Variational methods as tools in computational and constructive QFT

Giorno 21/10/2025, con inizio alle ore 15:00, presso l'Aula E del DFA, il Dr. Vasily Sazonov (Paris-Saclay University) terrà un seminario dal titolo Variational methods as tools in computational and constructive QFT.

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Abstract. The standard weak-coupling expansions in QFT are known to be asymptotic due to the improper interchange of summation and integration in their constructions. By replacing the Gaussian starting point of perturbation theory with a suitably chosen interacting model, one can instead develop convergent series representations. I will show how these ideas can be applied to the numerical computations in the lattice $\phi^4$-model, and how analogous constructions applied to the Loop Vertex Expansion (LVE) enable analytic continuation of matrix-model free energies beyond the conventional analyticity domains, including across branch cuts and into regimes of arbitrarily strong coupling.