Научная группа: NA62 Collaboration
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First search for K+ -> pi(+) nu(nu)over-bar using the decay-in-flight technique
(2019) Gil, E. Cortina; Minucci, E.; Padolski, S.; Petrov, P.; Kudenko, Y.; Shaikhiev, A.; Куденко, Юрий Григорьевич
The NA62 experiment at the CERN SPS reports the first search for K+ -> pi(+) nu(nu) over bar using the decay-in-flight technique, based on a sample of 1.21 x10(11) K+ decays collected in 2016. The single event sensitivity is 3.15 x10(-10), corresponding to 0.267 Standard Model events. One signal candidate is observed while the expected background is 0.152 events. This leads to an upper limit of 14 x10(-10) on the K+ -> pi(+) nu(nu) over bar branching ratio at 95% CL. (c) 2019 The Author. Published by Elsevier B.V.
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Search for production of an invisible dark photon in (0) decays
(2019) Gil, E. Cortina.; Kleimenova, A.; Minucci, E.; Padolski, S.; Kudenko, Y.; Куденко, Юрий Григорьевич
The results of a search for (0) decays to a photon and an invisible massive dark photon at the NA62 experiment at the CERN SPS are reported. From a total of 4.12 x 10(8) tagged (0) mesons, no signal is observed. Assuming a kinetic-mixing interaction, limits are set on the dark photon coupling to the ordinary photon as a function of the dark photon mass, improving on previous searches in the mass range 60-110 MeV/c(2). The present results are interpreted in terms of an upper limit of the branching ratio of the electro-weak decay 0improving the current limit by more than three orders of magnitude.
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Searches for lepton number violating K+ decays
(2019) Gil, E. C.; Kleimenova, A.; Minucci, E.; Padolski, S.; Kudenko, Y.; Куденко, Юрий Григорьевич
The NA62 experiment at CERN reports a search for the lepton number violating decays K+ -> pi(-)e(+)e(+) and K+ -> pi(-)mu(+)mu(+) using a data sample collected in 2017. No signals are observed, and upper limits on the branching fractions of these decays of 2.2 x 10(-10) and 4.2 x 10(-11) are obtained, respectively, at 90% confidence level. These upper limits improve on previously reported measurements by factors of 3 and 2, respectively. (C) 2019 The Author. Published by Elsevier B.V.
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Search for heavy neutral lepton production in K+ decays to positrons
(2020) Gil, E. C.; Kleimenova, A.; Minucci, E.; Padolski, S.; Kudenko, Y.; Куденко, Юрий Григорьевич
A search for heavy neutral lepton (N) production in K+ -> e(+)N decays using the data sample collected by the NA62 experiment at CERN in 2017-2018 is reported. Upper limits of the extended neutrino mixing matrix element vertical bar U-e4 vertical bar(2) are established at the level of 10(-9) over most of the accessible heavy neutral lepton mass range 144-462 MeV/c(2), with the assumption that the lifetime exceeds 50 ns. These limits improve significantly upon those of previous production and decay searches. The vertical bar U-e4 vertical bar(2) range favoured by Big Bang Nucleosynthesis is excluded up to a mass of about 340 MeV/c(2). (C) 2020 The Author(s). Published by Elsevier B.V.
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An investigation of the very rare K+→ π+νν¯ decay
(2020) Cortina, Gil, E.; Kleimenova, A.; Minucci, E.; Padolski, S.; Kudenko, Y.; Куденко, Юрий Григорьевич
© 2020, The Author(s).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 (0.48−0.48+0.72) × 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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Институт ядерной физики и технологий
Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.
Описание
Эксперимент NA62 - это эксперимент по физике элементарных частиц с фиксированной мишенью в Северной зоне ускорителя SPS в ЦЕРНЕ. Эксперимент был одобрен в феврале 2007 года. Сбор данных начался в 2015 году, и ожидается, что эксперимент станет первым в мире исследованием распадов заряженного каона с вероятностями до 10-12. Представителем эксперимента является Кристина Лаццерони. В сотрудничестве участвуют 333 человека из 30 учреждений и 13 стран по всему миру.