Measurement of the very rare K+ ? $$ {\pi}^{+}\nu \overline{\nu} $$ decay

نویسندگان

چکیده

A bstract The NA62 experiment reports the branching ratio measurement $$ \mathrm{BR}\left({K}^{+}\to {\pi}^{+}\nu \overline{\nu}\right)=\left({10.6}_{-3.4}^{+4.0}\left|{}_{\mathrm{stat}}\right.\pm {0.9}_{\mathrm{syst}}\right)\times {10}^{-11} BR K + ? ? ? ¯ = 10.6 ? 3.4 4.0 stat ± 0.9 syst × 10 11 at 68% CL, based on observation of 20 signal candidates with an expected background 7.0 events from total data sample collected CERN SPS during 2016–2018. This provides evidence for very rare K + ? \overline{\nu} decay, observed a significance 3.4 ? . achieves single event sensitivity (0 839 ± 0 054) × 10 ? 11 , corresponding to 10.0 assuming Standard Model (8 4 1 0) is also used set limits BR( ? X ), where scalar or pseudo-scalar particle. Details are given analysis 2018 sample, which corresponds about 80% sample.

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ژورنال

عنوان ژورنال: Journal of High Energy Physics

سال: 2021

ISSN: ['1127-2236', '1126-6708', '1029-8479']

DOI: https://doi.org/10.1007/jhep06(2021)093