The Return of Kaon Flavour Physics

Buras, Andrzej J.

doi:10.5506/aphyspolb.49.1043

Cited by 21 publications

(29 citation statements)

References 230 publications

(451 reference statements)

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“…Past successes of this approach have been recently reviewed in [2]. In particular the non-perturbative parameterB K has been predicted already in 1987 to be close to its large N value 0.75 and found in 2014 with higher precision to beB K = 0.73 ± 0.02 [20] in a very good agreement with the present FLAG averageB K = 0.762 ± 0.010 [46].…”

Section: Past Successes Of Dqcdsupporting

confidence: 73%

“…In the case of a SM singlet Z mixing with the Z 0 , sizable Z 0 -mediated contributions are disfavoured by electroweak precision tests. Yet, as discussed in [2] and in references given there, also such models could play some role in understanding the role of NP in ε /ε. This is in particular the case of model with vector-like quarks [56].…”

Section: Lessons From the Smeft Analysis Of ε /εmentioning

confidence: 98%

“…Various aspects of these decays and observables are reviewed at length in [1,2]. Here we will concentrate our discussion on ε /ε that has been measured already many years ago with the experimental world average from NA48 [3] and KTeV [4,5] collaborations given by (ε /ε) exp = (16.6 ± 2.3) × 10 −4 .…”

Section: Introductionmentioning

confidence: 99%

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The Dual QCD @ Work: 2018

Buras

2018

EPJ Web Conf.

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The Dual QCD (DQCD) framework, based on the ideas of 't Hooft and Witten, and developed by Bill Bardeen, Jean-Marc Gérard and myself in the 1980s is not QCD, a theory of quarks and gluons, but a successful low energy approximation of it when applied to K → ππ decays and K 0 −K 0 mixing. After years of silence, starting with 2014, this framework has been further developed in order to improve the SM prediction for the ratio ε /ε, the ∆I = 1/2 rule andB K . Most importantly, this year it has been used for the calculation of all K → ππ hadronic matrix elements of BSM operators which opened the road for the general study of ε /ε in the context of the SM effective theory (SMEFT). This talk summarizes briefly the past successes of this framework and discusses recent developments which lead to a master formula for ε /ε valid in any extension of the SM. This formula should facilitate the search for new physics responsible for the ε /ε anomaly hinted by 2015 results from lattice QCD and DQCD.• The analysis of ε /ε by the RBC-UKQCD collaboration based on their lattice QCD calculation of K → ππ matrix elements [6,7], as well as the analyses performed in [8,9] that are based on the same matrix elements but also include isospin breaking effects, find ε /ε in the ballpark of (1 − 2) × 10 −4 . This is by one order of magnitude below the data, but with an error in the ballpark of 5 × 10 −4 . Consequently, based on these analyses, one can talk about an ε /ε anomaly of at most 3σ.

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Section: Past Successes Of Dqcdsupporting

confidence: 73%

Section: Lessons From the Smeft Analysis Of ε /εmentioning

confidence: 98%

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The Dual QCD @ Work: 2018

Buras

2018

EPJ Web Conf.

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“…Recent computations of I = 0 pion-pion scattering which suffer the same problems appear promising. If improved theory results for Re( / ), expected in the near future, signal new physics, there are several interesting beyond the Standard Model scenarios that can shed light on its nature (see [99] for an up to date discussion). An important point is that in typical BSM models either QCD or EW penguin operators dominate, but not both [100].…”

Section: K → ππ Decaysmentioning

confidence: 99%

Opportunities for Lattice QCD in quark and lepton flavor physics

et al. 2019

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This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for lattice QCD in quark and lepton flavor physics. New data generated at Belle II, LHCb, BES III, NA62, KOTO, and Fermilab E989, combined with precise calculations of the relevant hadronic physics, may reveal what lies beyond the Standard Model. We outline a path toward improvements of the precision of existing lattice-QCD calculations and discuss groundbreaking new methods that allow lattice QCD to access new observables.

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“…Consequently, values above 2 × 10 −3 , that appear to be rather unrealistic from the point of view of DQCD and lattice results of 2015, are not excluded in this approach. 1 Recently progress towards an improved estimate of ε /ε in the SM has been made:…”

Section: Introductionmentioning

confidence: 99%

On the importance of NNLO QCD and isospin-breaking corrections in $$\varepsilon '/\varepsilon $$

2019

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Following the 1999 analysis of Gambino, Haisch and one of us, we stress that all the recent NLO analyses of ε /ε in the Standard Model (SM) suffer from the renormalization scheme dependence present in the electroweak penguin contributions as well as from scale uncertainties in them related to the matching scale µ W and in particular to µ t in m t (µ t ). We also reemphasize the important role of isospin-breaking and QED effects in the evaluation of ε /ε. Omitting all these effects, as done in the 2015 analysis by RBC-UKQCD collaboration, and choosing as an example the QCD penguin (Q 6 ) and electroweak penguin (Q 8 ) parameters B(1/2) 6 and B(3/2) 8 to be B(1/2) 6 = 0.80 ± 0.08 and B(3/2) 8 2. Use the result for isospin-breaking and QED corrections from [18], which are compatible with the ones obtained already 30 years ago in [36].3. Use the NNLO QCD contributions to EWP in [34] in order to reduce the unphysical renormalization scheme and scale dependences.4. Include NNLO QCD contributions to QCDP from [19,20] in order to reduce left-over renormalization scale uncertainties.In view of the fact that meson evolution and the remaining three effects tend to suppress ε /ε, the expectation based on DQCD approach in [14] that ε /ε ≈ (5 ± 2) × 10 −4 in the SM could indeed be confirmed one day by LQCD.

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The Return of Kaon Flavour Physics

Cited by 21 publications

References 230 publications

The Dual QCD @ Work: 2018

The Dual QCD @ Work: 2018

Opportunities for Lattice QCD in quark and lepton flavor physics

On the importance of NNLO QCD and isospin-breaking corrections in $$\varepsilon '/\varepsilon $$

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