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Physics Faculty Research & Creative Works

Quantum theory

2002

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Full-Text Articles in Physical Sciences and Mathematics

Local Versus Nonlocal Order-Parameter Field Theories For Quantum Phase Transitions, Dietrich Belitz, Theodore R. Kirkpatrick, Thomas Vojta Apr 2002

Local Versus Nonlocal Order-Parameter Field Theories For Quantum Phase Transitions, Dietrich Belitz, Theodore R. Kirkpatrick, Thomas Vojta

Physics Faculty Research & Creative Works

General conditions are formulated that allow us to determine which quantum phase transitions in itinerant electron systems can be described by a local Landau-Ginzburg-Wilson (LGW) theory solely in terms of the order parameter. A crucial question is the degree to which the order parameter fluctuations couple to other soft modes. Three general classes of zero-wave-number order parameters, in the particle-hole spin-singlet and spin-triplet channels and in the particle-particle channel, respectively, are considered. It is shown that the particle-hole spin-singlet class does allow for a local LGW theory, while the other two classes do not. The implications of this result for ...