Resummation of diagrammatic series with zero convergence radius for strongly correlated fermions

Understand

We demonstrate that summing up series of Feynman diagrams can yield unbiased accurate results for strongly-correlated fermions even when the convergence radius vanishes.

• We consider the unitary Fermi gas, a model of non-relativistic fermions in three-dimensional continuous space.
• Diagrams are built from partially-dressed or fully-dressed propagators of single particles and pairs.
• The series is resummed by a conformal-Borel transformation that incorporates the large-order behavior and the analytic structure in the Borel plane, which are found by the instanton approach.