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arXiv · 1402.0283

Multi-Regulator Functional Renormalization Group for Many-Fermion Systems

Yuya Tanizaki·Tetsuo Hatsuda
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Abstract

We propose a method of multi-regulator functional renormalization group (MR-FRG) which is a novel formulation of functional renormalization group with multiple infrared regulators. It is applied to a two-component fermionic system with an attractive contact interaction to study crossover phenomena between the Bardeen-Cooper-Schrieffer (BCS) phase and the Bose-Einstein condensation (BEC) phase. To control both the fermionic one-particle excitations and the bosonic collective excitations,IR regulators are introduced, one for the fermionic two-point function and another for the four-fermion vertex. It is shown that the Nozi\`eres-Schmitt-Rink (NSR) theory, which is successful to capture qualitative features of the BCS-BEC crossover, can be derived from MR-FRG. Some aspects of MR-FRG to go beyond the NSR theory are also discussed.

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Yuya Tanizaki, Tetsuo Hatsuda. 2014-02-03. Multi-Regulator Functional Renormalization Group for Many-Fermion Systems. https://doi.org/10.1142/s0218301317400274

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