The Gamow-Teller resonance in finite nuclei in the relativistic random phase approximation

Gamow-Teller (GT) resonances in finite nuclei are studied in a fully consistent relativistic random phase approximation (RPA) framework. A relativistic form of the Landau-Migdal contact interaction in the spin-isospin channel is adopted, which has a vector part as well as a time-like component. This choice ensures that the GT excitation energy in nuclear matter is correctly reproduced in the non-relativistic limit. The GT response functions of doubly magic nuclei ⁴⁸Ca, ⁹⁰Zr and ²⁰⁸Pb are calculated using the parameter set NL3 and g = 0.6. It is found that the effects related to Dirac sea states account for a reduction of 6-7% in the GT sum rule. The quenching of the GT strength in finite nuclei implies that the value of g in the relativistic model might be enlarged about 7%. The time component in the relativistic form of the Landau-Migdal force plays a little role in GT resonance energies.Received: 20 November 2003, Published online: 26 May 2004PACS: 21.60.-n Nuclear structure models and methods - 21.60.Jz Hartree-Fock and random-phase approximations - 24.10.Jv Relativistic models - 24.30.Cz Giant resonances