Event

Adrian Escobar, CRM

Monday, April 24, 2017 15:30toTuesday, April 25, 2017 16:30
Room 4336, Pavillon André-Aisenstadt, CA, QC, Montreal, 2920, Chemin de la tour, 5th floor, CA

Instanton calculus in quantum mechanics: Feynman diagrams and divergent series.

In this talk we discuss quantum mechanical problems, the double-well and sine-Gordon potentials, for which perturbation theory fails to explain physical properties even qualitatively. We then explain how non-perturbative effects can be obtained by instanton calculus. The corresponding Feynman diagrams (integrals) are used for the calculation of the tunneling amplitude up to the three-loop order. Unlike the two-loop contribution where all involved Feynman integrals are rational numbers, we will show that in the three-loop case they contain irrational contributions as well.

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