Chiral Condensates, Q_7 and Q_8 Matrix Elements and Large-N_c QCD
  The correlation function of a $V-A$ current with a $V+A$ current is discussed within the framework of QCD in the limit of a large number of colours $N_c$. Applications to the evaluation of chiral condensates of dimension six and higher, as well as to the matrix elements of the $Q_7$ and $Q_8$ electroweak penguin operators are discussed. A critical comparison with previous determinations of the same parameters has also been made. 
Samuel Friot (CPT), David Greynat (CPT), Eduardo De Rafael (CPT)