Naslov
Collective excitations in the Unitary Correlation Operator Method and relativistic QRPA studies of exotic nuclei

Autori
Paar, Nils ; Papakonstantinou, Panagiota ; Hergert, Heiko ; Roth, Robert

Izvornik
Physics of Atomic Nuclei (1063-7788) 69 (2006), 8; 1345-1352

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
collective excitations; exotic nuclei; nucleon-nucleon interaction; RPA; QRPA; correlation energies; pygmy resonances; giant resonances

Sažetak
The collective excitation phenomena in atomic nuclei are studied in two different formulations of the Random Phase Approximation (RPA): (i) RPA based on correlated realistic nucleon-nucleon interactions constructed within the Unitary Correlation Operator Method (UCOM), and (ii) relativistic RPA (RRPA) derived from effective Lagrangians with density-dependent meson-exchange interactions. The former includes the dominant interaction-induced short-range central and tensor correlations by means of an unitary transformation. It is shown that UCOM-RPA correlations induced by collective nuclear vibrations recover a part of the residual long-range correlations that are not explicitly included in the UCOM Hartree-Fock ground state. Both RPA models are employed in studies of the isoscalar monopole resonance (ISGMR) in closed-shell nuclei across the nuclide chart, with an emphasis on the sensitivity of its properties on the constraints for the range of the UCOM correlation functions. Within the Relativistic Quasiparticle RPA (RQRPA) based on Relativistic Hartree-Bogoliubov model, the occurrence of pronounced low-lying dipole excitations is predicted in nuclei towards the proton drip-line. From the analysis of the transition densities and the structure of the RQRPA amplitudes, it is shown that these states correspond to the proton pygmy dipole resonance.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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