Two-Loop Superstrings


Duong H. Phong

Columbia University

Brandeis University

Thursday, November 1, 2001


Talk at 4:30 p.m. in 317 Goldsmith Hall

Tea at 4:00 p.m. in 300 Goldsmith Hall


Abstract:   In string theory, Feynman rules correspond to a volume form over the moduli space of Riemann surfaces. In genus > 1, the problem of determining Feynman rules had remained intractable to this day because of the presence of "supermoduli", and natural ansatze for the desired volume form had been plagued with ambiguities. In this talk, we show that these earlier problems can be traced back to gauge-fixing procedures which did not respect supersymmetry. For genus 2, we show that a proper gauge-fixing procedure produces new subtle contributions which eliminate all the earlier ambiguities: the resulting formula is independent of the choice of gauge slice. It can be rewritten in terms of modular forms. The cosmological constant is shown to vanish, and we also derive explicit formulas for the scattering of up to 4 gravitons.

Home Web page:  Alexandru I. Suciu  Created: October 26, 2001 
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