2014/02/28 by Yuya Tanizaki, Tetsuo Hatsuda
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Condensation #Crossover #Function (biology) #Functional renormalization group #Group (periodic table) #Phase (matter) #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #Renormalization #Renormalization group #cond-mat.quant-gas #cond-mat.supr-con #hep-ph #nucl-th
paper · pdf · doi:10.1142/s0218301317400274
published as International Journal of Modern Physics E Vol. 26 (2017) 1740027 · 18 pages, 5 figures, To be published in Gerry Brown Memorial Book (World Scientific, 2016)
arxiv created 2016/08/13 · openalex created_date 2016/09/16 · openalex publication_date 2017/01/01 · arxiv updated 2017/01/03 · openalex updated_date 2026/08/05
We propose a method of multi-regulator functional renormalization group (MR-FRG) which is a novel formulation of functional renormalization group with multiple infrared (IR) 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 Nozières–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.