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Regular version of the site

Article

Functional Integration for Quantum Magnets: New Method and New Results

Annals of Physics. 1990. Vol. 202. No. 1. P. 165-185.

The representation of the generating functional for quantum Heisenberg ferromagnets as an integral over two uncostrained c-number valued fields, charged and neutral, obeying the initial conditions (instead of commonly used periodic boundary conditions) is obtained. With the help of this representation the long-time dynamics of the longitudinal spin component at low temperatures is studied. The infrared-singular part of effective action is calculated for the longitudinal fluctuations in 3D-quantum antiferromagnets as well.