The NA31 ϵ'/ϵ measurement

Barr, G.; Carosi, R.; Clarke, P. E. L.; Coward, D.; Cundy, D.; Doble, N.; Gatignon, L.; Gibson, V.; Grafström, P.; Hagelberg, R.; Kesseler, G.; Lans, J. van der; Nelson, H. N.; Wahl, H.; Black, R.; Candlin, D. J.; Muir, J.; Peach, Ken; Blümer, H.; Heinz, R.; Kleinknecht, K.; Mayer, Peter; Panzer, B.; Renk, B.; Rohrer, H.; Augé, E.; Chase, R. L.; Fournier, D.; Harrus, I.; Heusse, P.; Iconomidou-Fayard, L.; Schaffer, A.C.; Bertanza, L.; Bigi, A.; Calafiura, P.; Calvetti, M.; Casali, R.; Cerri, C.; Fantecho, R.; Galeotti, S.; Gargani, G.; Mannelli, I.; Nappi, A.; Pierazzini, G.; Becker, Christoph; Burkhardt, Hans; Holder, M.; Kreutz, A.; Quast, G.; Rost, M.; Sander, H.G.; Weihs, W.; Werthenbach, R.; Zech, G.

doi:10.1016/0920-5632(90)90526-z

Cited by 19 publications

(32 citation statements)

References 4 publications

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“…The latter diagrams play also a substantial role in the CP violating ratio ε ′ /ε. The most recent experimental results for this ratio, Re(ε ′ /ε) =    (28.0 ± 4.1) · 10 −4 (KTeV) [1] (18.5 ± 7.3) · 10 −4 (NA48) [2] (1) are in the ball park of the earlier result of the NA31 collaboration at CERN, (23.0 ± 6.5) · 10 −4 [3], and substantially higher than the value of E731 at Fermilab, (7.4 ± 5.9) · 10 −4 [4]. The grand average (according to the PDG recipe) including NA31, E731, KTeV and NA48 results, reads…”

Section: Introductionmentioning

confidence: 94%

Connections between ε′/ε and rare kaon decays in supersymmetry

et al. 2000

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We analyze the rare kaon decays K L → π 0 νν, K + → π + νν, K L → π 0 e + e − and K L → µ + µ − in conjunction with the CP violating ratio ε ′ /ε in a general class of supersymmetric models in which Z-and magnetic-penguin contributions can be substantially larger than in the Standard Model. We point out that radiative effects relate the double left-right mass insertion to the single left-left one, and that the phenomenological constraints on the latter reflect into a stringent bound on the supersymmetric contribution to the Z penguin. Using this bound, and those coming from recent data on ε ′ /ε, we find BR(, assuming the usual determination of the CKM parameters and neglecting the possibility of cancellations among different supersymmetric effects in ε ′ /ε. Larger values are possible, in principle, but rather unlikely. We stress the importance of a measurement of these three branching ratios, together with improved data and improved theory of ε ′ /ε, in order to shed light on the realization of various supersymmetric scenarios. We reemphasize that the most natural enhancement of ε ′ /ε, within supersymmetric models, comes from chromomagnetic penguins and show that in this case sizable enhancements of BR(K L → π 0 e + e − ) dir can also be expected.

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Section: Introductionmentioning

confidence: 94%

Connections between ε′/ε and rare kaon decays in supersymmetry

et al. 2000

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“…I. Our result on the form factor for the K L → γℓ + ℓ − decays seems to prefer to the data [50,51] from the K L → γe + e − decay. Therefore our values of the form factor near the threshold of the K L → γµ + µ − decay are considerably larger than the data from Ref.…”

Section: Comparison With Experimentsmentioning

confidence: 44%

“…(43) and A(K L → γγ) in Eq. (50) and using | π + |H w |K + | ≃ 1.99m 2 K × 10 −7 , we can reproduce the values of (∆m K ) pole /Γ K S in Eq. (55) and Γ(K L → γγ) expt (i) forr 0 ≃ 0.535 andα K * ≃ 2.61 with B K = 1.0, (ii) for r 0 ≃ 0.635 andα K * ≃ 2.34 with B K = 0.75 and (iii) forr 0 ≃ 0.715 andα K * ≃ 2.15 with B K = 0.50.…”

Section: Comparison With Experimentsmentioning

confidence: 86%

“…I. For experimental data on the form factor to be compared, three different ones have been known, i.e., two of them are from the γe + e − final states [50,51] and the other is from the γµ + µ − [52]. The existing data from different types of the final states are not consistent with each other near the γµ + µ − threshold as seen in Fig.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

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Nonfactorizable Contributions in Nonleptonic Weak Interactions of K Mesons

Terasaki

2001

Int. J. Mod. Phys. A

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K → ππ, K L -K S mass difference and K L → γγ ( * ) are studied systematically by decomposing their amplitude into a sum of factorizable and nonfactorizable ones. The former is calculated by using the naive factorization while the latter is assumed to be dominated by dynamical contributions of various hadron states. Non-factorizable amplitudes for the K → ππ decays are estimated by using a hard pion approximation in the infinite momentum frame. Long distance non-factorizable contributions to the K L -K S mass difference is dominated by those of pseudo scalar meson poles and ππ intermediate states. The amplitude for the K L → γγ ( * ) is given by a sum of pole contributions of pseudo scalar mesons in the s-channel and K * meson in the crossed channel.By fitting the results on the K → ππ, K L -K S mass difference and K L → γγ to the observations, values of unknown parameters involved are estimated and then, by using the resulting values of these parameters, the form factor for the Dalitz decays of K L and their rates are predicted. The results are compared with the existing data.

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“…The recent confirmation of direct CP violation in K → ππ decays is an important step in testing the Cabibbo-Kobayashi-Maskawa (CKM) mechanism for CP violation in the Standard Model. Combining the recent measurements by the KTeV and NA48 experiments [1] with earlier results from NA31 and E731 [2] gives Re (ǫ ′ /ǫ) = (2.12 ± 0.46) × 10 −3 . This value tends to be higher than theoretical predictions in the Standard Model, which center below or around 1 × 10 −3 [3].…”

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confidence: 52%

Large Delta I = 3/2 Contributions to epsilon'/epsilon in Supersymmetry

Kagan¹

1999

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We show that in supersymmetric extensions of the Standard Model gluino box diagrams can yield a large ∆I = 3 2 contribution to s → dqq FCNC processes, which may induce a sizable CP-violating contribution to the I = 2 isospin amplitude in K → ππ decays. This contribution only requires moderate mass splitting between the right-handed squarks ũR and dR , and persists for squark masses of order 1 TeV. Taking into account current bounds on Im δ LL sd from K-K mixing, the resulting contribution to ǫ ′ /ǫ could be an order of magnitude larger than the measured value.

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The NA31 ϵ'/ϵ measurement

Cited by 19 publications

References 4 publications

Connections between ε′/ε and rare kaon decays in supersymmetry

Connections between ε′/ε and rare kaon decays in supersymmetry

Nonfactorizable Contributions in Nonleptonic Weak Interactions of K Mesons

Large Delta I = 3/2 Contributions to epsilon'/epsilon in Supersymmetry

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