Application of quantum field theory to condensed systems
Lambert, Colin John
Thesis or dissertation
- © 1979 Colin John Lambert. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
We examine in detail the microscopic theories of Beliaev and Hugenholtz and Pines as applied to an interacting system of bosons in its ground state and demonstrate that these theories are strictly applicable to a zero density gas only. After providing a re-normalization of the time dependent perturbation theory of a many fermion system in its ground state, we reformulate the corresponding boson theory without ab initio approximations concerning the k=0 mode.
The resulting boson perturbation theory has a diagrammatic structure which is topologically identical with the corresponding fermion theory and provided the implicit assumptions concerning convergence are valid, we conclude that a finite fraction of the particles in an arbitrary interacting Bose gas at T=ok will not condense into the k=0 mode.
- Department of Physics, The University of Hull
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- Science Research Council (Great Britain)
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- 39 MB