First observation and study of the K± → π0π0μ±ν decay

NA48/2 collaboration

doi:10.1007/JHEP03(2024)137

First observation and study of the K^± → π⁰π⁰μ^±ν decay

NA48/2 collaboration

Physics and Astronomy

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Abstract

The NA48/2 experiment at CERN reports the first observation of the K^± → π⁰π⁰μ^±ν decay based on a sample of 2437 candidates with 15% background contamination collected in 2003–2004. The decay branching ratio in the kinematic region of the squared dilepton mass above 0.03 GeV²/c⁴ is measured to be (0.65 ± 0.03) × 10⁻⁶. The extrapolation to the full kinematic space, using a specific model, is found to be (3.45 ± 0.16) × 10⁻⁶, in agreement with chiral perturbation theory predictions.

Original language	English
Article number	137
Number of pages	17
Journal	JHEP
Volume	2024
Issue number	3
DOIs	https://doi.org/10.1007/JHEP03(2024)137
Publication status	Published - 22 Mar 2024

Bibliographical note

Acknowledgments:
It is a pleasure to express our appreciation to the staff of the CERN laboratory and the technical staff of the participating laboratories and universities for their efforts in the operation of the experiment and data processing.

The cost of the experiment and its auxiliary systems was supported by the funding agencies of the Collaboration Institutes. We are particularly indebted to: the U.K. Particle Physics and Astronomy Research Council, grant PPA/G/O/1999/00559; the German Federal Minister for Education and Research (BMBF) under contracts 05HK1UM1/1 and 056SI74; the Austrian Ministry for Traffic and Research under the contracts GZ 616.360/2-IV and GZ 616.363/2-VIII, and by the Fonds für Wissenschaft und Forschung FWF Nr. P08929-PHY; INFN (Istituto Nazionale di Fisica Nucleare), Italy; CERN (European Organization for Nuclear Research), Switzerland; ERC (European Research Council) “KaonLepton” starting grant 336581, Europe.

Individuals have received support from: the Bulgarian National Science Fund under contract DID02-22; the Royal Society (grants UF100308, UF0758946), United Kingdom; ERC Starting Grant 336581, Europe.

Keywords

Branching fraction
Fixed Target Experiments
Rare Decay

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Cite this

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abstract = "The NA48/2 experiment at CERN reports the first observation of the K± → π0π0μ±ν decay based on a sample of 2437 candidates with 15% background contamination collected in 2003–2004. The decay branching ratio in the kinematic region of the squared dilepton mass above 0.03 GeV2/c4 is measured to be (0.65 ± 0.03) × 10−6. The extrapolation to the full kinematic space, using a specific model, is found to be (3.45 ± 0.16) × 10−6, in agreement with chiral perturbation theory predictions.",

keywords = "Branching fraction, Fixed Target Experiments, Rare Decay",

author = "{NA48/2 collaboration} and C. Lazzeroni and Slater, {M. W.} and E. Goudzovski",

note = "Acknowledgments: It is a pleasure to express our appreciation to the staff of the CERN laboratory and the technical staff of the participating laboratories and universities for their efforts in the operation of the experiment and data processing. The cost of the experiment and its auxiliary systems was supported by the funding agencies of the Collaboration Institutes. We are particularly indebted to: the U.K. Particle Physics and Astronomy Research Council, grant PPA/G/O/1999/00559; the German Federal Minister for Education and Research (BMBF) under contracts 05HK1UM1/1 and 056SI74; the Austrian Ministry for Traffic and Research under the contracts GZ 616.360/2-IV and GZ 616.363/2-VIII, and by the Fonds f{\"u}r Wissenschaft und Forschung FWF Nr. P08929-PHY; INFN (Istituto Nazionale di Fisica Nucleare), Italy; CERN (European Organization for Nuclear Research), Switzerland; ERC (European Research Council) “KaonLepton” starting grant 336581, Europe. Individuals have received support from: the Bulgarian National Science Fund under contract DID02-22; the Royal Society (grants UF100308, UF0758946), United Kingdom; ERC Starting Grant 336581, Europe.",

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AB - The NA48/2 experiment at CERN reports the first observation of the K± → π0π0μ±ν decay based on a sample of 2437 candidates with 15% background contamination collected in 2003–2004. The decay branching ratio in the kinematic region of the squared dilepton mass above 0.03 GeV2/c4 is measured to be (0.65 ± 0.03) × 10−6. The extrapolation to the full kinematic space, using a specific model, is found to be (3.45 ± 0.16) × 10−6, in agreement with chiral perturbation theory predictions.

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