An investigation of the very rare {K}^{+}\to {\pi}^{+}\nu \overline{\nu}K + →π + ν ν decay
(2020) Journal of High Energy Physics (Print) — Vol. 11, n° 042, p. 42 (2020)
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- Abstract
- The NA62 experiment reports an investigation of the K+ → π+νν¯ mode from a sample of K+ decays collected in 2017 at the CERN SPS. The experiment has achieved a single event sensitivity of (0.389 ± 0.024) × 10−10, corresponding to 2.2 events assuming the Standard Model branching ratio of (8.4 ± 1.0) × 10−11. Two signal candidates are observed with an expected background of 1.5 events. Combined with the result of a similar analysis conducted by NA62 on a smaller data set recorded in 2016, the collaboration now reports an upper limit of 1.78×10−10 for the K+ → π+νν¯ branching ratio at 90% CL. This, together with the corresponding 68% CL measurement of (0.48+0.72 −0.48)×10−10, are currently the most precise results worldwide, and are able to constrain some New Physics models that predict large enhancements still allowed by previous measurements.
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Cortina Gil, E., Kleimenova, A., & Lurkin, N. (2020). An investigation of the very rare {K}^{+}\to {\pi}^{+}\nu \overline{\nu}K + →π + ν ν decay. Journal of High Energy Physics (Print), 11(042), 42. https://doi.org/10.1007/JHEP11(2020)042 (Original work published 2020)