论文标题
单一费米气体的第四个集群和病毒系数，以任意质量比
Fourth cluster and virial coefficients of a unitary Fermi gas for an arbitrary mass ratio
论文作者
论文摘要
我们将均匀统一自旋1/2费米气体的第四个集群系数作为内态质量比的函数，而不是受到3型或4体efimov效应的限制的间隔。为此，我们使用2016年的猜想（在2020年通过HOU和DRUT验证了相等的质量），以数值效率的公式，使得超过角动量收敛的总和更快，这在较大的质量比至关重要。平均簇系数与相等的化学电位相关，并不具有恒定的符号，并且迅速增加接近Efimovian阈值。我们还获得了第四个病毒系数，我们认为这是相互作用引起的4体相关性的非常差的指标。我们分析所有$ n $的无限质量杂质费米恩订单$ n $ + 1的集群系数，以$ n = 3 $匹配猜想。最后，在谐波电位上，我们预测3 + 1群集系数的非单调行为具有捕获频率，接近质量比，该系数在均匀情况下消失了。
We calculate the fourth cluster coefficients of the homogeneous unitary spin 1/2 Fermi gas as functions of the internal-state mass ratio, over intervals constrained by the 3- or 4-body Efimov effect. For this we use our 2016 conjecture (validated for equal masses by Hou and Drut in 2020) in a numerically efficient formulation making the sum over angular momentum converge faster, which is crucial at large mass ratio. The mean cluster coefficient, relevant for equal chemical potentials, is not of constant sign and increases rapidly close to the Efimovian thresholds. We also get the fourth virial coefficients, which we find to be very poor indicators of interaction-induced 4-body correlations. We obtain analytically for all $n$ the cluster coefficients of order $n$ + 1 for an infinity-mass impurity fermion, matching the conjecture for $n=3$. Finally, in a harmonic potential, we predict a non-monotonic behavior of the 3 + 1 cluster coefficient with trapping frequency, near mass ratios where this coefficient vanishes in the homogeneous case.
