Partially Quenched Chiral Perturbation Theory to NNLO
  This paper summarizes the recent calculations of the masses and decay constants of the pseudoscalar mesons at the two-loop level, or NNLO, in Partially Quenched Chiral Perturbation Theory (PQxPT). Possible applications include chiral extrapolations of Lattice QCD, as well as the determination of the low-energy constants (LEC:s) of QCD. 
Timo A. Lahde, Johan Bijnens, Niclas Danielsson