TY - JOUR
T1 - Shear viscosity and strong-coupling corrections in the BCS–BEC crossover regime of an ultracold Fermi gas
AU - Kagamihara, Daichi
AU - Inotani, Daisuke
AU - Ohashi, Yoji
N1 - Funding Information:
Acknowledgments We thank H. Tajima and R. Hanai for discussions. This work was supported by KiPAS project in Keio University. We also thank J. E. Thomas for informing us Ref. 67. D.K. was supported by KLL Ph.D. Program Research Grant from Keio University. Y.O. was supported by a Grant-in-Aid for Scientific Research from MEXT and JSPS in Japan (Nos. JP18K11345, JP18H05406, and JP19K03689).
Publisher Copyright:
©2019 The Physical Society of Japan
PY - 2019
Y1 - 2019
N2 - We theoretically investigate the shear viscosity η in the BCS–BEC crossover regime of an ultracold Fermi gas with a Feshbach resonance. Within the framework of the strong-coupling self-consistent T-matrix approximation, we examine how a strong pairing interaction associated with a Feshbach resonance affects this transport coefficient, in the normal state above the superfluid phase transition temperature Tc. We show that, while η diverges in both the weak-coupling BCS and strong-coupling BEC limits, it becomes small in the unitary regime. The minimum of η is obtained, not at the unitarity, but slightly in the strong-coupling BEC side. This deviation is consistent with the recent experiment on a 6Li Fermi gas. In the weak-coupling BCS regime, we also find that η exhibits anomalous temperature dependence near Tc, which is deeply related to the pseudogap phenomenon originating from strong pairing fluctuations.
AB - We theoretically investigate the shear viscosity η in the BCS–BEC crossover regime of an ultracold Fermi gas with a Feshbach resonance. Within the framework of the strong-coupling self-consistent T-matrix approximation, we examine how a strong pairing interaction associated with a Feshbach resonance affects this transport coefficient, in the normal state above the superfluid phase transition temperature Tc. We show that, while η diverges in both the weak-coupling BCS and strong-coupling BEC limits, it becomes small in the unitary regime. The minimum of η is obtained, not at the unitarity, but slightly in the strong-coupling BEC side. This deviation is consistent with the recent experiment on a 6Li Fermi gas. In the weak-coupling BCS regime, we also find that η exhibits anomalous temperature dependence near Tc, which is deeply related to the pseudogap phenomenon originating from strong pairing fluctuations.
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U2 - 10.7566/JPSJ.88.114001
DO - 10.7566/JPSJ.88.114001
M3 - Article
AN - SCOPUS:85074791141
SN - 0031-9015
VL - 88
JO - Journal of the Physical Society of Japan
JF - Journal of the Physical Society of Japan
IS - 11
M1 - 114001
ER -