A Comparative Study of Pentaquark Interpolating Currents
  In a diquark-diquark-antiquark picture of pentaquarks, we use two interpolating currents to calculate the mass of the recently measured $\Xi^{--}$ state in the framework of QCD sum rules. We show that, even though yielding similar values for $m_{\Xi^{--}}$ (and close to the experimental value), these currents differ from each other in what concerns the strength of the pole, convergence of the OPE and sensitivity to the continuum threshold parameter. 
R.D. Matheus, F.S. Navarra, M. Nielsen, R. Rodrigues da Silva