Power corrections to the CP-violation parameter εK

A bstract We present the calculation of the short-distance power corrections to the CP-violation parameter ε K coming from dimension-8 operators in the ∆ S = 2 effective Hamiltonian. A first estimate of this contribution, obtained for large- N c and in the chiral limit, was provided in ref. [ 1 ]. Here we evaluate and include the O m K 2 / m c 2 and O Λ QCD 2 / m c 2 contributions that, a priori, could induce O (1) corrections to previous estimates, as m K is numerically of order Λ QCD . Our computation shows that there are several dimension-8 operators besides the one considered before. Their effect on ε K , however, accidentally cancels out to a large extent, leaving the final correction at the level of 1%.