科研之友
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摘要
This paper gives a new method of attack on the Nambu-Goldstone dynamics in spontaneously broken theories. Since the target space of the Nambu-Goldstone fields is a group coset space, their effective quantum dynamics can be naturally phrased in terms of generalized coherent-state functional integrals. As an explicit example of this line of reasoning, we construct a low-energy effective Lagrangian for the Heisenberg ferromagnet in a broken phase. The leading field configuration in the WKB approximation leads to the Landau-Lifshitz equation for quantum ferromagnet. The corresponding linearized equations allow one to identify the Nambu-Goldstone boson with a ferromagnetic magnon.
- 出版日期2012-6-22
