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arXiv · 1608.08402

Controlling Feynman diagrammatic expansions: physical nature of the pseudo gap in the two-dimensional Hubbard model

Wei Wu·Michel Ferrero·Antoine Georges·Evgeny Kozik
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Abstract

We introduce a method for summing Feynman's perturbation series based on diagrammatic Monte Carlo that significantly improves its convergence properties. This allows us to investigate in a controllable manner the pseudogap regime of the Hubbard model and to study the nodal/antinodal dichotomy at low doping and intermediate coupling. Marked differences from the weak coupling scenario are manifest, such as a higher degree of incoherence at the antinodes than at the `hot spots'. Our results show that the pseudogap and reduction of quasiparticle coherence at the antinode is due to antiferromagnetic spin correlations centered around the commensurate $(\pi,\pi)$ wavevector. In contrast, the dominant source of scattering at the node is associated with incommensurate momentum transfer. Umklapp scattering is found to play a key role in the nodal/antinodal dichotomy.

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Wei Wu, Michel Ferrero, Antoine Georges, Evgeny Kozik. 2016-08-30. Controlling Feynman diagrammatic expansions: physical nature of the pseudo gap in the two-dimensional Hubbard model. https://doi.org/10.1103/physrevb.96.041105

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