2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/42702We estimate the mass of the pentaquark state with QCD sum rules and find that pentaquark states with isospin $I=0, 1, 2$ lie close to each other around $(1.55\pm 0.15)$ GeV. The experimentally observed baryon resonance $Θ^+ (1540)$ with $S=+1$ can be consistently identified as a pentaquark state if its $J^P={1\over 2}^-$. Such a state is expected in QCD. If its parity is positive, this pentaquark state is really exotic. Now the outstanding issue is to determine its quantum numbers experimentally.High Energy Physics - PhenomenologyHigh Energy Physics - ExperimentNuclear ExperimentNuclear Theorytext