Thermal field theory of bosonic gases with finite-range effective interaction

Year: 2017

Authors: Cappellaro A., Salasnich L.

Autors Affiliation: Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy; Consorzio Nazl Interuniv Sci Fis Mat CNISM, Unita Padova, Via Marzolo 8, I-35131 Padua, Italy;‎ Consiglio Nazl Ric CNR, Ist Nazl Ott INO, Via Nello Carrara 1, I-50019 Sesto Fiorentino, Italy

Abstract: We study a dilute and ultracold Bose gas of interacting atoms by using an effective field theory which takes into account the finite-range effects of the interatomic potential. Within the formalism of functional integration from the grand canonical partition function, we derive beyond-mean-field analytical results which depend on both the scattering length and the effective range of the interaction. In particular, we calculate the equation of state of the bosonic system as a function of these interaction parameters both at zero and finite temperature including one-loop Gaussian fluctuation. In the case of zero-range effective interaction, we explicitly show that, due to quantum fluctuations, the bosonic system is thermodynamically stable only for very small values of the gas parameter. We find that a positive effective range above a critical threshold is necessary to remove the thermodynamical instability of the uniform configuration. Remarkably, also for relatively large values of the gas parameter, our finite-range results are in quite good agreement with recent zero-temperature Monte Carlo calculations obtained with hard-sphere bosons.

Journal/Review: PHYSICAL REVIEW A

Volume: 95 (3)      Pages from: 033627-1  to: 033627-6

KeyWords: BOSE-EINSTEIN CONDENSATION; HARD SPHERES; RENORMALIZATION; VORTEX; SYSTEM; ATOMS
DOI: 10.1103/PhysRevA.95.033627

Citations: 6
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