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A: Fachverband Atomphysik
A 24: Fermionic Quantum Gases II (joint session Q/A)
A 24.6: Vortrag
Mittwoch, 13. März 2024, 15:45–16:00, Aula
The role of particle-hole interactions and effective ranges in homogeneous Fermi fluids — Nikolai Kaschewski1, Axel Pelster1, and •Carlos A. R. Sá de Melo2 — 1Physics Department and Research Center OPTIMAS, RPTU Kaiserslautern-Landau, Germany — 2School of Physics, Georgia Institute of Technology, Atlanta, USA
The standard theoretical method for studying fermionic superfluidity is based on the description of interactions in terms of pairing and on the identification of a superfluid order parameter. Only particle-particle (pp) processes are included that form Cooper pairs which then perform Bose-Einstein condensation. Particle-hole (ph) processes are only sparsely considered. One example are the ph fluctuations of Gor’kov and Melik-Barkhudarov that lowers the condensation temperature [1]. On this poster, we present a self-consistent mean-field theory for BCS superfluidity that includes pp and ph processes simultaneously through a weighted partitioning of states that produce and inhibit pairing. We obtain non-perturbative corrections due to ph scattering, which require an effective range expansion [2] in order to get physical results. The theory generalizes the BCS mean field theory, makes connections to effective-range mean-field effects [3]. Our preliminary results set the stage for the simultaneous exploration of fluctuations in the pp and ph channels [1] in the BCS-BEC crossover.
[1] L.P. Gor’kov, T.K. Melik-Barkhudarov, Sov. Phys. JETP 13, 1018 (1961) [2] H. A. Bethe, Phys. Rev. 76, 38 (1949) [3] S. Mal and B. Deb, J. of Phys. B 55, 035301 (2022)
Keywords: fermionic systems; BCS; Mean-field theory; effective range