%0 Journal Article
%T Dissecting the Delta I=1/2 rule at large N-c
%A Donini, A.
%A Hernandez, P.
%A Pena, C.
%A Romero-Lopez, F.
%J European Physical Journal C
%D 2020
%V 80
%N 7
%I Springer
%@ 1434-6044
%G English
%F Donini_etal2020
%O WOS:000552393200003
%O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=4480), last updated on Mon, 10 Aug 2020 15:33:36 +0000
%X We study the scaling of kaon decay amplitudes with the number of colours, N-c, in a theory with four degenerate flavours, N-f = 4. In this scenario, two current-current operators, Q(+/-), mediate Delta S = 1 transitions, such as the two isospin amplitudes of non-leptonic kaon decays for K -> (pi pi)(I=0,2), A(0) and A(2.) In particular, we concentrate on the simpler K -> pi amplitudes, A(+/-), mediated by these two operators. A diagrammatic analysis of the large-N-c scaling of these observables is presented, which demonstrates the anticorrelation of the leading O(1/N-c) and O(N-f/N-c(2)) corrections in both amplitudes. Using our new N-f = 4 and previous quenched data, we confirm this expectation and show that these corrections are naturally large and may be at the origin of the Delta I = 1/2 rule. The evidence for the latter is indirect, based on the matching of the amplitudes to their prediction in Chiral Perturbation Theory, from which the LO low-energy couplings of the chiral weak Hamiltonian, g(+/-), can be determined. A NLO estimate of the K -> (pi pi)(I=0,2) isospin amplitudes can then be derived, which is in good agreement with the experimental value.
%R 10.1140/epjc/s10052-020-8192-3
%U https://arxiv.org/abs/2003.10293
%U https://doi.org/10.1140/epjc/s10052-020-8192-3
%P 638 - 12pp