KL → π0νν̄ beyond the Standard Model

Yuval Grossman; Yosef Nir

doi:10.1016/S0370-2693(97)00210-4

K_L → π⁰νν̄ beyond the Standard Model

Yuval Grossman, Yosef Nir

Research output: Contribution to journal › Article › peer-review

276 Scopus citations

Abstract

We analyze the decay K_L → π⁰νν̄ in a model independent way. If lepton flavor is conserved the final state is (to a good approximation) purely CP even. In that case this decay mode goes mainly through CP violating interference between mixing and decay. Consequently, a theoretically clean relation between the measured rate and electroweak parameters holds in any given model. Specifically, Γ (K_L → π⁰νν̄)/Γ (K⁺ → π⁺νν̄) = sin² θ (up to known isospin corrections), where θ is the relative CP violating phase between the K - K̄ mixing amplitude and the s → dνν̄ dececay amplitude. The experimental bound on BR(K⁺ → π⁺νν̄) provides a model independent upper bound: BR(K_L → π⁰νν̄) < 1.1 × 10^-8. In models with lepton flavor violation, the final state is not necessarily a CP eigenstate. Then CP conserving contributions can dominate the decay rate.

Original language	English
Pages (from-to)	163-168
Number of pages	6
Journal	Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume	398
Issue number	1-2
DOIs	https://doi.org/10.1016/S0370-2693(97)00210-4
State	Published - 10 Apr 1997
Externally published	Yes

Bibliographical note

Funding Information:
We thank Andrzej Buras for asking the questions that led to this work. We thank Francesca Borzumati, Gerhard Buchalla, Gino Isidori, Riccardo Rattazzi, Adam Schwimmer and Mihir Worah for helpful discussions. Y.G. is supported by the Department of Energy under contract DE-AC03-76SF005 15. Y.N. is supported in part by the United States-Israel Binational Science Foundation (BSF), by the Israel Science Foundation, and by the Minerva Foundation (Munich).

Funding Information:
* Research supported by the Department DE-ACO3-76SFOOS 15.

Funding

We thank Andrzej Buras for asking the questions that led to this work. We thank Francesca Borzumati, Gerhard Buchalla, Gino Isidori, Riccardo Rattazzi, Adam Schwimmer and Mihir Worah for helpful discussions. Y.G. is supported by the Department of Energy under contract DE-AC03-76SF005 15. Y.N. is supported in part by the United States-Israel Binational Science Foundation (BSF), by the Israel Science Foundation, and by the Minerva Foundation (Munich). * Research supported by the Department DE-ACO3-76SFOOS 15.

Funders	Funder number
Department	DE-ACO3-76SFOOS 15
U.S. Department of Energy	DE-AC03-76SF005 15
Bonfils-Stanton Foundation
Minerva Foundation
United States-Israel Binational Science Foundation
Israel Science Foundation

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10.1016/S0370-2693(97)00210-4

Cite this

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title = "KL → π0ν{\=ν} beyond the Standard Model",

abstract = "We analyze the decay KL → π0ν{\=ν} in a model independent way. If lepton flavor is conserved the final state is (to a good approximation) purely CP even. In that case this decay mode goes mainly through CP violating interference between mixing and decay. Consequently, a theoretically clean relation between the measured rate and electroweak parameters holds in any given model. Specifically, Γ (KL → π0ν{\=ν})/Γ (K+ → π+ν{\=ν}) = sin2 θ (up to known isospin corrections), where θ is the relative CP violating phase between the K - {\=K} mixing amplitude and the s → dν{\=ν} dececay amplitude. The experimental bound on BR(K+ → π+ν{\=ν}) provides a model independent upper bound: BR(KL → π0ν{\=ν}) < 1.1 × 10-8. In models with lepton flavor violation, the final state is not necessarily a CP eigenstate. Then CP conserving contributions can dominate the decay rate.",

author = "Yuval Grossman and Yosef Nir",

note = "Funding Information: We thank Andrzej Buras for asking the questions that led to this work. We thank Francesca Borzumati, Gerhard Buchalla, Gino Isidori, Riccardo Rattazzi, Adam Schwimmer and Mihir Worah for helpful discussions. Y.G. is supported by the Department of Energy under contract DE-AC03-76SF005 15. Y.N. is supported in part by the United States-Israel Binational Science Foundation (BSF), by the Israel Science Foundation, and by the Minerva Foundation (Munich). Funding Information: * Research supported by the Department DE-ACO3-76SFOOS 15.",

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AU - Nir, Yosef

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N2 - We analyze the decay KL → π0νν̄ in a model independent way. If lepton flavor is conserved the final state is (to a good approximation) purely CP even. In that case this decay mode goes mainly through CP violating interference between mixing and decay. Consequently, a theoretically clean relation between the measured rate and electroweak parameters holds in any given model. Specifically, Γ (KL → π0νν̄)/Γ (K+ → π+νν̄) = sin2 θ (up to known isospin corrections), where θ is the relative CP violating phase between the K - K̄ mixing amplitude and the s → dνν̄ dececay amplitude. The experimental bound on BR(K+ → π+νν̄) provides a model independent upper bound: BR(KL → π0νν̄) < 1.1 × 10-8. In models with lepton flavor violation, the final state is not necessarily a CP eigenstate. Then CP conserving contributions can dominate the decay rate.

AB - We analyze the decay KL → π0νν̄ in a model independent way. If lepton flavor is conserved the final state is (to a good approximation) purely CP even. In that case this decay mode goes mainly through CP violating interference between mixing and decay. Consequently, a theoretically clean relation between the measured rate and electroweak parameters holds in any given model. Specifically, Γ (KL → π0νν̄)/Γ (K+ → π+νν̄) = sin2 θ (up to known isospin corrections), where θ is the relative CP violating phase between the K - K̄ mixing amplitude and the s → dνν̄ dececay amplitude. The experimental bound on BR(K+ → π+νν̄) provides a model independent upper bound: BR(KL → π0νν̄) < 1.1 × 10-8. In models with lepton flavor violation, the final state is not necessarily a CP eigenstate. Then CP conserving contributions can dominate the decay rate.

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