Power corrections to the CP-violation parameter ε K

Abstract

Abstract 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 $$ \mathcal{O}\left({m}_K^2/{m}_c^2\right) $$ and O Λ QCD 2 / m c 2 $$ \mathcal{O}\left({\Lambda}_{\mathrm{QCD}}^2/{m}_c^2\right) $$ contributions that, a priori, could induce O $$ \mathcal{O} $$ (1) corrections to previous estimates, as m K is numerically of order ΛQCD. 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%.

Keywords

• CP violation
• Kaon Physics