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Department of Mathematical Sciences

Seminar Archives

On this page you can find information about seminars in this and previous academic years, where available on the database.

Topological Solitons Seminar: Resurgence in QFT: the Principal Chiral Model

Presented by Daniele Dorigoni, DAMTP Cambridge

19 March 2014 13:00 in CM221

I will review the concept of Borel transform and resurgence behavior for the perturbative expansion of generic physical observables presenting particular examples coming from quantum mechanics and supersymmetric localized QFT. I will then discuss more in details the physical role of non-perturbative saddle points of path integrals in theories without instantons, using the example of the asymptotically free two-dimensional principal chiral model (PCM). Standard topological arguments based on homotopy considerations suggest no role for non-perturbative saddles in such theories. However, resurgence theory, unifying perturbative and non-perturbative physics, predicts the existence of several types of non-perturbative saddles associated with features of the large-order structure of perturbation theory. These points are illustrated in the PCM , where we found new non-perturbative fractionalized saddle point field configurations, and give a quantum interpretation of previously discovered `uniton' unstable classical solutions.

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