final orthonormal set of physical and spurious modes.

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