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Fermionic functional renormalization group for first-order phase transitions: a mean-field model

R. Gersch·J. Reiss·C. Honerkamp
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Abstract

First-order phase transitions in many-fermion systems are not detected in the susceptibility analysis of common renormalization-group (RG) approaches. Here we introduce a counterterm technique within the functional renormalization-group (fRG) formalism which allows access to all stable and metastable configurations. It becomes possible to study symmetry-broken states which occur through first-order transitions as well as hysteresis phenomena. For continuous transitions, the standard results are reproduced. As an example, we study discrete-symmetry breaking in a mean-field model for a commensurate charge-density wave. An additional benefit of the approach is that away from the critical temperature for the breaking of discrete symmetries large interactions can be avoided at all RG scales.

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R. Gersch, J. Reiss, C. Honerkamp. 2007-02-08. Fermionic functional renormalization group for first-order phase transitions: a mean-field model. https://doi.org/10.1088/1367-2630%2F8%2F12%2F320

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