EXACTLY SOLVABLE FIELD-THEORY OF D=0 CLOSED AND OPEN STRINGS

The field theory of interacting closed and open strings is solved using the equivalence with a random matrix model. The partition function of the theory is given in the scaling limit by an universal function of the renormalized cosmological constant Λ, mass M at the ends of the open string, and couplings G and Γ for the closed- and open-string interactions, correspondingly. Its second derivative in Λ obeys an ordinary differential equation of fourth degree. © 1990.