On the Spectrum of QCD(1+1) with SU(N_c) Currents

Extending previous work, we calculate the fermionic spectrum of two-dimensional QCD (QCD 2 ) in the formulation with SU ( N c ) currents. Together with the results in the bosonic sector this allows to address the as yet unresolved task of finding the single-particle states of this theory as a function of the ratio of the numbers of flavors and colors, λ = N f /N c , anew. We construct the Hamiltonian matrix in DLCQ formulation as an algebraic function of the harmonic resolution K and the continuous parameter λ in the Veneziano limit. We find that the fermion momentum is a function of λ in the discrete approach. A universality, existing only in two dimensions, dictates that the well-known ’t Hooft and large N f spectra be reproduced in the limits λ → 0 and ∞ , which we confirm. We identify their single-particle content which is surprisingly the same as in the bosonic sectors. All multi-particle states are classified in terms of their constituents. These findings allow for an identification of the lowest single-particles of the adjoint theory. While we do not succeed in interpreting this spectrum completely, evidence is presented for the conjecture that adjoint QCD 2 has a bosonic and an independent fermionic Regge trajectory of single-particle states.