Single-Particle Properties of a Strongly Interacting Bose–Fermi Mixture Above the BEC Phase Transition Temperature
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We theoretically investigate the normal state properties of a Bose–Fermi mixture with a strong attractive interaction between Fermi and Bose atoms. We extend the ordinary T-matrix approximation (TMA) with respect to Bose–Fermi pairing fluctuations, to include the Hugenholtz–Pines’ relation for all Bose Green’s functions appearing in TMA self-energy diagrams. This extension is shown to be essentially important to correctly describe the physical properties of the Bose–Fermi mixture, especially near the Bose–Einstein condensation instability. Using this improved TMA, we clarify how the formation of composite fermions affects Bose and Fermi single-particle excitation spectra, over the entire interaction strength.
KeywordsBose–Fermi mixture BEC Single-particle excitations Strong-coupling effects
D. K. thanks Keio Leading-edge Laboratory of Science and Technology (KLL) for supporting this research. This work was supported by KiPAS project in Keio University. D. I. was supported by Grant-in-Aid for Young Scientists (B) (No. 16K17773) from JSPS and R. H. was supported by Grant-in-Aid for JSPS fellows. Y. O. was supported by Grand-in-Aid for Scientific Research from MEXT and JSPS in Japan (No. 15K00178, No. 15H00840, No. 16K05503). We would like to thank H. Tajima and P. van Wyk for useful discussions.