We study the lifetime of single-particle excitations in a dilute homogeneous Bose-Einstein condensate at zero temperature based on a self-consistent perturbation expansion of satisfying Goldstone's theorem and conservation laws simultaneously. It is shown that every excitation for each momentum p should have a finite lifetime proportional to the inverse a~(-1) of the s-wave scattering length a, instead of a~(-2) for the normal state, due to a new class of Feynman diagrams for the self-energy that emerges upon condensation. We calculate the lifetime as a function of |p| approximately.
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机译：我们基于满足Goldstone定理和守恒律的自洽扰动展开，研究了零均质Bose-Einstein稀稀释均质凝析物中单粒子激发的寿命。结果表明，每个动量p的激发应具有与s波散射长度a的倒数a〜（-1）成正比的有限寿命，而不是正常状态下的a〜（-2），这是由于a凝聚后出现的自能的新一类费曼图。我们根据| p |计算寿命。约。
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