Observation of the K+→π+νν̅ decay and measurement of its branching ratio

NA62 Collaboration; Renato Fiorenza; F. Brizioli; J. Swallow; Helen F Heath; et  al

doi:10.1007/JHEP02(2025)191

Observation of the K⁺→π⁺νν̅ decay and measurement of its branching ratio

NA62 Collaboration
, Renato Fiorenza^*
, F. Brizioli^*
, J. Swallow^*
, Helen F Heath
, et al

^*Corresponding author for this work

School of Physics

Research output: Contribution to journal › Article (Academic Journal) › peer-review

28 Citations (Scopus)

Abstract

A measurement of the K⁺→π⁺νν̅ decay by the NA62 experiment at the CERN SPS is presented, using data collected in 2021 and 2022. This dataset was recorded, after modifications to the beamline and detectors, at a higher instantaneous beam intensity with respect to the 2016–2018 data taking. Combining NA62 data collected in 2016–2022, a measurement of B(K⁺→π⁺νν̅)=(13.0^+3.3_−3.0)×10⁻¹¹is reported. With 51 signal candidates observed and an expected background of 18⁺³₋₂events, B(K⁺→π⁺νν̅) becomes the smallest branching ratio measured with a signal significance above 5σ.

Original language	English
Article number	191
Number of pages	26
Journal	Journal of High Energy Physics
Volume	2025
Issue number	2
DOIs	https://doi.org/10.1007/JHEP02(2025)191
Publication status	Published - 27 Feb 2025

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abstract = "A measurement of the K+→π+νν̅ decay by the NA62 experiment at the CERN SPS is presented, using data collected in 2021 and 2022. This dataset was recorded, after modifications to the beamline and detectors, at a higher instantaneous beam intensity with respect to the 2016–2018 data taking. Combining NA62 data collected in 2016–2022, a measurement of B(K+→π+νν̅)=(13.0+3.3−3.0)×10−11 is reported. With 51 signal candidates observed and an expected background of 18+3−2 events, B(K+→π+νν̅) becomes the smallest branching ratio measured with a signal significance above 5σ.",

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AU - NA62 Collaboration

AU - Fiorenza, Renato

AU - Brizioli, F.

AU - Swallow, J.

AU - Heath, Helen F

AU - al, et

PY - 2025/2/27

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N2 - A measurement of the K+→π+νν̅ decay by the NA62 experiment at the CERN SPS is presented, using data collected in 2021 and 2022. This dataset was recorded, after modifications to the beamline and detectors, at a higher instantaneous beam intensity with respect to the 2016–2018 data taking. Combining NA62 data collected in 2016–2022, a measurement of B(K+→π+νν̅)=(13.0+3.3−3.0)×10−11 is reported. With 51 signal candidates observed and an expected background of 18+3−2 events, B(K+→π+νν̅) becomes the smallest branching ratio measured with a signal significance above 5σ.

AB - A measurement of the K+→π+νν̅ decay by the NA62 experiment at the CERN SPS is presented, using data collected in 2021 and 2022. This dataset was recorded, after modifications to the beamline and detectors, at a higher instantaneous beam intensity with respect to the 2016–2018 data taking. Combining NA62 data collected in 2016–2022, a measurement of B(K+→π+νν̅)=(13.0+3.3−3.0)×10−11 is reported. With 51 signal candidates observed and an expected background of 18+3−2 events, B(K+→π+νν̅) becomes the smallest branching ratio measured with a signal significance above 5σ.

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DO - 10.1007/JHEP02(2025)191

M3 - Article (Academic Journal)

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Observation of the K+→π+νν̅ decay and measurement of its branching ratio