Akerblom, Nikolas (2008): Dinstantons and Effective Couplings in Intersecting Dbrane Models. Dissertation, LMU München: Faculty of Physics 

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Abstract
This thesis is concerned with two aspects of intersecting D6brane models: We treat some of the effects that are induced by E2instantons and we consider oneloop corrections to the gauge kinetic functions in the lowenergy effective field theory. We begin in chapter 1 with a general introduction covering the question why to consider string theory as a candidate theory of nature. After that, in chapter 2, we go over some topics related to field theory instantons and finally discuss the instanton generated superpotential in supersymmetric QCD (SQCD), the socalled Affleck–Dine–Seiberg (ADS) superpotential. In chapter 3 we then proceed to reproduce the ADS superpotential in an intersecting D6brane realization of SQCD as the effect of a single E2instanton. In order to do so, we first explicate the necessary formalism for calculating the E2instanton contribution to the superpotential, then construct a (local) intersecting D6brane realization of SQCD, and finally show that the formalism indeed leads to the Affleck–Dine–Seiberg superpotential. In chapter 4 we consider oneloop corrections to the gauge kinetic functions. These oneloop corrections are related quite intricately to gauge threshold corrections which we compute for intersecting D6brane models on the Z_2xZ_2 toroidal orbifold. An analysis of the formulas for calculating the E2instanton contribution to the superpotential raises the question whether this contribution is a holomorphic quantity. In chapter 5 we take up this question showing that indeed it is holomorphic. In addition, we discuss under which circumstances one can expect E2instanton corrections to the gauge kinetic functions. There follow a number of appendices, some elaborating on points touched upon in the main text, some collecting necessary formulas.
Item Type:  Theses (Dissertation, LMU Munich) 

Subjects:  500 Natural sciences and mathematics > 530 Physics 500 Natural sciences and mathematics 
Faculties:  Faculty of Physics 
Language:  English 
Date of oral examination:  15. July 2008 
1. Referee:  Blumenhagen, Ralph 
MD5 Checksum of the PDFfile:  cf217193ff296587259bd95a43bfc130 
Signature of the printed copy:  0001/UMC 17152 
ID Code:  8861 
Deposited On:  18. Aug 2008 07:08 
Last Modified:  24. Oct 2020 07:10 