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First exploratory calculation of the long-distance contributions to the rare kaon decays K→πℓ+ℓ-

First exploratory calculation of the long-distance contributions to the rare kaon decays K→πℓ+ℓ-
First exploratory calculation of the long-distance contributions to the rare kaon decays K→πℓ+ℓ-
The rare decays of a kaon into a pion and a charged lepton/antilepton pair proceed via a flavor changing neutral current and therefore may only be induced beyond tree level in the Standard Model. This natural suppression makes these decays sensitive to the effects of potential new physics. The CP-conserving K→πℓ+ℓ− decay channels however are dominated by a single-photon exchange; this involves a sizeable long-distance hadronic contribution which represents the current major source of theoretical uncertainty. Here we outline our methodology for the computation of the long-distance contributions to these rare decay amplitudes using lattice QCD and present the numerical results of the first exploratory studies of these decays in which all but the disconnected diagrams are evaluated. The domain wall fermion ensembles of the RBC and UKQCD Collaborations are used, with a pion mass of Mπ∼430 MeV
and a kaon mass of MK∼625 MeV. In particular we determine the form factor, V(z), of the K+→π+ℓ+ℓ− decay from the lattice at small values of z=q2/M2K, obtaining V(z)=1.37(36), 0.68(39), 0.96(64) for the three values of z=−0.5594(12), −1.0530(34), −1.4653(82) respectively.
1550-7998
Juttner, Andreas
a90ff7c5-ae8f-4c8e-9679-b5a95b2a6247
Juttner, Andreas
a90ff7c5-ae8f-4c8e-9679-b5a95b2a6247

Juttner, Andreas (2016) First exploratory calculation of the long-distance contributions to the rare kaon decays K→πℓ+ℓ-. Physical Review D, 94. (doi:10.1103/PhysRevD.94.114516).

Record type: Article

Abstract

The rare decays of a kaon into a pion and a charged lepton/antilepton pair proceed via a flavor changing neutral current and therefore may only be induced beyond tree level in the Standard Model. This natural suppression makes these decays sensitive to the effects of potential new physics. The CP-conserving K→πℓ+ℓ− decay channels however are dominated by a single-photon exchange; this involves a sizeable long-distance hadronic contribution which represents the current major source of theoretical uncertainty. Here we outline our methodology for the computation of the long-distance contributions to these rare decay amplitudes using lattice QCD and present the numerical results of the first exploratory studies of these decays in which all but the disconnected diagrams are evaluated. The domain wall fermion ensembles of the RBC and UKQCD Collaborations are used, with a pion mass of Mπ∼430 MeV
and a kaon mass of MK∼625 MeV. In particular we determine the form factor, V(z), of the K+→π+ℓ+ℓ− decay from the lattice at small values of z=q2/M2K, obtaining V(z)=1.37(36), 0.68(39), 0.96(64) for the three values of z=−0.5594(12), −1.0530(34), −1.4653(82) respectively.

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More information

Accepted/In Press date: 28 September 2016
e-pub ahead of print date: 27 December 2016
Published date: 27 December 2016
Organisations: Theory Group

Identifiers

Local EPrints ID: 408219
URI: https://eprints.soton.ac.uk/id/eprint/408219
ISSN: 1550-7998
PURE UUID: 530c85ea-7ed5-49f0-b26f-68258d35674c

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Date deposited: 17 May 2017 04:02
Last modified: 13 Mar 2019 20:03

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