Nuclear response theory with multiphonon coupling in a covariant framework

Abstract

Background: Nuclear excited states within a wide range of excitation energies are formally described by the linear response theory. Besides its conventional formulation within the quasiparticle random phase approximation (QRPA) representing excited states as two correlated quasiparticles (2q), there exist extensions for 4q configurations. Such extended approaches are quite successful in the description of gross properties of nuclear spectra, however, accounting for many of their fine features requires further extension of the configuration space. Purpose: This work aims at the development of an approach which is capable of such an extension as well as of reproducing and predicting fine spectral properties, which are of special interest at low energies. Method: The method is based on the covariant density functional theory and time blocking approximation, which is extended for couplings between quasiparticles and multiphonon excitations. Results: The covariant multiphonon response theory is developed and adopted for nuclear structure calculations in medium-mass and heavy nuclei. The equations are formulated in both general and coupled forms in the spherical basis. Conclusions: The developed covariant multiphonon response theory represents a new generation of the approaches to nuclear response, which aims at a unified description of both high-frequency collective states and low-energy spectroscopy in medium-mass and heavy nuclei.

version 3; 11 pages, 7 figures. arXiv admin note: text overlap with arXiv:1308.3184 on basic notions

References in corpus (11)

• Isospin Character of the Pygmy Dipole Resonance in 124Sn
• Relativistic quasiparticle time blocking approximation. Dipole response of open-shell nuclei
• Covariant theory of particle-vibrational coupling and its effect on the single-particle spectrum
• Particle-vibration coupling within covariant density functional theory
• Relativistic quasiparticle time blocking approximation. II. Pygmy dipole resonance in neutron-rich nuclei
• The Gamow-Teller response within Skyrme random-phase approximation plus particle-vibration coupling
• Population of dipole states via isoscalar probes: the splitting of pygmy dipole resonance in ${}^{124}$Sn}
• Gamow-Teller response and its spreading mechanism in doubly magic nuclei
• Fragmentation of spin-dipole strength in ${}^{90}$Zr and ${}^{208}$Pb
• Microscopic description of the pygmy and giant electric dipole resonances in stable Ca isotopes
• Extended Theory of Finite Fermi Systems: Application to the collective and non-collective E1 strength in ${}^{208}$Pb