Ground-State Energy and Condensate Density of a Dilute Bose Gas Revisited

概要

論文の詳細を見る
The ground-state energy per particle E/N and condensate density n_{0} of a dilute Bose gas are studied with a self-consistent perturbation expansion satisfying the Hugenholtz--Pines theorem and conservation laws simultaneously. A class of Feynman diagrams for the self-energy, which has escaped consideration so far, is shown to add an extra constant c_{\text{ip}}\sim O(1) to the expressions reported by Lee et al. [Phys. Rev. 106 (1957) 1135] as E/N=(2\pi\hbar^{2}an/m)[1+(128/15\sqrt{\pi}+16c_{\text{ip}}/5)\sqrt{a^{3}n}] and n_{0}/n=1-(8/3\sqrt{\pi}+c_{\text{ip}})\sqrt{a^{3}n}, where a, n, and m are are the s-wave scattering length, particle density, and particle mass, respectively. We present a couple of estimates for c_{\text{ip}}; the third-order perturbation expansion yields c_{\text{ip}}=0.412.
2013-06-15