2022 Impact factor 2.8
Special Topics

EPJB Colloquium - Fulfillment of sum-rules and Goldstone modes in many body theories

Schematic representation of the two body mean field

This EPJ B Colloquium article explores applications of the Self-Consistent Random Phase Approximation (SCRPA) approach to Fermi systems with a continuously broken symmetry. Correlations beyond those considered by standard Random Phase Approximation (RPA) are summed up, thereby correcting for the quasi-boson approximation in standard RPA.

Desirable properties of standard RPA, such as fulfilment of the energy-weighted sum rule and the appearance of Goldstone (zero) modes, are preserved. The authors show theoretically as well as numerically, for a model case, that SCRPA maintains all the properties of standard RPA for practically all instances of spontaneously-broken symmetries. A simpler approximate form of SCRPA, the so-called renormalised RPA, also exhibits these properties. The SCRPA equations are first outlined as an eigenvalue problem, and then it is shown how an equivalent many-body Green’s function approach can be formulated.

Managing Editors
Anne Ruimy and Vijala Kiruvanayagam (EDP Sciences) and Sabine Lehr (Springer-Verlag)
Thank you very much, Isabelle! Very timely. And the cover looks fantastic! We are grateful for the great collaboration! Best wishes.

Dirk Helbing, ETH Zurich, Switzerland
Editor EPJ Special Topics 214, 2012

ISSN: 1951-6355 (Print Edition)
ISSN: 1951-6401 (Electronic Edition)

© EDP Sciences and Springer-Verlag