Riccardo Rossi (Simons Foundation, Flatiron, New-York)

High-order renormalized perturbative approach for strongly-correlated fermions

(Séminaire zoom: https://zoom.us/j/96903025813?pwd=SjNLV2FERjJFcjlRY1crY0FFL0Q0dz09 ID de réunion : 969 0302 5813 Code secret : 007425 )

In this talk I show how perturbation theory can be turned into a viable computational approach for physical systems afflicted by the fermionic sign problem. This is accomplished by designing new numerical approaches to reach arbitrary-high orders for the bare [1] and the renormalized [2] expansion. I discuss the results obtained for the doped square-lattice Hubbard model in the pseudogap regime, and in frustrated lattices. Finally, I present the first unbiased diagrammatic computation in a broken-symmetry phase by discussing the s-wave superfluid transition in the spin-polarized cubic-lattice attractive Hubbard model.

[2] RR, Simkovic, Ferrero, EPL 132, 11001 (2020)