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Accepted author manuscript
Licence: CC BY: Creative Commons Attribution 4.0 International License
Final published version
Licence: CC BY: Creative Commons Attribution 4.0 International License
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - An investigation of the very rare K+ to π+ νν- decay
AU - NA62 Collaboration
AU - Carmignani, Joe
AU - Jones, Roger William Lewis
AU - Ruggiero, Giuseppe
AU - Dainton, John
PY - 2020/11/10
Y1 - 2020/11/10
N2 - The NA62 experiment reports an investigation of the K+ to 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+ to 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.
AB - The NA62 experiment reports an investigation of the K+ to 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+ to 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.
U2 - 10.1007/JHEP11(2020)042
DO - 10.1007/JHEP11(2020)042
M3 - Journal article
VL - 2020
JO - Journal of High Energy Physics
JF - Journal of High Energy Physics
SN - 1029-8479
M1 - 42
ER -