Uncertainty relations for a q-deformed coherent spin state

A Coherent Spin State (CSS) is defined as an eigenstate of the spin component in the direction specified by angles (θ₀,?₀). This state satisfies minimum uncertainty relation, with uncertainties equally distributed on any two orthogonal components normal to the direction of the total spin vector 〈S〉. Starting from this concept, we apply the notion of CSS to quantum groups and discuss the properties of q-deformed CSS and the associated uncertainty relations. We show that these states behave as Intelligent Spin States (ISS) on two orthogonal components normal to the direction of the mean value of the spin operator.     

Calculation of the beta decay of Pd. Quasiparticle random phase approximation results

Single beta decay transitions in ^114–120Pd are calculated. Theoreticalβ⁺ and β⁻ strength distributions, for transitions to 1⁺ states in the nuclei ^114–120Ag and ^114–120Rh, are obtained in the framework of the quasiparticle random phase approximation (QRPA). The effective two-body interaction which is used in the calculations is constructed from the Bonn one-boson-exchange potential (OBEP). Particle-hole and particle-particle like channels of the two-body force are included in the definition of the QRPA matrix equations. Effects associated with the particle number violation of the quasiparticle mean field are accounted for by using a particle-number-projected version of the QRPA formalism. Theoretical strength distributions for the β⁻ and β⁺ braches are shown and compared with data.     

Structure of symmetry restoring interactions: A modified BCS plus rotational approach for a schematic model space

Symmetry restoring interactions are constructed for pairing and cranking Hamiltonians in a deformed single particle basis. The structure of the interactions is explicitly shown and the effective Hamiltonian is treated in the framework of a modified BCS + RPA approach. Numerical results for a schematic single particle basis, which consists of a splitj=3/2 multiplet, are discussed.     

On the temperature dependence of the level density parameter and its effect upon neutron evaporation spectra

Effects associated with the temperature dependence of the level density parameter,a(T), are investigated in connection with neutron evaporation processes. Different approximations, for this temperature dependence, are compared for the case of neutron emission from the compound nucleus²⁰⁹Pb.     

The role of the continuum and the spurious 1− transitions in incoherent μ −−e− conversion rate calculations

By using the Continuum RPA (CRPA) method, the incoherent transition strength of the exotic μ ⁻−e⁻ conversion in nuclei is investigated. The question whether excited nuclear states lying high in the continuum give an important contribution to the incoherent rate is addressed. Results for ⁴⁰Ca are compared with those obtained previously for ²⁰⁸Pb. For both nuclei we then investigate in detail the admixture of spurious components in the rate coming from 1⁻ excitations, within the self-consistent CRPA with Skyrme interactions as well as within a less consistent version. We employ and compare two methods for removing the spurious strength: the use of effective operators, as done in a previous work for ²⁰⁸Pb, or simply the exclusion of the spurious state appearing close to zero energy. In all cases, the correction achieved is quite large. Presented by P. Papakonstantinou at the Workshop on calculation of double-beta-decay matrix elements (MEDEX’05), Corfu, Greece, September 26–29, 2005.     

Theoretical estimates of the 1/2− (693 keV) 3/2x002B;x002B;x002B;first-forbidden beta decay transition in111Ag

The matrix elements governing the 693 keV first-forbidden beta decay transition in¹¹¹Ag are calculated in terms of the quasiparticle-phonon coupling model. Electromagnetic properties are evaluated, in addition, for various transitions in¹¹¹Ag and¹¹¹Cd. The theoretical results show a reasonable agreement with respect to recently reported experimental values.     

Lattice density waves in nuclear matter at finite temperature

Symmetric nuclear matter at finite temperature is studied, within the Thermal Hartree Fock framework, employing lattice density waves and density dependent forces of the Skyrme type. The disappearance of clusters at finite temperature is described and its characteristics are quantiatively determined.     

The nuclear level-density parameter and temperature-dependent effects in finite nuclei

The influence of temperature-dependent effects on nuclear level densities is investigated. The explicit treatment of thermal degrees of freedom, within the Darwin-Fowler method, shows that the level-density parameter strongly differs from a constant value at low temperatures. The formalism is presented both for normal and superfluid systems.     

On the Concept of Entropy for Quantum Decaying Systems

The classical concept of entropy was successfully extended to quantum mechanics by the introduction of the density operator formalism. However, further extensions to quantum decaying states have been hampered by conceptual difficulties associated to the particular nature of these states. In this work we address this problem, by (i) pointing out the difficulties that appear when one tries a consistent definition for this entropy, and (ii) building up a plausible formalism for it, which is based on the use of coherent complex states in the context of a path integration.