Gauge Invariant Linear Response Theory of Relativistic BCS superfluids

Abstract

We develop a gauge-invariant linear response theory for relativistic Bardeen-Cooper-Schrieffer (BCS) superfluids based on a consistent-fluctuation-of-the order-parameter (CFOP) approach. The response functions from the CFOP approach satisfy important generalized Ward identities. The gauge invariance of the CFOP theory is a consequence of treating the gauge transformation and the fluctuations of the order parameter on equal footing so collective-mode effects are properly included. We demonstrate that the pole of the response functions is associated with the massless Goldstone boson. Important physical quantities such as the compressibility and superfluid density of relativistic BCS superfluids can also be inferred from our approach. We argue that the contribution from the massless Goldstone boson is crucial in obtaining a consistent expression for the compressibility.

arXiv comment33 pages, no figure

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Cited by in corpus (4)

• Theories of Linear Response in BCS Superfluids and How They Meet Fundamental Constraints
• Relation connecting thermodynamics and transport of atomic unitary Fermi superfluids
• Density and Spin Linear Response of Atomic Fermi Superfluids with Population Imbalance in BCS-BEC Crossover
• Shear Viscosity of Uniform Fermi Gases with Population Imbalance