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


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).

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Description/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 ReA2=(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 ImA2=-(6.83±0.51stat±1.30syst)10-13  GeV. Moreover combining our result for ImA2 with experimental values of ReA2, ReA0, and ϵ′/ϵ, we obtain the following value for the unknown ratio ImA0/ReA0 within the standard model: ImA0/ReA0=-1.63(19)stat(20)syst×10-4. One consequence of these results is that the contribution from ImA2 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.

Item Type: Article
ISSNs: 0031-9007 (print)
1079-7114 (electronic)
Subjects: Q Science > QC Physics
Divisions: Faculty of Physical Sciences and Engineering > Physics and Astronomy > Theoretical Partical Physics Group
ePrint ID: 339270
Date Deposited: 28 May 2012 13:09
Last Modified: 27 Mar 2014 20:22
URI: http://eprints.soton.ac.uk/id/eprint/339270

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