Fermi points and the Nambu sum rule in the polar phase of $^3$He

M. A. Zubkov

doi:10.1134/s0021364017110029

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arXiv · 1705.02231

Fermi points and the Nambu sum rule in the polar phase of $^3$He

M. A. Zubkov

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Abstract

We discuss the polar phase of $^3$He, which is realized in the anisotropic aerogel. We consider it in the framework of the BCS model. In the absence of the spin - orbit interaction this model predicts the appearance of the Fermi line. However, it is topologically unstable. We demonstrate, that the spin - orbit interaction gives rise to the appearance of the two Fermi points instead of the Fermi line. In addition to the gapless Nambu - Goldstone bosons in this system the collective gapped bosonic states exist. Their gaps are calculated, and the corresponding Nambu sum rule is established.

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M. A. Zubkov. 2017-05-05. Fermi points and the Nambu sum rule in the polar phase of $^3$He. https://doi.org/10.1134/s0021364017110029

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