Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 69: Cold Atomic Gases and Superfluids

TT 69.1: Vortrag

Freitag, 5. April 2019, 09:30–09:45, H23

Diagrammatic Large-N approach to the Unitary Fermi Gas — •Gunnar Möller and Christopher R. Winterowd — University of Kent, Canterbury, UK

We explore a large-N, many fermion flavour, generalisation of the unitary Fermi gas [1] using diagrammatic Monte-Carlo techniques. Seminal work on the unitary Fermi gas problem has established a diagrammatic Monte-Carlo (diagMC) approach [2], which needs to be supplemented by exploring the high-order asymptotics of the series expansion [3]. Here, we extend the problem by introducing the inverse number of flavours as a small parameter via a large-N generalisation of the unitary gas [4,5], and we then apply diagMC. Using the Borel resummation technique developed by Rossi et al [3], we show that the convergence radius in the Borel plane is enlarged as a function of fermion flavours, thus facilitating the convergence of the series in the vicinity of the transition into the superfluid phase.

More generally, the combination of large-N field theory techniques with high-order numerical resummations opens up a new avenue for investigations of strongly interacting systems.
W. Zwerger, Springer (2012)
K. Van Houcke et al., Nat Phys 8, 366 (2012);
Van Houcke, et al., arXiv:1305.3901 (2013)
R. Rossi, et al., PRL 121, 130405 (2018)
M. Y. Veillette, et al., PRA 75, 043614 (2007)
P. Nikolic and S. Sachdev, PRA 75, 033608 (2007)