Entanglement witnesses for $d \otimes d$ systems and new classes of   entangled qudit states
  We provide a new class of entanglement witnesses for $d \ot d$ systems (two qudits). Our construction generalizes the one proposed recently by Jafarizadeh et al. for $d=3$ and $d=4$ on the basis of semidefinite linear programming. Moreover, we provide a new class of PPT entangled states detected by our witnesses which generalizes well known family of states constructed by Horodecki et al. for $d=3$. 
D. Chru\'sci\'nski and A. Rutkowski
quant-ph