The BK Kaon Parameter in the 1/NC Expansion

We present work going on calculating the kaon B_K parameter in the 1/N_c expansion. The goal of this work is to analyze analytically in the presence of chiral corrections this phenomenologically very important parameter. We present the method used and preliminary results for the chiral limit value for which we get hat B_{KX = 0.29 ± 0.15 . We also give some analytical indications of why the large Nc prediction of hat BK = 3/4 may have small 1/Nc corrections in the real case.}