BCS-BEC crossover in a relativistic boson-fermion model beyond mean field approximation
BCS-BEC crossover in a relativistic boson-fermion model beyond mean field approximation
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DOI：
10.1103/physrevd.78.034014
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发表时间：
2008-03
影响因子：
5
通讯作者：
Jian Deng;Jin-cheng Wang;Qun Wang
中科院分区：
文献类型：
--
作者：
Jian Deng;Jin-cheng Wang;Qun Wang
研究了相对论超流中Bardeen-Cooper-Schrieffer（BCS）对与玻色-爱因斯坦凝聚（BEC）之间的交叉中的差费米子场的涨落效应。我们在服从整体U（1）对称性的玻色子-费米子模型中工作。为了超越平均场近似，我们使用Cornwall-Jackiw-Tomboulis形式主义来包括高阶贡献。配对凝聚体的量子涨落由非零模式的玻色子提供，玻色子与费米子的相互作用给出了两粒子不可约有效势。它改变了BEC体系中的交叉特性。随着涨落的增加，超流相变成为巨正则系综中的一级相变。我们计算的凝聚，临界温度T{sub c}和粒子丰度作为一个交叉参数的玻色子质量的函数。
We investigate the fluctuation effect of the di-fermion field in the crossover from Bardeen-Cooper-Schrieffer (BCS) pairing to a Bose-Einstein condensate (BEC) in a relativistic superfluid. We work within the boson-fermion model obeying a global U(1) symmetry. To go beyond the mean field approximation we use Cornwall-Jackiw-Tomboulis formalism to include higher-order contributions. The quantum fluctuations of the pairing condensate is provided by bosons in nonzero modes, whose interaction with fermions gives the two-particle-irreducible effective potential. It changes the crossover property in the BEC regime. With the fluctuations the superfluidity phase transition becomes the first order in a grand canonical ensemble. We calculate the condensate, the critical temperature T{sub c} and particle abundances as functions of a crossover parameter of the boson mass.