ΔI= 1/2 and epsilon′/epsilon in large-NcQCD

2003/05/13 by Thomas Hambye, T. Hambye, S. Peris +3 · 4 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Mathematical physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #hep-lat #hep-ph

paper · pdf · doi:10.1088/1126-6708/2003/05/027

published as JHEP 0305:027,2003 · 25 pages, 8 figures, LaTeX file. Couple of references added

openalex publication_date 2003/05/13 · arxiv created 2003/05/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We present new results for the matrix elements of the Q₆ and Q₄ penguin operators, evaluated in a large-Nc approach which incorporates important O(N_c²(n_f)/(N_c)) unfactorized contributions. Our approach shows analytic matching between short- and long-distance scale dependences within dimensional renormalization schemes, such as MS-bar. Numerically, we find that there is a large positive contribution to the Delta I =1/2 matrix element of Q₆ and hence to the direct CP-violation parameter epsilon'/epsilon. We also present results for the Delta I = 1/2 rule in K -> pi pi amplitudes, which incorporate the related and important ``eye-diagram'' contributions of O(N_c²(1)/(N_c)) from the Q₂ operator (i.e. the penguin-like contraction). The results lead to an enhancement of the Delta I = 1/2 effective coupling. The origin of the large unfactorized contributions which we find is discussed in terms of the relevant scales of the problem.

Citations

• The Standard Model prediction for ε′/ε
• Weak Hamiltonian, CP Violation and Rare Decays
• Electroweak Penguins and Large Nc
• K0– mixing in the 1/Nc expansion
• Weak K-amplitudes in the chiral and
• New analysis of the Δ I = 1/2 rule in kaon decays and the B_K parameter
• Weak matrix elements for CP violation
• Long-distance dimension-eight operators inBK
• Chiral perturbation theory: Expansions in the mass of the strange quark
• A planar diagram theory for strong interactions
• Matching the electroweak penguins Q7,Q8 and spectral correlators

Cited by

• Four-point correlator constraints on electromagnetic chiral parameters and resonance effective Lagrangians
• Study of kaon decay to two pions
• Rare kaon decays revisited
• Anatomy of prominent B and K decays and signatures of CP-violating new physics in the electroweak penguin sector