(m, n)-strings in IIB matrix model

By adding gauge fields to the D-string classical solution, which have non-z ero contribution to commutators in continuum limit (extreme large N), we in troduced (m,n)-strings in IIB matrix model. It is found that the size of ma trices depends on the value of the electric field. The tension of these str ings appears in SL(2,Z) invariant form. The interaction for parallel and an gled strings are found in agreement with the string theory for small electr ic fields. (C) 2000 Published by Elsevier Science B.V. All rights reserved.