Kˉ∗\bar K^* meson in dense matter

We study the properties of $\bar K^*$ mesons in nuclear matter using a unitary approach in coupled channels within the framework of the local hidden gauge formalism and incorporating the $\bar K \pi$ decay channel in matter. The in-medium $\bar K^* N$ interaction accounts for Pauli blocking effects and incorporates the $\bar K^*$ self-energy in a self-consistent manner. We also obtain the $\bar K^*$ (off-shell) spectral function and analyze its behaviour at finite density and momentum. At normal nuclear matter density, the $\bar K^*$ meson feels a moderately attractive potential while the $\bar K^*$ width becomes five times larger than in free space. We estimate the transparency ratio of the $\gamma A \to K^+ K^{* -} A^\prime$ reaction, which we propose as a feasible scenario at present facilities to detect the changes of the properties of the $\bar K^*$ meson in the nuclear medium.Comment: 26 pages, 9 figures, one new section added, version published in Phys. ReV. C, http://link.aps.org/doi/10.1103/PhysRevC.82.04521

Two-particle irreducible effective action approach to nonlinear current conserving approximations in driven systems

Using closed-time path two-particle irreducible coarse-grained effective action (CTP 2PI CGEA) techniques, we study the response of an open interacting electronic system to time-dependent external electromagnetic fields. We show that the CTP 2PI CGEA is invariant under a simultaneous gauge transformation of the external field and the full Schwinger-Keldysh propagator, and that this property holds even when the loop expansion of the CTP 2PI CGEA is truncated at arbitrary order. The effective action approach provides a systematic way of calculating the propagator and response functions of the system, via the Schwinger-Dyson equation and the Bethe-Salpeter equations, respectively. We show that, due to the invariance of the CTP 2PI CGEA under external gauge transformations, the response functions calculated from it satisfy the Ward-Takahashi hierarchy, thus warranting the conservation of the electronic current beyond the expectation value level. We also clarify the connection between nonlinear response theory and the WT hierarchy, and discuss an example of an ad hoc approximation that violate it. These findings may be useful in the study of current fluctuations in correlated electronic pumping devices.Comment: 30 pages. Accepted for publication in JPC

The platinum nuclei: concealed configuration mixing and shape coexistence

The role of configuration mixing in the Pt region is investigated. For this chain of isotopes, the nature of the ground state changes smoothly, being spherical around mass $A\sim 174$ and $A\sim 192$ and deformed around the mid-shell N=104 region. This has a dramatic effect on the systematics of the energy spectra as compared to the systematics in the Pb and Hg nuclei. Interacting Boson Model with configuration mixing calculations are presented for gyromagnetic factors, $\alpha$-decay hindrance factors, and isotope shifts. The necessity of incorporating intruder configurations to obtain an accurate description of the latter properties becomes evident.Comment: Accepted in Physical Review

Latest results for the antikaon-nucleon optical potential

The key question of this letter is whether the K-nucleus optical potential is deep, as it is prefered by the phenomenological fits to kaonic atoms data, or shallow, as it comes out from unitary chiral model calculations. The current experimental situation is reviewed.Comment: 3 pages, 1 figure. Presented at the 21st European Conference on the Few-Body problems in Physics (EFB21), Salamanca, Spain, August 29 - September 3, 201

Strange and charm mesons at FAIR

We study the properties of strange and charm mesons in hot and dense matter within a self-consistent coupled-channel approach for the experimental conditions of density and temperature expected for the CBM experiment at FAIR/GSI. The in-medium solution at finite temperature accounts for Pauli blocking effects, mean-field binding of all the baryons involved, and meson self-energies. We analyze the behaviour in this hot and dense environment of dynamically-generated baryonic resonances together with the evolution with density and temperature of the strange and open-charm meson spectral functions. We test the spectral functions for strange mesons using energy-weighted sum rules and finally discuss the implications of the properties of charm mesons on the D_{s0}(2317) and the predicted X(3700) scalar resonances.Comment: 12 pages, 9 figures, invited talk at XXXI Mazurian Lakes Conference on Physics: Nuclear Physics and the Road to FAIR, August 30-September 6, 2009, Piaski, Polan

Shape evolution and shape coexistence in Pt isotopes: comparing interacting boson model configuration mixing and Gogny mean-field energy surfaces

The evolution of the total energy surface and the nuclear shape in the isotopic chain $^{172-194}$Pt are studied in the framework of the interacting boson model, including configuration mixing. The results are compared with a self-consistent Hartree-Fock-Bogoliubov calculation using the Gogny-D1S interaction and a good agreement between both approaches shows up. The evolution of the deformation parameters points towards the presence of two different coexisting configurations in the region 176 $\leq$ A $\leq$ 186.Comment: Submitted to PR