Worldsheet contributions to instantons in string effective field theories

Abstract

The D-instantons in [Formula: see text] theory can contribute to the string effective action. The relation with the D-instanton term in Type IIB string theory will be clarified. The equation of the scalar field is projected to the two-dimensional worldsheet, on which a [Formula: see text] conformal field theory may be formulated. The energies of primary states in a minimal [Formula: see text] theory coupled to a [Formula: see text] topological string are evaluated and compared with the particle spectrum.