1999/02/12 by T. Hambye, G. O. Koehler, G.O. Köhler +2 · 3 citations
Physics and Astronomy · #Amplitude #Cutoff #Hadron #High-Energy Particle Collisions Research #Lagrangian #Matrix (chemical analysis) #Meson #Order (exchange) #Particle physics theoretical and experimental studies #Pseudoscalar #Pseudoscalar meson #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.1007/s100529900084
published as Eur.Phys.J.C10:271-292,1999 · 50 pages, LaTeX, 13 eps figures
arxiv created 1999/02/12 · openalex publication_date 1999/09/01 · arxiv updated 2011/09/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present a new analysis of the Delta I = 1/2 rule in K --> pi pi decays and the BK parameter. We use the 1/Nc expansion within the effective chiral lagrangian for pseudoscalar mesons and compute the hadronic matrix elements at leading and next-to-leading order in the chiral and the 1/Nc expansions. Numerically, our calculation reproduces the dominant Delta I = 1/2 K --> pi pi amplitude. Our result depends only moderately on the choice of the cutoff scale in the chiral loops. The Delta I = 3/2 amplitude emerges sufficiently suppressed but shows a significant dependence on the cutoff. The BK parameter turns out to be smaller than the value previously obtained in the 1/Nc approach. It also shows a significant dependence on the choice of the cutoff scale. Our results indicate that corrections from higher order terms and/or higher resonances are large for the Delta I = 3/2 K --> pi pi amplitude and the (|Delta S| = 2) K0 -- anti K0 transition amplitude.