Jörg Jäckel

University of Heidelberg, Germany

Spontaneous Symmetry Breaking by the Condensation of Composites of Fermions

In this seminar I want to address some problems of partial bosonization in systems with strongly interacting fermions. Why is Mean Field Theory very deeply affected by ambiguities in the choice of the mean fields? After finding that these ambiguities are due to an insufficient approximation I will show how they can be removed in the context of the renormalization group. This leads to the concept of scale dependent degrees of freedom. Moreover, I would like to briefly discuss the 2PI bosonic effective action as an alternative method. As an application of this I investigate if a six fermion instanton interaction can generate color octet condensates in the vacuum.

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