Non-perturbative effects in string compactifications

Almost one century after the revolutionary discoveries of modern physics our understanding of nature has achieved impressive successes like the standard models of particle physics and cosmology, respectively. Fundamental questions, however, like the composition of dark matter and the origin of dark energy, which by far dominate the density of the universe, still remain a mystery. Decisive clues are expected from the experiments at the LHC at CERN, which are planned to commence in 2007. Clearly, a proper comprehension of the huge data that will become available requires a close collaboration between theory and experiment. The phenomenological implications of supersymmetry and of grand unification largely have been worked out. It is widely believed, however, that further conceptual progress will require an understanding of the quantum structure of space-time and of physics at the Planck scale. String theory plays a prominent role in this context because it is the only known (perturbatively) consistent quantum theory of gravity. Moreover, it has provided new concepts like D-branes and orbifolds that have already been taken up by phenomenologists. Current research in string theory is focused on the transfer of nonperturbative methods and results that were obtained with the help of dualities in the context of extended supersymmetry to more realistic models. An understanding of nonperturbative effects in string theory is important, in particular, for supersymmetry breaking and moduli stabilization. The proposed research is concerned with these issues and focuses on the computation of topological string amplitudes and nonperturbative superpotentials using mirror symmetry and other dualities of string, M- and F-theory and on an improved understanding of the physics of D-branes. Our work builds on methods and results that have been developed in international collaborations. It also takes up current developments like stability issue of string vacua.

Almost one century after the revolutionary discoveries of modern physics our understanding of nature has achieved impressive successes like the standard models of particle physics and cosmology, respectively. Fundamental questions, however, like the composition of dark matter and the origin of dark energy, which by far dominate the density of the universe, still remain a mystery. Decisive clues are expected from the experiments at the LHC at CERN, which are planned to commence in 2007. Clearly, a proper comprehension of the huge data that will become available requires a close collaboration between theory and experiment. The phenomenological implications of supersymmetry and of grand unification largely have been worked out. It is widely believed, however, that further conceptual progress will require an understanding of the quantum structure of space-time and of physics at the Planck scale. String theory plays a prominent role in this context because it is the only known (perturbatively) consistent quantum theory of gravity. Moreover, it has provided new concepts like D-branes and orbifolds that have already been taken up by phenomenologists. Current research in string theory is focused on the transfer of nonperturbative methods and results that were obtained with the help of dualities in the context of extended supersymmetry to more realistic models. An understanding of nonperturbative effects in string theory is important, in particular, for supersymmetry breaking and moduli stabilization. The proposed research is concerned with these issues and focuses on the computation of topological string amplitudes and nonperturbative superpotentials using mirror symmetry and other dualities of string, M- and F-theory and on an improved understanding of the physics of D-branes. Our work builds on methods and results that have been developed in international collaborations. It also takes up current developments like stability issue of string vacua.