2003/06/30 by Andrzej J. Buras, Matthias Jamin · 2 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ex #hep-lat #hep-ph
paper · pdf · doi:10.1088/1126-6708/2004/01/048
published as JHEP 0401 (2004) 048 · 18 pages, 1 eps figure, version to appear in JHEP
arxiv created 2004/01/22 · openalex publication_date 2004/01/27 · arxiv updated 2009/11/30 · openalex created_date 2022/08/13 · openalex updated_date 2026/06/19
During the last four years several parameters relevant for the analysis of the CP-violating ratio epsilon'/epsilon improved and/or changed significantly. In particular, the experimental value of epsilon'/epsilon and the strange quark mass decreased, the uncertainty in the CKM factor has been reduced, and for a value of the hadronic matrix element of the dominant electroweak penguin operator Q8, some consensus has been reached among several theory groups. In view of this situation, ten years after the first analyses of epsilon'/epsilon at the next-to-leading order, we reconsider the analysis of epsilon'/epsilon within the SM and investigate what can be said about the hadronic Q6 matrix element of the dominant QCD penguin operator on the basis of the present experimental value of epsilon'/epsilon and todays values of all other parameters. Employing a conservative range for the reduced electroweak penguin matrix element R8=1.0+-0.2 from lattice QCD, and present values for all other input parameters, on the basis of the current world average for epsilon'/epsilon, we obtain the reduced hadronic matrix element of the dominant QCD penguin operator R6=1.23+-0.16 implying <Q6>0NDR(mc) ~ -0.8 <Q8>2NDR(mc). We compare these results with those obtained in large-Nc approaches in which generally R6 ~ R8 and <Q6>0NDR(mc) is chirally suppressed relatively to <Q8>2NDR(mc). We present the correlation between R6 and R8 that is implied by the data on epsilon'/epsilon provided new physics contributions to epsilon'/epsilon can be neglected.