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- Joel Feldman, Detlef Lehmann, Horst Knn, Eugene Trubowitz, Mathematik Eth-Zentrum
- 1994

- Detlef Lehmann
- 2002

The nonrelativistic many-electron system in the forward, exchange and BCS approximation is considered. In this approximation, the model is explicitly solvable for arbitrary space dimension d. The partition function and the correlation functions are given by finite-dimensional integral representations. Renormalization effects as well as symmetry breaking can… (More)

- Detlef Lehmann
- 2000

We prove that the global minimum of the real part of the full effective potential of the many electron system with attractive delta interaction is in fact given by the BCS mean field configuration. This is a consequence of a simple bound which is obtained by applying Hadamard's inequality to the functional determinant. The second order Taylor expansion… (More)

- Detlef Lehmann
- 2001

For a gaussian interaction V (x, y) = λ e − x 2 +y 2 2r 2 with long range r >> ℓ B , ℓ B the magnetic length, we rigorously prove that the eigenvalues of the finite volume

In these lectures, we consider a many-body system that is somewhat unusual in that the Fermi surface survives the turning on of all suuciently weak short range interactions. The system consists of a gas of fermions with prescribed, strictly positive, density, together with a crystal lattice of magnetic ions. The fermions interact with each other through a… (More)

- D Lehmann
- 1998

In an effective theory containing only quark degrees of freedom, such as the extended Nambu–Jona–Lasinio model, the influence of the axial anomaly can be incorporated by a self-interaction of the 't Hooft determinant type. I will show that this leads to a significant suppression of the η ′ coupling g η ′ qq to dynamical quarks which suggests a suppression… (More)

- Detlef Lehmann
- 2000

In many field theoretical models one has to resum two-and four-legged subdia-grams in order to determine their behaviour. In this article we present a novel formalism which does this in a nice way. It is based on the central limit theorem of probability and an inversion formula for matrices which is obtained by repeated application of the Feshbach… (More)

- Detlef Lehmann
- 1983

- D Lehmann
- 2007

In an eeective theory containing only quark degrees of freedom, such as the extended Nambu{Jona{Lasinio model, the innuence of the axial anomaly can be incorporated by a self-interaction of the 't Hooft determinant type. I will show that this leads to a signiicant suppression of the 0 coupling g 0 qq to dynamical quarks which suggests a suppression of the 0… (More)

- Gerhard Bergholz, Detlef Lehmann
- Elektronische Informationsverarbeitung und…
- 1984