New measurement of $K^+\toπ^+ν\barν$ branching ratio at the NA62 experiment

Fuente: arXiv
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Main Authors: Chang, Xiafei, Collaboration, for the NA62
Format: Preprint
Published: 2026
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author Chang, Xiafei
Collaboration, for the NA62
author_facet Chang, Xiafei
Collaboration, for the NA62
contents The ultra-rare decay $K^+\toπ^+ν\barν$ is a golden mode in flavor physics. The Standard Model prediction for its branching ratio is below $10^{-10}$. This decay mode is highly sensitive to new physics models at mass scales up to $\mathcal{O}(100\,\mathrm{TeV})$. The NA62 experiment at CERN SPS is designed to measure this decay mode. A preliminary result of the branching ratio measurement using data collected in 2023--2024 is presented. With the new dataset, the NA62 experiment doubled its signal sample while reducing the background in proportion. Combining the data collected in 2016--2024, the branching ratio is measured to be $\mathcal{B}(K^+\toπ^+ν\barν) = \left(9.6^{+1.9}_{-1.8}\right)\times10^{-11}$. The result is compatible with the Standard Model prediction with a precision better than $20\%$.
format Preprint
id arxiv_https___arxiv_org_abs_2604_12649
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle New measurement of $K^+\toπ^+ν\barν$ branching ratio at the NA62 experiment
Chang, Xiafei
Collaboration, for the NA62
High Energy Physics - Experiment
The ultra-rare decay $K^+\toπ^+ν\barν$ is a golden mode in flavor physics. The Standard Model prediction for its branching ratio is below $10^{-10}$. This decay mode is highly sensitive to new physics models at mass scales up to $\mathcal{O}(100\,\mathrm{TeV})$. The NA62 experiment at CERN SPS is designed to measure this decay mode. A preliminary result of the branching ratio measurement using data collected in 2023--2024 is presented. With the new dataset, the NA62 experiment doubled its signal sample while reducing the background in proportion. Combining the data collected in 2016--2024, the branching ratio is measured to be $\mathcal{B}(K^+\toπ^+ν\barν) = \left(9.6^{+1.9}_{-1.8}\right)\times10^{-11}$. The result is compatible with the Standard Model prediction with a precision better than $20\%$.
title New measurement of $K^+\toπ^+ν\barν$ branching ratio at the NA62 experiment
topic High Energy Physics - Experiment
url https://arxiv.org/abs/2604.12649