Pairing induced superconductivity in holography

Bagrov, Andrey and Meszéna, Balázs and Schalm, Koenraad and Meszena, Balazs (2014) Pairing induced superconductivity in holography. JOURNAL OF HIGH ENERGY PHYSICS, 2014 (9). ISSN 1126-6708

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Abstract

We study pairing induced superconductivity in large N strongly coupled systems at finite densityusing holography. In the weakly coupled dual gravitational theory the mechanism is conventionalBCS theory. An IR hard wall cut-off is included to ensure that we can controllably address thedynamics of a single confined Fermi surface. We address in detail the interplay between thescalar order parameter field and fermion pairing. Adding an explicitly dynamical scalar operatorwith the same quantum numbers as the fermion-pair, the theory experiences a BCS/BEC crossovercontrolled by the relative scaling dimensions. We find the novel result that this BCS/BEC crossoverexposes resonances in the canonical expectation value of the scalar operator. This occurs not onlywhen the scaling dimension is degenerate with the Cooper pair, but also with that of higherderivative paired operators. We speculate that a proper definition of the order parameter whichtakes mixing with these operators into account stays finite nevertheless.

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