NOVEL TOPOLOGICAL FEATURES OF THE O(3) NONLINEAR SIGMA MODEL IN 2+1 DIMENSIONS
- 10 August 1989
- journal article
- Published by World Scientific Pub Co Pte Ltd in Modern Physics Letters A
- Vol. 4 (15) , 1457-1462
- https://doi.org/10.1142/s0217732389001660
Abstract
We investigate the configuration space topology of the O(3) nonlinear sigma model in 2+1 dimensions, when the fields satisfy periodic boundary conditions. We show the fundamental group of the configuration space to be nonabelian. We associate three integer invariants to each homotopic class of paths, one of which is related to the Hopf invariant. We find that consistent quantization requires the coefficient of the Hopf term in the action to be 0 to π.Keywords
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