Vortex arrays in neutral trapped Fermi gases through the BCS–BEC crossover

Vortex arrays in type-II superconductors reflect the translational symmetry of an infinite system. There are cases, however, such as ultracold trapped Fermi gases and the crust of neutron stars, where finite-size effects make it complex to account for the geometrical arrangement of vortices. Here, we self-consistently generate these arrays of vortices at zero and finite temperature through a microscopic description of the non-homogeneous superfluid based on a differential equation for the local order parameter, obtained by coarse graining the Bogoliubov–de Gennes (BdG) equations. In this way, the strength of the inter-particle interaction is varied along the BCS–BEC crossover, from largely overlapping Cooper pairs in the Bardeen–Cooper–Schrieffer (BCS) limit to dilute composite bosons in the Bose–Einstein condensed (BEC) limit. Detailed comparison with two landmark experiments on ultracold Fermi gases, aimed at revealing the presence of the superfluid phase, brings out several features that make them relevant for other systems in nature as well

Description of Even-Even Xe isotopes in the transitional region of IBM

Properties of Xe isotopes isotopes are studied in the U(5)O(6) transitional region of Interacting Boson Model (IBM-1). The energy levels and B(E2)transition rates are calculated via the affine SU(1,1)Lie Algebra. The agreement with the most recent experimental is acceptable. The evaluated Hamiltonian control parameters suggest a spherical to (/gamma)-soft shape transition and propose the Xe(A=130)nucleus as the best candidate for the E(5)symmetry.Comment: 15 pages,3 figures. I have received an email from the BJPH editor (Prof.Luiz Nunes de Oliveira)which order me to resubmit the final version of paper and note that, paper will appear in Volume 43 of the Brazilian Journal of Physic

Direct empirical correlation between proton-neutron interaction strengths and the growth of collectivity in nuclei

A direct correlation between experimental values of proton-neutron interaction strengths and experimental measures of the growth of collectivity in nuclei is found. In particular, differences in the p-n interaction strengths and differences in growth rates of collectivity in particle-particle (or hole-hole) and particle-hole regions are found to correspond

ANALYTIC FORMULA FOR B(E2) VALUES IN EVEN-EVEN NUCLEI WITH A-GREATER-THAN-60

An approximate analytic formula for calculating B(E2;2(1)+ --> 0(1)+) transition probabilities is proposed. We show that this formula reproduces quite accurately numerical calculations based on the interacting-boson model (IBM), and experimental data for a large number of nuclei from Zn to Pt, and in the actinide region, the largest discrepancies being of the order of 40%. The analytic relation is based on an IBM Hamiltonian, whose four parameters can be estimated using expressions given in the text. Since these expressions are based on a microscopic shell-model description, the formula only requires knowledge of the (N,Z) values of the isotope in question