Renormalons in Quantum Mechanics

Cihan Pazarbaşı
Boğaziçi Üniversitesi
Fizik Bölümü

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