Hybrid baryons via QCD sum rules

Hybrid baryons, consisting of the three light quarks and a gluon, are investigated using the QCD sum rule method. We find that the mixed condensate 〈0‖ψ¯σGψ‖0〉=${\mathit{m}}_0^2$〈0‖ψ¯ψ‖0〉 plays a dominant role in hybrid baryons in contrast with the quark condensate in the nucleon case. For the standard value of ${\mathit{m}}_0^2$=0.8 ${\mathrm{GeV}}^2$, the mass of the lowest hybrid state is found to be approximately 1.5 GeV, about the observed mass of the Roper resonance.