Origin and fate of the pseudogap in the Hubbard model

We investigate the doped two-dimensional Hubbard model at finite temperature using diagrammatic Monte Carlo calculations. The results we obtain are controlled and, importantly, address the infinite-size limit of the model therefore yielding physical quantities with arbitrary momentum resolution. This allows us to carefully investigate the consequences of electronic correlations on the spectral properties, with an emphasis on the Fermi surface topology and the pseudogap regime. We show that the quasiparticle excitations are selectively destroyed near the antinodal regions because of the onset of magnetic correlations, both at weak coupling when the correlation length is large, and at strong coupling when it is shorter. We discuss how a modified spin-fluctuation theory can account for these results. Finally, we investigate the fate of the pseudogap regime as temperature is lowerer. We show that it is unstable and eventually turns into an ordered stripe phase, as found by ground-state methods.