Studies on quantum field theory and statistical mechanics

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6897243

Zhang, S

This dissertation is a summary of research in various areas of theoretical physics and is divided into three parts. In the first part, quantum fluctuations of the recently proposed superconducting cosmic strings are studied. It is found that vortices on the string world sheet represent an important class of fluctuation modes which tend to disorder the system. Both heuristic arguments and detailed renormalization group analysis reveal that these vortices do not appear in bound pairs but rather from a gas of free vortices. Based on this observation we argue that this fluctuation mode violates the topological conservation law on which superconductivity is based. Anomalies and topological aspects of supersymmetric quantum field theories are studied in the second part of this dissertation. Using the superspace formulation of the N = 1 spinning string, we obtain a path integral measure which is free from the world-sheet general coordinate as well as the supersymmetry anomalies and therefore determine the conformal anomaly and critical dimension of the spinning string. We also apply Fujikawa's formalism to computer the chiral anomaly in conformal as well as ordinary supergravity. Finally, we given a Noether-method construction of the supersymmetrized Chern-Simons term in five dimensional supergravity. In the last part of this dissertation, the soliton excitations in the quarter-filled Peierls-Hubbard model are investigated in both the large and the small U limit. For a strictly one dimensional system at zero temperature, we find that solitons in both limits are in one-to-one correspondence, while in the presence of weak three dimensional couplings or at finite temperature, the large U systems differ qualitatively from the small U systems in that the spin associated with the solitons ceases to be a sharp quantum observable.

• Research Organization: State Univ. of New York, Stony Brook, NY (USA)
• OSTI ID: 6897243
• Country of Publication: United States
• Language: English

Related Subjects

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656100 -- Condensed Matter Physics-- Superconductivity
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71 CLASSICAL AND QUANTUM MECHANICS
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
75 CONDENSED MATTER PHYSICS
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99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
CALCULATION METHODS
COMPOSITE MODELS
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EXTENDED PARTICLE MODEL
FIELD THEORIES
INFORMATION
MATHEMATICAL MODELS
MECHANICS
NUMERICAL DATA
PARTICLE MODELS
PHYSICAL PROPERTIES
QUANTUM FIELD THEORY
QUARK MODEL
QUASI PARTICLES
SOLITONS
STATISTICAL MECHANICS
STRING MODELS
SUPERCONDUCTIVITY
THEORETICAL DATA