The self-penguin contribution to K → 2π

Bergan, A. E.; Eeg, J. O.

doi:10.1016/s0370-2693(96)01402-5

Cited by 14 publications

(10 citation statements)

References 34 publications

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“…For completeness we mention the so called self-penguin contribution to ε ′ /ε considered in ref. [13]. This contribution has not been included in any systematic NLO short-distance analysis.…”

Section: Basic Formulaementioning

confidence: 99%

at O(p4) in the chiral expansion

et al. 1998

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After updating the determination of the combination of Kobayashi-Maskawa elements Im V td V * ts according to our new estimate of the parameter B K , we study the CP -violating ratio ε ′ /ε by means of hadronic matrix elements computed to O(p 4 ) in the chiral expansion. It is the first time that this order in chiral perturbation theory is included. We also discuss the relevance of some O(p 2 ) terms that are generally neglected in the calculation of the electroweak penguin matrix elements. The most important effect of this improved analysis is the substantial reduction (20%) of the leading electroweak penguin matrix element and accordingly a reduced cancelation between the electroweak and gluon penguin contributions. The ratio ε ′ /ε is thus larger than previously estimated and its predicted value enjoys a smaller uncertainty. We find ε ′ /ε = 1.7+1.4 −1.0 × 10 −3 . Values positive and of the order of 10 −3 are therefore preferred.

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Section: Basic Formulaementioning

confidence: 99%

at O(p4) in the chiral expansion

et al. 1998

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“…(2) for the Wilson coefficient): The experimental value of the B 0 d → π 0 π 0 amplitude can be accomodated for m ∼ 220 Mev and αs π G 2 1/4 ∼ 315 MeV. -as in previous work [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. But the result is very sensitive to variations of m and αs π G 2 , as seen by loop factor Y .…”

Section: Chiral Quark Modelsmentioning

confidence: 97%

Non-leptonic decays in an extended chiral quark model

Eeg¹

2012

AIP Conference Proceedings

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We consider the color suppressed (nonfactorizable) amplitude for the decay mode $\bar{B_{d}^0} \rightarrow \pi^0 \pi^{0} $. We treat the $b$-quark in the heavy quark limit and the energetic light ($u,d,s$) quarks within a variant of Large Energy Effective Theory combined with an extension of chiral quark models. Our calculated amplitude for $\bar{B_{d}^0} \rightarrow \pi^0 \pi^{0} $ is suppressed by a factor of order $\Lambda_{QCD}/m_b$ with respect to the factorized amplitude, as it should according to QCD-factorization. Further, for reasonable values of the (model dependent) gluon condensate and the constituent quark mass, the calculated nonfactorizable amplitude for $\bar{B_{d}^0} \rightarrow \pi^0 \pi^{0} $ can easily accomodate the experimental value. Unfortunately, the color suppressed amplitude is very sensitive to the values of these model dependent parameters. Therefore fine-tuning is necessary in order to obtain an amplitude compatible with the experimental result for $\bar{B_{d}^0} \rightarrow \pi^0 \pi^{0} $.Comment: 10 pages, 6 figures. Presented at QCD@work, Lecce, Italy, june 201

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“…Other possible operators of dimension 5 or 6 exist, but give small contributions within the SM [11,12]. However, it has been stated that higher dimensional operators will become relevant [13] if the renormalization (separation) scale µ is chosen to low [8].…”

Section: The Quark Effective Lagrangian and The Wilson Coefficientsmentioning

confidence: 99%

“…The quantity M is intepreted as the constituent quark mass, appearing because of chiral symmetry breaking. Within the χQM , the matrix elements in (12,13) are evaluated to O(p 4 ) within the model. The current matrix elements of lowest order are well known, and the χQM version of these (given by divergent quark loops), are in agreement with these by construction.…”

Section: The Chiral Quark Model (χQm )mentioning

confidence: 99%

Theoretical Estimate(s) of the CP-Violating Quantity ɛ′/ɛ in K → 2π decays

Eeg

2001

Recent Developments in Particle Physics and Cosmology

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Abstract.I give a short presentation of the theoretical prediction of ε ′ /ε. Short distance and especially long distance aspects of the computation is discussed. I consentrate on the general framework and the chiral quark model approach, while other approaches are also shortly presented. Because of the intrinsic uncertainties of the long-distance computations, it is unlikely that new physics effects can be disentangled from the standard model prediction.

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The self-penguin contribution to K → 2π

Cited by 14 publications

References 34 publications

at O(p4) in the chiral expansion

at O(p4) in the chiral expansion

Non-leptonic decays in an extended chiral quark model

Theoretical Estimate(s) of the CP-Violating Quantity ɛ′/ɛ in K → 2π decays

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