Spectrum of positive and negative parity pentaquarks, including   $SU(3)_F$ breaking
  We present the spectrum of the lightest pentaquark states of both parities and compare it with the present experimental evidence for these states. We have assumed that the main role for their mass splittings is played by the chromo-magnetic interaction. We have also kept into account the $SU(3)_F$ breaking for their contribution and for the spin orbit term. The resulting pattern is in good agreement with experiment. 
M. Abud, F. Buccella, D. Falcone, G. Ricciardi and F. Tramontano