Instantons in field strength

It is shown that the field strength formulated Yang-Mills theory yields the same semiclassics as the standard formulation in terms of the gauge potential. This concerns the classical instanton solutions as well as the quantum fluctuations around the instanton. 1 Supported by DFG under contract Re 856/1 − 1 1 1. Introduction Yang-Mills (YM) theories can be reformulated entirely in terms of field strength thereby eliminating the gauge potential [1, 2, 3]. The field strength formulation allows for a non-perturbative treatment of the gluon self-interaction and offers a simple description of the non-perturbative vacuum where the gauge bosons are pre-sumable condensed. In the so called FSA an effective action for the field strength is obtained which contains a term of order ¯ h with an explicit energy scale. Hence in the FSA the anomalous breaking of scale invariance is described already at tree level [2]. At this level the YM vacuum is determined by homogeneous field configurations with constant F