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Linear to quadratic crossover of Cooper pair dispersion relation

S. K. Adhikari·M. Casas·A. Puente·A. Rigo·M. Fortes·M. A. Solis·M. de Llano·A. A. Valladares·O. Rojo
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Abstract

Cooper pairing is studied in three dimensions to determine its binding energy for all coupling using a general separable interfermion interaction. Also considered are Cooper pairs (CPs) with nonzero center-of-mass momentum (CMM). A coupling-independent {\it linear} term in the CMM dominates the pair excitation energy in weak coupling and/or high fermion density, while the more familiar quadratic term prevails only in the extreme low-density (i.e., vacuum) limit for any nonzero coupling. The linear-to-quadratic crossover of the CP dispersion relation is analyzed numerically, and is expected to play a central role in a model of superconductivity (and superfluidity) simultaneously accommodating a BCS condensate as well as a Bose-Einstein condensate of CP bosons.

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S. K. Adhikari, M. Casas, A. Puente, A. Rigo, M. Fortes, M. A. Solis, M. de Llano, A. A. Valladares, O. Rojo. 2000-08-31. Linear to quadratic crossover of Cooper pair dispersion relation. https://doi.org/10.1016/s0921-4534(00)01638-5

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