A Note on Wess-Zumino Terms and Discrete Symmetries
نویسنده
چکیده
Sigma models in which the integer coefficient of the Wess-Zumino term vanishes are easy to construct. This is the case if all flavor symmetries are vectorlike. We show that there is a subset of SU(N)× SU(N) vectorlike sigma models in which the Wess-Zumino term vanishes for reasons of symmetry as well. However, there is no chiral sigma model in which the Wess-Zumino term vanishes for reasons of symmetry. This can be understood in the sigma model basis as a consequence of an index theorem for the axialvector coupling matrix. We prove this index theorem directly from the SU(N)× SU(N) algebra. PACS: 11.30.Rd; 12.38.Aw; 12.90.+b; 11.30.Er
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