Open string theory in 1+1 dimensions

We show that tree level open two dimensional string theory is exactly solvable; the solution exhibits some unusual features, and is qualitatively different from the closed case. The open string 'tachyon' S-matrix describes free fermions, which can be interpreted as the quarks at the ends of the string. These 'quarks' live naturally on a lattice in space-time. We also find an exact vacuum solution of the theory, corresponding to a charged black hole. (orig.)