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HK: Hadronen und Kerne

HK 68: Fundamentale theoretische Arbeiten

HK 68.5: Gruppenbericht

Donnerstag, 27. März 1997, 18:30–19:00, HS L

Symmetry Conserving Dynamical Mappings — •Z. Aouissat and J. Wambach — Institut f"ur KernPhysik - Theorie, Thechnische Hochschule Darmstadt, Schlossgartenstr. 9, D-64289 Darmstadt

It is well known that perturbative methods are trivially symmetry conserving. They are however of no use for studying collective phenomena such as bound states or resonances. They are also inadequate for studying phase transitions. When dealing with such problems it is crucial to develop nonperturbative methods which are, at the same time, capable of properly handeling the symmetries. In this respect, two symmetry-conserving approximation schemes will be presented and compared to each other. The first is derived from the quasiparticle RPA [1] with a variational ground state similar to the one of the Gaussian Effective Potential. The second, more systematic, is based on the Holstein-Primakoff mapping and corresponds to the well known 1/N expansion [2]. Applications in the linear sigma-model will be discussed.

[1] Z. Aouissat, G. Chanfray, P. Schuck, J. Wambach, Nucl. Phys. A 603 (1996) 458.

[2] Z. Aouissat, P. Schuck, J. Wambach, To be submitted for publication