Matrix Elements of Electroweak Penguin Operators in the 1/Nc Expansion

Abstract

It is shown that the K -> pi pi matrix elements of the four-quark operator Q_7, generated by the electroweak penguin-like diagrams of the Standard Model, can be calculated to first non-trivial order in the chiral expansion and in the 1/Nc expansion. Although the resulting B factors B_7^(1/2) and B_7^(3/2) are found to depend only logarithmically on the matching scale, mu, their actual numerical values turn out to be rather sensitive to the precise choice of mu in the GeV region. We compare our results to recent numerical evaluations from lattice-QCD and to other model estimates.

10 pages, LateX, two figures (inserted). Improved comparison with the lattice results. Results unchanged

References in corpus (6)

• Weak Hamiltonian, CP Violation and Rare Decays
• Matching Long and Short Distances in Large-Nc QCD
• Patterns of Spontaneous Chiral Symmetry Breaking in the Large-Nc Limit of QCD-Like Theories
• Introduction to Lattice QCD
• The electroweak pi^+ - pi^0 mass difference and weak matrix elements in the 1/Nc expansion
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• Duality violations and spectral sum rules
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• The VV'P form factors in resonance chiral theory and the pi-eta-eta' light-by-light contribution to the muon g-2
• Direct CP violation in $K^0\to \pi \pi$: Standard Model Status
• Renormalization Group Invariant Matrix Elements of DS = 2 and DI = 3/2 Four-Fermion Operators without Quark Masses
• Final State Interactions in Kaon Decays
• Delta I=1/2 and epsilon'/epsilon in Large-Nc QCD
• Consistent high-energy constraints in the anomalous QCD sector
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• Chiral Condensates, Q_7 and Q_8 Matrix Elements and Large-N_c QCD
• The 7/11 rule: an estimate of m_rho/f_pi
• New QCD estimate of the kaon penguin matrix elements and epsilon'/epsilon
• Analysis of O(p^2) Corrections to <pi pi|Q_{7,8}|K>
• Electromagnetism in nonleptonic weak interactions
• An updated analysis of eps'/eps in the standard model with hadronic matrix elements from the chiral quark model
• A Critical Reassessment of Q7 and Q8 Matrix Elements
• Isospin-Violating Contributions to ${\epsilon }^{\prime }/\epsilon$
• Long-distance dimension-eight operators in B_K
• Combined analysis of the unitarity triangle and CP violation in the Standard Model
• Charged Kaon K \to 3 pi CP Violating Asymmetries at NLO in CHPT
• Analytic Approaches to Kaon Physics
• SU(3) analysis of four-quark operators: $K\to \pi \pi$ and vacuum matrix elements
• Minimal Hadronic Ansatz to Large-Nc QCD and Hadronic tau Decay
• epsilon'/epsilon in the Standard Model
• Chiral Limit Prediction for epsilon'/epsilon at NLO in 1/N_c
• Form factor in K+ --> pi+ pi0 gamma: interference versus direct emission
• Matching the Electroweak Penquins Q_7 and Q_8
• Hadronic Matrix Elements for Kaons
• Matrix Elements of Light Quarks
• 1/N_c and epsilon'/epsilon
• Theoretical status of epsilon'/epsilon
• Kaon weak interactions in powers of 1/Nc
• Progress in $K\to \pi \pi$ Decays
• Phenomenology From Lattice QCD
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• Unfactorizing Polychromatic Penguins
• Chiral loop corrections and isospin violation effects in epsilon'/epsilon
• Impact of Duality Violations on Spectral Sum Rule Analyses