D-instantons, string field theory and two dimensional string theory

A bstract In [4] Balthazar, Rodriguez and Yin (BRY) computed the one instanton contribution to two point scattering amplitude in dimensional string theory first subleading order coupling. Their analysis left undetermined constants due divergences integration over world-sheet variables, but they were fixed by numerically comparing result with that of dual matrix model. If we consider n-point amplitudes same order, there are actually four approach. We show using field can get finite unambiguous values all these constants, explicitly compute three constants. Two determined this way agree numerical BRY within accuracy analysis, third constant seems differ 1/2. also discuss a shortcut determining fourth if assume equality quantum corrected D-instanton action model instanton. This agrees BRY.