We study the problem of finding the beta functions, and the associated spacetime effective action, for interacting open and closed strings propagating in background fields. String loop divergences play a crucial role in this problem. Cancelling them against sigma model divergences gives a consistent set of loop-corrected beta functions, which can be derived from a simple generalization of the string-tree-level effective action. This suggests the existence of new string theories which are conformally invariant only after all world sheets have been summed.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics