Holographic Wilson Loops : Quantum String Corrections

Sammanfattning: The gauge-string duality has been one of the most exciting areas in theoretical physics as it connects strongly coupled field theories with weakly interacting strings. The present thesis concerns the study of Wilson loops in this correspondence. Wilson loops are observables arising in many physical situations like the propagation of particles in gauge fields, the problem of confinement, etc. In the gauge-string correspondence these observables have a known physical description at both sides, making them ideal probes for the duality. Remarkable progress from localization has lead to predictions at all orders in the coupling for certain Wilson loop configurations in supersymmetric field theories. Being the string theory weakly interacting, in principle we can use perturbation theory to calculate the corresponding quantities. However, current string calculations have only been successful at leading order and in rare cases, next to leading order. At next to leading order the difficulties encountered include divergences, ambiguous boundary conditions, mismatch with field theory results, etc. The research presented in this thesis aims at a better understanding of these issues. The first calculation presented here concerns the Wilson line in N=2', a massive deformation of N=4 SYM. The string theory dual to this configuration is a straight line in the type IIB Pilch-Warner background. Using techniques for functional determinants, we computed the 1-loop string partition function obtaining perfect matching with localization. This constitutes a first test of the correspondence at the quantum level for nonconformal theories. The second calculation in this thesis corresponds to the ratio of the latitude and circular Wilson loops in AdS5xS5. An IR anomaly related to the singular nature of the conformal gauge is shown to solve previously found discrepancies with field theory results.