New QCD estimate of the kaon penguin matrix elements and epsilon'/epsilon

Abstract

Firstly, we use the recent ALEPH/OPAL data on the V-A spectral functions for fixing the continuum threshold with which the first and second Weinberg sum rules should be satisfied in the chiral limit. Then, we predict the values of the low-energy constants m_{π^+}-m_{π^0}, {L}_{10}, and test the values of the electroweak kaon penguin matrix elements <Q^{3/2}_{8,7}>_{2π} obtained from DMO--like sum rules. Secondly, we use the data on the τ-total hadronic width R_{τ,V/A} for extracting <Q_8^{3/2}_{2π}>, in the {MS}\bar scheme, and propose some new sum rules for < Q_7^{3/2}>_{2π} in the chiral limit, where the latter require more accurate data for the spectral functions near the $\tau$-mass. Thirdly, we analyze the effects to the matrix element <Q_6^{1/2}>_{2π}, of the S_2\equiv(\bar uu+\bar dd) component of the I=0 scalar meson, with its parameters fixed from QCD spectral sum rules. Our results should stimulate a further attention on the rôle of the (expected large) gluonium component of the I=0 scalar meson and of the associated operator in the K--->ππamplitude. Finally, using our previous determinations, we deduce, in the Standard Model (SM), the conservative upper bound for the CP-violating ratio: ε'/ε< (22\pm 9) 10^{-4}, which is in agreement with the present measurements.

Latex2e sources 23 pages including 1 Table + espcrc1.sty file. Version to appear in Nucl. Phys. B

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Cited by in corpus (31)

• Kaon Decays in the Standard Model
• Precise Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System
• Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System
• The Standard Model Prediction for epsilon'/epsilon
• Hints on the power corrections from current correlators in x-space
• V-A hadronic tau decays : a laboratory for the QCD vacuum
• Muon and tau anomalies updated
• Direct CP violation in $K^0\to \pi \pi$: Standard Model Status
• QCD Condensates for the Light Quark V-A Correlator
• Improved Determination of the Electroweak Penguin Contribution to epsilon'/epsilon in the Chiral Limit
• Delta I=1/2 and epsilon'/epsilon in Large-Nc QCD
• Constraining models with vector-like fermions from FCNC in K and B physics
• K^0-\bar K^0 mixing beyond the standard model and CP-violating electroweak penguins in quenched QCD with exact chiral symmetry
• Determination of the Chiral Couplings L_10 and C_87 from Semileptonic Tau Decays
• epsilon'/epsilon at the NLO: 10 Years Later
• Chiral Condensates, Q_7 and Q_8 Matrix Elements and Large-N_c QCD
• Violation of Quark-Hadron Duality and Spectral Chiral Moments in QCD
• A Critical Reassessment of Q7 and Q8 Matrix Elements
• Isospin-Violating Contributions to ${\epsilon }^{\prime }/\epsilon$
• Remarks on the hadronic matrix elements relevant to the SUSY K-Kbar mixing amplitude
• Charged Kaon K \to 3 pi CP Violating Asymmetries at NLO in CHPT
• An exploratory lattice study of DI=3/2 K -> pi pi decays at next-to-leading order in the chiral expansion
• The Strange Quark Mass, alpha_s and the Chiral Limit Electroweak Penguin Matrix Elements From Hadronic Tau Decay Data
• SU(3) analysis of four-quark operators: $K\to \pi \pi$ and vacuum matrix elements
• Matching the Electroweak Penquins Q_7 and Q_8
• Hadronic Matrix Elements for Kaons
• Electroweak penguins and SUSY K^0-\bar K^0 mixing with Neuberger quarks
• From hadronic tau decays to the chiral couplings L_10 and C_87
• Kaon weak interactions in powers of 1/Nc
• K -> pi pi Electroweak Penguins in the Chiral Limit
• Chiral loop corrections and isospin violation effects in epsilon'/epsilon