TY  - JOUR
AU  - Donini, A.
AU  - Hernandez, P.
AU  - Pena, C.
AU  - Romero-Lopez, F.
PY  - 2020
DA  - 2020//
TI  - Dissecting the Delta I=1/2 rule at large N-c
T2  - Eur. Phys. J. C
JO  - European Physical Journal C
SP  - 638 - 12pp
VL  - 80
IS  - 7
PB  - Springer
AB  - 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.
SN  - 1434-6044
UR  - https://arxiv.org/abs/2003.10293
UR  - https://doi.org/10.1140/epjc/s10052-020-8192-3
DO  - 10.1140/epjc/s10052-020-8192-3
LA  - English
N1  - WOS:000552393200003
ID  - Donini_etal2020
ER  -