# NA62 Papers

Ostatnio dodane:
2022-08-20
22:53
 A search for the $K^+ \to \mu^- \nu e^+ e^+$ decay / Cortina Gil, E. A search for the $K^+ \to \mu^- \nu e^+ e^+$ decay forbidden within the Standard Model by either lepton number or lepton flavour conservation depending on the flavour of the emitted neutrino, has been performed using the dataset collected by the NA62 experiment at CERN in 2016–2018. An upper limit of $8.1 \times 10^{-11}$ is obtained for the decay branching fraction at 90% CL, improving by a factor of 250 over the previous search.. CERN-EP-2022-243.- Geneva : CERN, 2022 - 12. Draft (restricted): PDF; Fulltext: PDF;

2022-07-24
16:18
 A measurement of the $K^+ \to \pi^+ \mu^+ \mu^-$ decay / Cortina Gil, E. /NA62 Collaboration A sample of $2.8 \times 10^4$ $K^+ \to \pi^+ \mu^+ \mu^-$ candidates with negligible background was collected by the NA62 experiment at the CERN SPS in 2017-2018. The model-independent branching fraction is measured to be $(9.15 \pm 0.08) \times 10^{-8}$, a factor three more precise than previous measurements. [...] CERN-EP-2022-189; arXiv:2209.05076.- Geneva : CERN, 2022 - 13 p. Draft (restricted): PDF; Fulltext: CERN-EP-2022-189 - PDF; 2209.05076 - PDF;

2022-03-20
18:55
 Performance of the NA62 trigger system / Romano, A. (CERN) ; Parkinson, C. (CERN) The NA62 experiment at CERN targets the measurement of the ultra-rare $K^+ \to \pi^+ \nu \bar\nu$ decay, and carries out a broad physics programme that includes probes for symmetry violations and searches for exotic particles. Data were collected in 2016–2018 using a multi-level trigger system, which is described highlighting performance studies based on 2018 data.. arXiv:2208.00897; CERN-EP-2022-165.- Geneva : CERN, 2022 - 18 p. Draft (restricted): PDF; Fulltext: CERN-EP-2022-165 - PDF; 2208.00897 - PDF;

2021-12-07
15:18
 Searches for lepton number violating $K^+\to\pi^-(\pi^0)e^+e^+$ decays / NA62 Collaboration Searches for lepton number violating $K^+\to\pi^-e^+e^+$ and $K^+\to\pi^-\pi^0e^+e^+$ decays have been performed using the complete dataset collected by the NA62 experiment at CERN in 2016-2018. Upper limits of $5.3\times 10^{-11}$ and $8.5\times 10^{-10}$ are obtained on the decay branching fractions at 90% confidence level. [...] arXiv:2202.00331; CERN-EP-2022-018.- 2022-07-10 - 16 p. Draft (restricted): PDF; Fulltext: 2202.00331 - PDF; CERN-EP-2022-018 - PDF;

2021-02-16
21:16
 Measurement of the very rare $K^+\rightarrow\pi^+\nu\bar{\nu}$ decay / Cortina Gil, E The NA62 experiment reports the branching ratio measurement BR$(K^+ \rightarrow \pi^+ \nu\bar{\nu}) = (10.6^{+4.0}_{-3.4} |_{\rm stat} \pm 0.9_{\rm syst}) \times 10 ^{-11}$ at 68% CL, based on the observation of 20 signal candidates with an expected background of 7.0 events from the total data sample collected at the CERN SPS during 2016-2018. This provides evidence for the very rare $K^+ \to \pi^+ \nu\bar{\nu}$ decay, observed with a significance of 3.4$\sigma$. [...] CERN-EP-2021-050.- Geneva : CERN, 2021 - 22. Draft (restricted): PDF; Fulltext: PDF;

