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K+ →π+ν ν ̄ decay amplitude from lattice QCD

K+ →π+ν ν ̄ decay amplitude from lattice QCD
K+ →π+ν ν ̄ decay amplitude from lattice QCD

In Ref. [1] we have presented the results of an exploratory lattice QCD computation of the long-distance contribution to the K+→π+νν̄ decay amplitude. In the present paper we describe the details of this calculation, which includes the implementation of a number of novel techniques. The K+→π+νν̄ decay amplitude is dominated by short-distance contributions which can be computed in perturbation theory with the only required nonperturbative input being the relatively well-known form factors of semileptonic kaon decays. The long-distance contributions, which are the target of this work, are expected to be of O(5%) in the branching ratio. Our study demonstrates the feasibility of lattice QCD computations of the K+→π+νν̄ decay amplitude, and in particular of the long-distance component. Though this calculation is performed on a small lattice (163×32) and at unphysical pion, kaon and charm quark masses, mπ=420 MeV, mK=563 MeV and mcMS̄(2 GeV)=863 MeV, the techniques presented in this work can readily be applied to a future realistic calculation.

2470-0010
Bai, Ziyuan
68a0d1d1-1570-4692-8d9b-9dbe4a3cdcea
Christ, Norman H.
8fdea364-b83b-4aef-8282-c02a48689d37
Feng, Xu
9c6e2a56-4165-447c-b246-71b0aea251b0
Lawson, Andrew
5c18da3e-b77e-40d1-a79c-110f8f8510c1
Portelli, Antonin
a2526d4a-144e-4095-802a-229cddb10f0f
Sachrajda, Christopher T.
0ed6568b-f52f-4314-8677-4aeeb925d6f7
RBC and UKQCD collaborations
Bai, Ziyuan
68a0d1d1-1570-4692-8d9b-9dbe4a3cdcea
Christ, Norman H.
8fdea364-b83b-4aef-8282-c02a48689d37
Feng, Xu
9c6e2a56-4165-447c-b246-71b0aea251b0
Lawson, Andrew
5c18da3e-b77e-40d1-a79c-110f8f8510c1
Portelli, Antonin
a2526d4a-144e-4095-802a-229cddb10f0f
Sachrajda, Christopher T.
0ed6568b-f52f-4314-8677-4aeeb925d6f7

Bai, Ziyuan, Christ, Norman H., Feng, Xu, Lawson, Andrew, Portelli, Antonin and Sachrajda, Christopher T. , RBC and UKQCD collaborations (2018) K+ →π+ν ν ̄ decay amplitude from lattice QCD. Physical Review D, 98 (7), [074509]. (doi:10.1103/PhysRevD.98.074509).

Record type: Article

Abstract

In Ref. [1] we have presented the results of an exploratory lattice QCD computation of the long-distance contribution to the K+→π+νν̄ decay amplitude. In the present paper we describe the details of this calculation, which includes the implementation of a number of novel techniques. The K+→π+νν̄ decay amplitude is dominated by short-distance contributions which can be computed in perturbation theory with the only required nonperturbative input being the relatively well-known form factors of semileptonic kaon decays. The long-distance contributions, which are the target of this work, are expected to be of O(5%) in the branching ratio. Our study demonstrates the feasibility of lattice QCD computations of the K+→π+νν̄ decay amplitude, and in particular of the long-distance component. Though this calculation is performed on a small lattice (163×32) and at unphysical pion, kaon and charm quark masses, mπ=420 MeV, mK=563 MeV and mcMS̄(2 GeV)=863 MeV, the techniques presented in this work can readily be applied to a future realistic calculation.

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PhysRevD.98.074509 - Version of Record
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More information

Accepted/In Press date: 1 January 2018
e-pub ahead of print date: 15 October 2018
Published date: October 2018

Identifiers

Local EPrints ID: 426493
URI: http://eprints.soton.ac.uk/id/eprint/426493
ISSN: 2470-0010
PURE UUID: 64f7bf98-c8f4-49d2-a677-a0a08779d131
ORCID for Antonin Portelli: ORCID iD orcid.org/0000-0002-6059-917X

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Date deposited: 29 Nov 2018 17:30
Last modified: 17 Dec 2019 01:38

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