It is well known that renormalons are associated to divergences arises from the loop expansion of certain diagrams involving integration over logarithms. Although, renormalons were investigated in many QFT models, its non-perturbative nature remained unclear and the Borel resummation of the divergent expansion suffered from an infamous ambiguity. In this talk, after a brief introduction to the divergent perturbative expansions in quantum theories, I will investigate renormalon problem in the non-relativistic quantum mechanics with a potential contains 2D Dirac δ-potential, which requires renormalization, and an additional piece. We have discovered the existence of renormalon divergences for perturbative S-matrix, when the additional potential satisfies certain conditions. During the talk I will concentrate on a simple system, which gives us the full control on the calculations and allowed us to identify the non-perturbative contributions coming from the Borel resummation as the residue of the pole of the Green’s function associated to 2D Dirac δ-potential. In addition to that the Borel ambiguity is resolved by using the iε prescription, which fixed the sign of the non-perturbative contributions.
Tarih: 14 Kasım 2019 Perşembe, Saat: 16:00
Yer : MSGSÜ Fizik Bölümü, Lisansüstü Dersliği