EFFECTIVE ACTION AND MEASURE IN MATRIX MODEL OF IIB SUPERSTRINGS

We calculate an effective action and measure induced by the integratio n over the auxiliary field in the matrix model recently proposed to de scribe IIB superstrings. It is shown that the measure of integration o ver the auxiliary matrix is uniquely determined by locality and repara metrization invariance of the resulting effective action. The large-N limit of the induced measure for string coordinates is discussed in de tail. It is found to be ultralocal and, thus, is possibly irrelevant i n the continuum limit. The model of the GKM type is considered in rela tion to the effective action problem.