Long Strings and Chiral Non-Singlets in Matrix Quantum Mechanics

We study the non-singlet sectors of Matrix Quantum Mechanics in application to two-dimensional string theory. We use the chiral formalism, which operates directly with incoming and outgoing asymptotic states, related by a scattering operator. We give a prescription for evaluating the tree level non-singlet scattering amplitudes given the profile of the Fermi sea. In the case of a stationary Fermi sea our general formula for the adjoint representation reproduces Maldacena's scattering amplitude for a long string to go in and come back to infinity.