A measurement of the K+→π+νν¯ 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 BK+→π+νν¯=13.0−3.0+3.3×10−11 is reported. With 51 signal candidates observed and an expected background of 18−2+3 events, BK+→π+νν¯ becomes the smallest branching ratio measured with a signal significance above 5σ.
Observation of the K+→π+νν¯ decay and measurement of its branching ratio / Cortina Gil, E., Jerhot, J., Lurkin, N., Numao, T., Velghe, B., Wong, V.W.S., Bryman, D., Hives, Z., Husek, T., Kampf, K., Kolesar, M., Koval, M., De Martino, B., Perrin-Terrin, M., Petit, L., Dobrich, B., Lezki, S., Schubert, J., Akmete, A.T., Aliberti, R., et al.. - In: JOURNAL OF HIGH ENERGY PHYSICS. - ISSN 1029-8479. - 2025:2(2025), pp. 0-0. [10.1007/JHEP02(2025)191]
Observation of the K+→π+νν¯ decay and measurement of its branching ratio
Lo Chiatto P.;Bizzeti A.;
2025
Abstract
A measurement of the K+→π+νν¯ 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 BK+→π+νν¯=13.0−3.0+3.3×10−11 is reported. With 51 signal candidates observed and an expected background of 18−2+3 events, BK+→π+νν¯ becomes the smallest branching ratio measured with a signal significance above 5σ.| File | Dimensione | Formato | |
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