The spectrum of states with one current acting on the adjoint vacuum of massless QCD2

TL;DR

This paper investigates a specific class of states in massless QCD2 created by a current acting on the adjoint vacuum, analyzing their properties and eigenstate status under the mass operator, with insights into their fermionic structure.

Contribution

It introduces a new class of 'one current' states in massless QCD2 and examines their properties, including their relation to the adjoint vacuum and eigenstate status under the mass operator.

Findings

Most states are not eigenstates of M^2 outside the large N_f limit.

The adjoint vacuum is generated by a current derivative at zero momentum.

Infra-red regularization issues are identified and discussed.

Abstract

We consider a ``one current'' state, which is obtained by the application of a color current on the ``adjoint'' vacuum. This is done in $QCD_2$, with the underlying quarks in the fundamental representation. The quarks are taken to be massless, in which case the theory on the light-front can be ``currentized'', namely, formulated in terms of currents only. The adjoint vacuum is shown to be the application of a current derivative, at zero momentum, on the singlet vacuum. We apply the operator $M^2=2P^+P^-$ on these states and find that in general they are not eigenstates of $M^2$ apart from the large $N_f$ limit. Problems with infra-red regularizations are pointed out. We discuss the fermionic structure of these states.