论文标题
超越排斥性SU（N）费米气体的普遍性
Beyond universality in repulsive SU(N) Fermi gases
论文作者
论文摘要
稀释的费米气体中的流动铁磁学预计会在气体参数的值下出现，其中二阶扰动理论不够准确，无法正确描述系统。我们已经重新审视了SU（N）费米子的扰动理论，并将其泛化得出至三阶，从气体参数和极化方面。我们的结果与$ s = 1/2 $的硬球和软球电位的量子蒙特卡洛结果令人满意地一致。尽管相变的性质取决于相互作用的潜力，但我们发现，对于硬球电位，保证了相变。虽然对于$ s = 1/2 $，我们观察到准连续的过渡，对于旋转$ 3/2 $和$ 5/2 $，可以找到一阶相变。对于较大的自旋，发生双重转变（连续和不连续的）。当自旋增加时，临界密度会大大降低，从而使相变的超速稀释费米斯气体更容易访问。据报道，据报道，据报道，据报道，据报道，据报道，据报道，据报道，YB和SR的费米气体（分别为$ 5/2 $和$ 9/2 $）的YB和SR估计。
Itinerant ferromagnetism in dilute Fermi gases is predicted to emerge at values of the gas parameter where second-order perturbation theory is not accurate enough to properly describe the system. We have revisited perturbation theory for SU(N) fermions and derived its generalization up to third order both in terms of the gas parameter and the polarization. Our results agree satisfactorily with quantum Monte Carlo results for hard-sphere and soft-sphere potentials for $S = 1/2$. Although the nature of the phase transition depends on the interaction potential, we find that for a hard-sphere potential a phase transition is guaranteed to occur. While for $S= 1/2$ we observe a quasi-continuous transition, for spins $3/2$ and $5/2$, a first-order phase transition is found. For larger spins, a double transition (combination of continuous and discontinuous) occurs. The critical density reduces drastically when the spin increases, making the phase transition more accessible to experiments with ultracold dilute Fermi gases. Estimations for Fermi gases of Yb and Sr with spin $5/2$ and $9/2$, respectively, are reported.
