Effective Lagrangians and Infinity Cancellations for Open String Theories

Citation

Cline, James Michael (1988) Effective Lagrangians and Infinity Cancellations for Open String Theories. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/9vpf-s680. https://resolver.caltech.edu/CaltechTHESIS:01172013-140801181

Abstract

The covariant path integral formalism for theories of open and closed strings is used to study the first order of string perturbation theory beyond tree level for the closed-string states, in which the string world sheet has the topology of the disk or the real projective plane. We find that scattering amplitudes (in flat spacetime) confirm these surfaces' contribution to the low-energy effective action for the bosonic string theory, as derived by another method, demanding consistency of string propagation in background gravitational and dilaton fields (the "sigma model approach"). However, we are not able to obtain results consistent with this effective action by demanding that amplitudes in a curved background be finite; this is an unresolved puzzle. Decoupling of spurious tachyon states from the superstring S-matrix is discussed, and finiteness of amplitudes for the disk plus projective plane is demonstrated for a large class of external states, when the gauge group is SO(32).

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