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arXiv · hep-th/9605037

Exact Flow Equations and the U(1)-Problem

J. M. Pawlowski
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Abstract

The effective action of a SU(N)-gauge theory coupled to fermions is evaluated at a large infrared cut-off scale k within the path integral approach. The gauge field measure includes topologically non-trivial configurations (instantons). Due to the explicit infrared regularisation there are no gauge field zero modes. The Dirac operator of instanton configurations shows a zero mode even after the infrared regularisation, which leads to U_A(1)-violating terms in the effective action. These terms are calculated in the limit of large scales k.

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J. M. Pawlowski. 1998-05-18. Exact Flow Equations and the U(1)-Problem. https://doi.org/10.1103/physrevd.58.045011

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