Correzioni istantoniche alla teoria di gauge N=2 attraverso una descrizone di stringhe aperte.

Aim of this work is to give a description of perturbative and non-perturbative contri- butions to the gauge coupling of N = 2 Supersymmetric Gauge Theories. This scope is pursued through a completely stringy methodology from an open string model. The work originated from the readings of previous works by Seiberg and Witten [1] who thoroughly solved the model for a pure SU(2) gauge theory giving the explicit computa- tion of the effective action prepotential F(a), both in perturbative and non perturbative (instantonic) contributions. The construction I show in this work is that of an R4 × T 2 × C2 /Z2 orbifold, whose annulus contributions A55 and A15 give the corrections stated above, respectively the perturbative and istantonic ones. Giving a solution to a problem classically treated in QFT shows as the greatest novelty of this project.