G. Garbarino

Weak decays of medium and heavy Lambda hypernuclei

We have made a new evaluation of the L decay width in nuclear matter within the propagator method. Through the local density approximation it is possible to obtain results in finite nuclei. We have also studied the dependence of the widths on the NN and LN strong short-range correlations. Using reasonable values for the parameters that control these correlations, as well as realistic nuclear densities and L wave functions, we show that it is possible to reproduce the experimental decay rates in a wide range of mass numbers ~from medium to heavy hypernuclei!; however, the question related to the G n /G p ratio remains open.

Bell's inequality tests: from photons to B-mesons

We analyse the recent claim that a violation of a Bells inequality has been observed in the B-meson system [A. Go, J. Mod. Opt. 51 991 (2004)]. The results of this experiment are a convincing proof of quantum entanglement in B-meson pairs similar to that shown by polarization entangled photon pairs. However, we conclude that the tested inequality is not a genuine Bells inequality and thus cannot discriminate between quantum mechanics and local realistic approaches.

Bell's Inequality Tests with Meson-Antimeson Pairs

Recent proposals to test Bell’s inequalities with entangled pairs of pseudoscalar mesons are reviewed. This includes pairs of neutral kaons or B-mesons and offers some hope to close both the locality and the detection loopholes. Specific difficulties, however, appear thus invalidating most of those proposals. The best option requires the use of kaon regeneration effects and could lead to a successful test if moderate K0 and k̄0 detection efficiencies are achieved.

Functional approach to the non-mesonic decay of Λ-hypernuclei

Abstract We present an evaluation of the non-mesonic decay widths for Λ -hypernuclei ( ΛN → NN , ΛNN → NNN ) within the framework of the polarization propagator method. The full Λ self-energy is evaluated microscopically in nuclear matter by using the functional approach, which supplies a theoretically well grounded approximation scheme for the classification of the relevant diagrams, according to the prescriptions of the bosonic loop expansion. We employ average Fermi momenta, suitably adapted to different mass number regions (medium-light, medium and heavy hypernuclei). Moreover, we study the dependence of the decay rates on the NN and ΛN short range correlations. With a proper choice of the parameters which control these correlations in the new approximation scheme, it is possible to reproduce the experimental decay widths for A ≳10 hypernuclei.

Static properties of nuclear matter within the Boson Loop Expansion

Abstract The use of the Boson Loop Expansion is proposed for investigating the static properties of nuclear matter. We explicitly consider a schematic dynamical model in which nucleons interact with the scalar–isoscalar σ meson. The suggested approximation scheme is examined in detail at the mean field level and at the one- and two-loop orders. The relevant formulas are provided to derive the binding energy per nucleon, the pressure and the compressibility of nuclear matter. Numerical results of the binding energy at the one-loop order are presented for Walecka’s σ - ω model in order to discuss the degree of convergence of the Boson Loop Expansion.

DECAY RATES OF MEDIUM-HEAVY Λ-HYPERNUCLEI WITHIN THE PROPAGATOR METHOD

The Lambda decay rates in nuclei has been calculated in ref. 1 using the Propagator Method in Local Density Approximation. We have studied the dependence of the widths (including the one for the two-body induced process Lambda NN -> NNN) on the N-N and Lambda-N short range correlations. Using a reasonable parametrization of these correlations, as well as realistic nuclear densities and Lambda wave functions, we reproduce, for the first time, the experimental non-mesonic widths from medium to heavy hypernuclei.