2020-12-28
00:04
 Search for lepton number and flavour violation in $K^+$ and $\pi^0$ decays / NA62 Collaboration Searches for the lepton number violating $K^+ \to \pi^− \mu^+ e^+$ decay and the lepton flavour violating $K^+ \to \pi^+ \mu^- e^+$ and $\pi^0 \to \mu^- e^+$ decays are reported using data collected by the NA62 experiment at CERN in 2017$-$2018. No evidence for these decays is found and upper limits of the branching ratios are obtained at 90% confidence level: B($K^+ \to \pi^− \mu^+ e^+$) $< 4.2 \times 10^{−11}$, B($K^+ \to \pi^+ \mu^- e^+$) $< 6.6 \times 10^{−11}$ and B($\pi^0 \to \mu^- e^+$) $< 3.2 \times 10^{−10}$. [...] arXiv:2105.06759; CERN-EP-2021-090.- Geneva : CERN, 2021-09-24 - 8 p. - Published in : Phys. Rev. Lett. 127 (2021) 131802 Draft (restricted): PDF; Fulltext: 2105.06759 - PDF; CERN-EP-2021-090 - PDF; Fulltext from publisher: PDF;

2020-12-11
19:52
 Search for $K^+$ decays to a muon and invisible particles / NA62 Collaboration The NA62 experiment at CERN reports searches for $K^+\to\mu^+N$ and $K^+\to\mu^+\nu X$ decays, where $N$ and $X$ are massive invisible particles, using the 2016-2018 data set. The $N$ particle is assumed to be a heavy neutral lepton, and the results are expressed as upper limits of ${\cal O}(10^{-8})$ of the neutrino mixing parameter $|U_{\mu4}|^2$ for $N$ masses in the range 200-384 MeV/$c^2$ and lifetime exceeding 50 ns. [...] arXiv:2101.12304; CERN-EP-2021-018.- Geneva : CERN, 2021-05-10 - 10 p. - Published in : Phys. Lett. B 816 (2021) 136259 Article from SCOAP3: PDF; Draft (restricted): PDF; Fulltext: 2101.12304 - PDF; CERN-EP-2021-018 - PDF;

2020-08-17
23:12
 Search for a feebly interacting particle $X$ in the decay $K^+ \to \pi^+ X$ / NA62 Collaboration A search for the $K^+ \to \pi^+ X$ decay, where $X$ is a long-lived feebly interacting particle, is performed through an interpretation of the $K^+ \to \pi^+ \nu \bar\nu$ analysis of data collected in 2017 by the NA62 experiment at CERN. Two ranges of $X$ masses, $0-110$ MeV/$c^2$ and $154-260$ MeV/$c^2$, and lifetimes above 100 ps are considered. [...] arXiv:2011.11329; CERN-EP-2020-227.- Geneva : CERN, 2021-03-04 - 14 p. - Published in : JHEP 2103 (2021) 058 Article from SCOAP3: scoap3-fulltext - PDF; scoap - PDF; Draft (restricted): PDF; Fulltext: 2011.11329 - PDF; CERN-EP-2020-227 - PDF;

2020-07-04
12:28
 Search for $\pi^0$ decays to invisible particles / NA62 Collaboration The NA62 experiment at the CERN SPS reports a study of a sample of $4 \times 10^9$ tagged $\pi^0$ mesons from $K^+ \to \pi^+ \pi^0 (\gamma)$, searching for the decay of the $\pi^0$ to invisible particles. No signal is observed in excess of the expected background fluctuations. [...] arXiv:2010.07644; CERN-EP-2020-193.- Geneva : CERN, 2021 - 27 p. - Published in : JHEP 02 (2021) 201 Article from SCOAP3: scoap3-fulltext - PDF; scoap - PDF; Draft (restricted): PDF; Fulltext: CERN-EP-2020-193 - PDF; 2010.07644 - PDF;

2020-05-09
19:08
 An investigation of the very rare $K^+\rightarrow\pi^+\nu\bar{\nu}$ decay / NA62 Collaboration The NA62 experiment reports an investigation of the $K^+\rightarrow\pi^+\nu\bar{\nu}$ mode from a sample of $K^+$ decays collected in 2017 at the CERN SPS. The experiment has achieved a single event sensitivity of $(0.389\pm 0.024)\times10^{-10}$, corresponding to 2.2 events assuming the Standard Model branching ratio of $(8.4\pm1.0)\times10^{-11}$. [...] arXiv:2007.08218; CERN-EP-2020-132.- Geneva : CERN, 2020-11-10 - 52 p. - Published in : JHEP 2011 (2020) 042 Article from SCOAP3: PDF; Draft (restricted): PDF; Fulltext: 2007.08218 - PDF; CERN-EP-2020-132 - PDF;