QCD_{1+1} at large N_F and N_C

Abstract

QCD in 1+1 dimensions is examined in the limit of a large number of colors and flavors. The Hamiltonian matrix is given in a Fock space spanned by 't Hooft meson states and, for the case of zero fermion mass, a submatrix is diagonalized numerically to give the low-lying spectrum as a function of $N_F /N_C $. Pair creation effects generate bound states which are complicated mixtures of components of different meson number. There are a number of nontrivial zero modes; in the massive part of the spectrum some states tend to a well-defined $N_F \gg N_C $ limit while others become unstable and disappear. The masses of most states remain remarkably constant over a large range of $N_F /N_C $.