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K → (ππ)I=2 decay amplitude from lattice QCD

K → (ππ)I=2 decay amplitude from lattice QCD
K → (ππ)I=2 decay amplitude from lattice QCD
We report on the first realistic ab initio calculation of a hadronic weak decay, that of the amplitude A2 for a kaon to decay into two π mesons with isospin 2. We find Re A2 = (1.436±0.063stat±0.258syst)10-8 GeV in good agreement with the experimental result and for the hitherto unknown imaginary part we find Im A2 = -(6.83±0.51stat±1.30syst)10-13 GeV. Moreover combining our result for Im A2 with experimental values of Re A2, Re A0, and ε'/ε, we obtain the following value for the unknown ratio Im A0/Re A0 within the standard model: Im A0/Re A0 = -1.63(19)stat(20)syst×10-4. One consequence of these results is that the contribution from Im A2 to the direct CP violation parameter ε' (the so-called Electroweak Penguin contribution) is Re(ε'/ε)EWP = -(6.52±0.49stat±1.24syst)×10-4. We explain why this calculation of A2 represents a major milestone for lattice QCD and discuss the exciting prospects for a full quantitative understanding of CP violation in kaon decays.
141601-1-141601-5
Blum, T.
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Boyle, P.
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Christ, N.
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Garron, N.
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Goode, E.
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Izubuchi, T.
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Jung, C.
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Kelly, C.
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Lehner, C.
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Lightman, M.
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Liu, Q.
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Lytle, A.
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Mawhinney, R.
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Sachrajda, C.
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Soni, A.
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Sturm, C.
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Blum, T.
29e11a5b-96d3-4b8d-a17c-ec4b836ceead
Boyle, P.
a12661a4-a1da-4fdc-9207-db20087bfaba
Christ, N.
bafeb9b1-3dd1-4027-8690-1d99257b2c8e
Garron, N.
4652f982-8723-41c1-9bf7-46bc5c54c2db
Goode, E.
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Izubuchi, T.
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Jung, C.
c6d7a1c1-b894-4c10-b12f-437062bf40bd
Kelly, C.
c4345b06-5900-4597-9dbc-623dc13e6f8e
Lehner, C.
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Lightman, M.
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Liu, Q.
9c3579c5-8fa0-402b-ad8e-83f4542b1b05
Lytle, A.
098ff8c3-113f-42fe-bcbd-e8879fa44986
Mawhinney, R.
871ec3e5-7501-4c79-a815-95b147eb1907
Sachrajda, C.
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Soni, A.
7a4196ff-0f6b-429e-af54-d1036e9c433b
Sturm, C.
5ccbb81f-c09b-4b32-9871-fc6b13bfacc4

Blum, T., Boyle, P., Christ, N., Garron, N., Goode, E., Izubuchi, T., Jung, C., Kelly, C., Lehner, C., Lightman, M., Liu, Q., Lytle, A., Mawhinney, R., Sachrajda, C., Soni, A. and Sturm, C. (2012) K → (ππ)I=2 decay amplitude from lattice QCD. Physical Review Letters, 108 (14), 141601-1-141601-5. (doi:10.1103/PhysRevLett.108.141601).

Record type: Article

Abstract

We report on the first realistic ab initio calculation of a hadronic weak decay, that of the amplitude A2 for a kaon to decay into two π mesons with isospin 2. We find Re A2 = (1.436±0.063stat±0.258syst)10-8 GeV in good agreement with the experimental result and for the hitherto unknown imaginary part we find Im A2 = -(6.83±0.51stat±1.30syst)10-13 GeV. Moreover combining our result for Im A2 with experimental values of Re A2, Re A0, and ε'/ε, we obtain the following value for the unknown ratio Im A0/Re A0 within the standard model: Im A0/Re A0 = -1.63(19)stat(20)syst×10-4. One consequence of these results is that the contribution from Im A2 to the direct CP violation parameter ε' (the so-called Electroweak Penguin contribution) is Re(ε'/ε)EWP = -(6.52±0.49stat±1.24syst)×10-4. We explain why this calculation of A2 represents a major milestone for lattice QCD and discuss the exciting prospects for a full quantitative understanding of CP violation in kaon decays.

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Published date: 6 April 2012
Organisations: Theoretical Partical Physics Group

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Local EPrints ID: 339270
URI: http://eprints.soton.ac.uk/id/eprint/339270
PURE UUID: e3bff73a-16a6-47e6-8489-e62cd4f84ee5

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Date deposited: 28 May 2012 13:09
Last modified: 14 Mar 2024 11:12

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Contributors

Author: T. Blum
Author: P. Boyle
Author: N. Christ
Author: N. Garron
Author: E. Goode
Author: T. Izubuchi
Author: C. Jung
Author: C. Kelly
Author: C. Lehner
Author: M. Lightman
Author: Q. Liu
Author: A. Lytle
Author: R. Mawhinney
Author: C. Sachrajda
Author: A. Soni
Author: C. Sturm

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