Tan contact and universal high momentum behavior of the fermion propagator in the BCS-BEC crossover

被引：17
作者：
Boettcher, Igor [1 ]
Diehl, Sebastian [2 ,3 ]
Pawlowski, Jan M. [1 ,4 ]
Wetterich, Christof [1 ]
机构：
[1] Heidelberg Univ, Inst Theoret Phys, D-69120 Heidelberg, Germany
[2] Univ Innsbruck, Inst Theoret Phys, A-6020 Innsbruck, Austria
[3] Austrian Acad Sci, Inst Quantum Opt & Quantum Informat, A-6020 Innsbruck, Austria
[4] GSI Helmholtzzentrum Schwerionenforsch mbH, ExtreMe Matter Inst EMMI, D-64291 Darmstadt, Germany
来源：
PHYSICAL REVIEW A | 2013年 / 87卷 / 02期
基金：
奥地利科学基金会;
关键词：
RENORMALIZATION-GROUP APPROACH; BOSE-EINSTEIN CONDENSATION; FUNCTIONAL RENORMALIZATION; SUPERCONDUCTIVITY; THERMODYNAMICS; TRANSITION; EQUATION; GAS;
D O I：
10.1103/PhysRevA.87.023606
中图分类号：
O43 [光学];
学科分类号：
070207 ; 0803 ;
摘要：
We derive the universal high momentum factorization of the fermion self-energy in the BCS-BEC crossover of ultracold atoms using nonperturbative quantum field theoretical methods. This property is then employed to compute the Tan contact as a function of interaction strength, temperature, and chemical potential or density. We clarify the mechanism of the factorization from an analysis of the self-consistent Schwinger-Dyson equation for the fermion propagator and compute the perturbative contact on the BCS and Bose-Einstein condensate (BEC) sides within this framework. A functional renormalization group approach is then put forward, which makes it possible to determine the contact over the whole crossover and, in particular, for the unitary Fermi gas. We present numerical results from an implementation of the renormalization group equations within a basic truncation scheme. DOI: 10.1103/PhysRevA.87.023606
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页数：17
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