# Extended theory of finite Fermi systems: Application to the collective and noncollective E1 strength in {sup 208}Pb

## Abstract

The Extended Theory of Finite Fermi Systems is based on the conventional Landau-Migdal theory and includes the coupling to the low-lying phonons in a consistent way. The phonons give rise to a fragmentation of the single-particle strength and to a compression of the single-particle spectrum. Both effects are crucial for a quantitative understanding of nuclear structure properties. We demonstrate the effects on the electric dipole states in {sup 208}Pb (which possesses 50% more neutrons then protons) where we calculated the low-lying noncollective spectrum as well as the high-lying collective resonances. Below 8 MeV, where one expects the so-called isovector pygmy resonances, we also find a strong admixture of isoscalar strength that comes from the coupling to the high-lying isoscalar electric dipole resonance, which we obtain at about 22 MeV. The transition density of this resonance is very similar to the breathing mode, which we also calculated. We shall show that the extended theory is the correct approach for self-consistent calculations, where one starts with effective Lagrangians and effective Hamiltonians, respectively, if one wishes to describe simultaneously collective and noncollective properties of the nuclear spectrum. In all cases for which experimental data exist the agreement with the present theory results ismore »

- Authors:

- Institut fuer Kernphysik, Forschungszentrum Juelich, D-52425 Juelich (Germany)
- (Russian Federation)
- (Poland)
- Institute of Physics and Power Engineering, RU-249020 Obninsk (Russian Federation)

- Publication Date:

- OSTI Identifier:
- 20990954

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevC.75.014315; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; COUPLING; DENSITY; ELECTRIC DIPOLES; HAMILTONIANS; ISOVECTORS; LAGRANGIAN FUNCTION; LEAD 208; MEV RANGE; MIGDAL THEORY; NEUTRONS; NUCLEAR STRUCTURE; PARTICLES; PHONONS; PROTONS; RESONANCE; SPECTRA

### Citation Formats

```
Tselyaev, V., Institute of Physics, St. Petersburg University, St. Petersburg, Speth, J., Institute of Nuclear Physics, PAN, PL-31-342 Cracow, Gruemmer, F., Krewald, S., Avdeenkov, A., Tertychny, G., Institute of Physics and Power Engineering, RU-249020 Obninsk, and Litvinova, E.
```*Extended theory of finite Fermi systems: Application to the collective and noncollective E1 strength in {sup 208}Pb*. United States: N. p., 2007.
Web. doi:10.1103/PHYSREVC.75.014315.

```
Tselyaev, V., Institute of Physics, St. Petersburg University, St. Petersburg, Speth, J., Institute of Nuclear Physics, PAN, PL-31-342 Cracow, Gruemmer, F., Krewald, S., Avdeenkov, A., Tertychny, G., Institute of Physics and Power Engineering, RU-249020 Obninsk, & Litvinova, E.
```*Extended theory of finite Fermi systems: Application to the collective and noncollective E1 strength in {sup 208}Pb*. United States. doi:10.1103/PHYSREVC.75.014315.

```
Tselyaev, V., Institute of Physics, St. Petersburg University, St. Petersburg, Speth, J., Institute of Nuclear Physics, PAN, PL-31-342 Cracow, Gruemmer, F., Krewald, S., Avdeenkov, A., Tertychny, G., Institute of Physics and Power Engineering, RU-249020 Obninsk, and Litvinova, E. Mon .
"Extended theory of finite Fermi systems: Application to the collective and noncollective E1 strength in {sup 208}Pb". United States.
doi:10.1103/PHYSREVC.75.014315.
```

```
@article{osti_20990954,
```

title = {Extended theory of finite Fermi systems: Application to the collective and noncollective E1 strength in {sup 208}Pb},

author = {Tselyaev, V. and Institute of Physics, St. Petersburg University, St. Petersburg and Speth, J. and Institute of Nuclear Physics, PAN, PL-31-342 Cracow and Gruemmer, F. and Krewald, S. and Avdeenkov, A. and Tertychny, G. and Institute of Physics and Power Engineering, RU-249020 Obninsk and Litvinova, E.},

abstractNote = {The Extended Theory of Finite Fermi Systems is based on the conventional Landau-Migdal theory and includes the coupling to the low-lying phonons in a consistent way. The phonons give rise to a fragmentation of the single-particle strength and to a compression of the single-particle spectrum. Both effects are crucial for a quantitative understanding of nuclear structure properties. We demonstrate the effects on the electric dipole states in {sup 208}Pb (which possesses 50% more neutrons then protons) where we calculated the low-lying noncollective spectrum as well as the high-lying collective resonances. Below 8 MeV, where one expects the so-called isovector pygmy resonances, we also find a strong admixture of isoscalar strength that comes from the coupling to the high-lying isoscalar electric dipole resonance, which we obtain at about 22 MeV. The transition density of this resonance is very similar to the breathing mode, which we also calculated. We shall show that the extended theory is the correct approach for self-consistent calculations, where one starts with effective Lagrangians and effective Hamiltonians, respectively, if one wishes to describe simultaneously collective and noncollective properties of the nuclear spectrum. In all cases for which experimental data exist the agreement with the present theory results is good.},

doi = {10.1103/PHYSREVC.75.014315},

journal = {Physical Review. C, Nuclear Physics},

number = 1,

volume = 75,

place = {United States},

year = {Mon Jan 15 00:00:00 EST 2007},

month = {Mon Jan 15 00:00:00 EST 2007}

}