title: K→(ππ)(I=2) decay amplitude from lattice QCD.
abstract: We report on the first realistic ab initio calculation of a hadronic weak decay, that of the amplitude A(2) for a kaon to decay into two π mesons with isospin 2. We find ReA(2)=(1.436±0.063(stat)±0.258(syst))10(-8) GeV in good agreement with the experimental result and for the hitherto unknown imaginary part we find ImA(2)=-(6.83±0.51(stat)±1.30(syst))10(-13) GeV. Moreover combining our result for ImA(2) with experimental values of ReA(2), ReA(0), and ε'/ε, we obtain the following value for the unknown ratio ImA(0)/ReA(0) within the standard model: ImA(0)/ReA(0)=-1.63(19)(stat)(20(syst)×10(-4). One consequence of these results is that the contribution from ImA(2) to the direct CP violation parameter ε' (the so-called Electroweak Penguin contribution) is Re(ε'/ε)(EWP)=-(6.52±0.49(stat)±1.24(syst))×10(-4). We explain why this calculation of A(2) represents a major milestone for lattice QCD and discuss the exciting prospects for a full quantitative understanding of CP violation in kaon decays.
authors.affiliation: Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, USA.
authors.forename: T
authors.initials: T
authors.lastname: Blum
authors.forename: P A
authors.initials: PA
authors.lastname: Boyle
authors.forename: N H
authors.initials: NH
authors.lastname: Christ
authors.forename: N
authors.initials: N
authors.lastname: Garron
authors.forename: E
authors.initials: E
authors.lastname: Goode
authors.forename: T
authors.initials: T
authors.lastname: Izubuchi
authors.forename: C
authors.initials: C
authors.lastname: Jung
authors.forename: C
authors.initials: C
authors.lastname: Kelly
authors.forename: C
authors.initials: C
authors.lastname: Lehner
authors.forename: M
authors.initials: M
authors.lastname: Lightman
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
authors.forename: A T
authors.initials: AT
authors.lastname: Lytle
authors.forename: R D
authors.initials: RD
authors.lastname: Mawhinney
authors.forename: C T
authors.initials: CT
authors.lastname: Sachrajda
authors.forename: A
authors.initials: A
authors.lastname: Soni
authors.forename: C
authors.initials: C
authors.lastname: Sturm