∆I= 1/2 Rule andB̂K: 2014

Buras, Andrzej J.

doi:10.1051/epjconf/20148000001

Cited by 3 publications

(6 citation statements)

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“…While the lattice QCD approach has a better control over the errors than our approach, it does not provide the physical picture of the dynamics behind the obtained numerical results. This is in particular seen in the case of the ∆I = 1/2 rule where our analytic approach offers a very simple picture of the dynamics behind this rule, as summarized again in [16,17].…”

Section: Introductionmentioning

confidence: 73%

“…But already in the second half of the 1980s, we have developed an approach to K 0 −K 0 mixing and non-leptonic K-meson decays [7][8][9][10][11] based on the dual representation of QCD as a theory of weakly interacting mesons for large N , where N is the number of colours [12][13][14][15]. The most recent results from our approach can be found in [16,17]. This approach provided, in particular, first results within QCD for the amplitudes ReA 0 and ReA 2 in the ballpark of experimental values [10].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Upper bounds on ε′/ε parameters B 6 (1/2) and B 8 (3/2) from large N QCD and other news

Buras¹,

Gérard

2015

J. High Energ. Phys.

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149

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Section: Introductionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Upper bounds on ε′/ε parameters B 6 (1/2) and B 8 (3/2) from large N QCD and other news

Buras¹,

Gérard

2015

J. High Energ. Phys.

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149

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“…In this limit there are no QCD corrections to the Wilson coefficient of the current-current operator Q 2 = (su) V −A (ūd) V −A representing a simple tree-level W ± exchange and the relevant hadronic matrix elements of this operator can be calculated exactly in terms of pion decay constant F π and the masses m K and m π by just factorizing the operator matrix element into the product of matrix elements of quark currents. One finds then [2] ReA 0 = 3.59 × 10 −8 GeV, ReA 2 = 2.54 × 10 −8 GeV , R = √ 2 (3) in plain disagreement with the data in (1) and (2). It should be emphasized that the explanation of the missing enhancement factor of 15.8 in R through some dynamics must simultaneously give the correct values for ReA 0 and ReA 2 .…”

Section: Introductionmentioning

confidence: 77%

“…Therefore I changed my strategy and concentrated since 2014 [2], with few exceptions, on Kaon flavour physics. A series of reviews on our work appeared in [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

The Return of Kaon Flavour Physics

Buras¹

2018

Acta Phys. Pol. B

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Kaon flavour physics has played in the 1960s and 1970s a very important role in the construction of the Standard Model (SM) and in the 1980s and 1990s in SM tests with the help of CP violation in K L → ππ decays represented by ε K and the ratio ε /ε. In this millennium this role has been taken over by B s,d and D mesons. However there is no doubt that in the coming years we will witness the return of kaon flavour physics with the highlights being the measurements of the theoretically clean branching ratios for the rare decays K + → π + νν and K L → π 0 νν and the improved SM predictions for the ratio ε /ε, for ε K and the K 0 −K 0 mixing mass difference ∆M K . Theoretical progress on the decays K L,S → µ + µ − and K L → π 0 + − is also expected. They all are very sensitive to new physics (NP) contributions and the correlations between them should help us to identify new dynamics at very short distance scales. These studies will be enriched when theory on the K → ππ isospin amplitudes ReA 0 and ReA 2 improves. This talk summarizes several aspects of this exciting field. In particular we emphasize the role of the Dual QCD approach in getting the insight into the numerical Lattice QCD results on K 0 −K 0 mixing and K → ππ decays.

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“…but also this result indicates that SM has some problems in reproducing the data. As the bound in (4.6) plays a significant role in the conclusion that NP could be at work in ε /ε, let me ask sceptical readers to have a look at [69,70] where other successes of the large N approach [66,67,[71][72][73][74] are summarized. In particular those related to the ∆I = 1/2 rule and thê B K parameter entering ε K that after almost three decades are supported by lattice QCD.…”

Section: 2)mentioning

confidence: 99%

Kaon Theory News

Buras¹

2016

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2015)

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During the last fifteen years B s,d decays, B 0 s,d −B 0 s,d mixings, related mixing induced CP-violating asymmetries S ψK S and S ψφ and CP violation in charm decays provided the dominant information about the pattern of flavour violation within the Standard Model (SM) and its extensions. K meson physics was solely represented by the CP-violating parameter ε K which by itself could still provide a very powerful constraint on new physics (NP) models but could not offer by far as much information about the pattern of flavour violation in nature as the observables in heavy meson decays. We emphasize that in the coming years K meson physics will certainly strike back through the measurements of the branching ratios of theoretically very clean decays K + → π + νν and K L → π 0 νν and improved calculations of the ratio ε /ε provided recently by lattice QCD and large N approach. Also the improved calculations of the K 0 −K 0 mass difference ∆M K could be of help in this context. We summarize the status of K + → π + νν and K L → π 0 νν within the SM and simplified NP models and update the picture of flavour violation in the Littlest Higgs model with T-parity (LHT) taking all available constraints into account. But the highlight of this talk are new results on ε /ε from lattice QCD and large N approach that give a strong indication for a new anomaly in flavour physics, this time coming from K mesons. Indeed, ε /ε within the SM is found to be significantly below the data of NA48 and KTeV collaborations. Combining lattice results on the non-perturbative parameters B(1/2) 6 and B(3/2) 8 with the assumption that the SM dynamics dominates the ∆I = 1/2 rule a 3σ anomaly in ε /ε emerges. Moreover, the recently derived upper bounds on B(1/2) 6 and B(3/2) 8 from large N approach with B(1/2) 6 ≤ B(3/2) 8 < 1, fully consistent with lattice results, increase the confidence that the found anomaly could be an important signal of NP at work. Of particular importance are the correlations between K + → π + νν, K L → π 0 νν and ε /ε. With future precise measurements of K + → π + νν and K L → π 0 νν and improved calculations of ε /ε they will surely provide powerful tools for selecting the favourite NP models. We illustrate this with the help of the LHT model and simplified models in which NP in K → πνν and ε /ε is governed by Z with flavour violating couplings or by a heavy Z .

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∆I= 1/2 Rule andB̂_K: 2014

Cited by 3 publications

References 50 publications

Upper bounds on ε′/ε parameters B 6 (1/2) and B 8 (3/2) from large N QCD and other news

Upper bounds on ε′/ε parameters B 6 (1/2) and B 8 (3/2) from large N QCD and other news

The Return of Kaon Flavour Physics

Kaon Theory News

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