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NA62 Papers

新增:
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;

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2020-12-28
00:04
Search for lepton number and flavour violation in $K^+ $ and $\pi^0$ decays / Cortina Gil, E
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($\pi^0 \to \mu^- e^+$) $< 3.2 \times 10^{−10}$. [...]
CERN-EP-2021-090.- Geneva : CERN, 2021 - 8. Draft (restricted): PDF; Fulltext: PDF;

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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;

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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: PDF; Draft (restricted): PDF; Fulltext: 2011.11329 - PDF; CERN-EP-2020-227 - PDF;

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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, 2019 - 27 p. - Published in : JHEP 05 (2019) 182 Article from SCOAP3: PDF; Draft (restricted): PDF; Fulltext: CERN-EP-2020-193 - PDF; 2010.07644 - PDF;

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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;

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2020-03-20
13:46
Search for heavy neutral lepton production in $K^+$ decays to positrons / NA62 Collaboration
A search for heavy neutral lepton ($N$) production in $K^+\to e^+N$ 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 $|U_{e4}|^2$ 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. [...]
arXiv:2005.09575; CERN-EP-2020-089.- Geneva : CERN, 2020-08-10 - 9 p. - Published in : Phys. Lett. B 807 (2020) 135599 Article from SCOAP3: PDF; Fulltext: 2005.09575 - PDF; CERN-EP-DRAFT-NA62-2020-001 - PDF; Fulltext from publisher: PDF;

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2019-03-25
15:48
Searches for lepton number violating $K^+$ decays / NA62 Collaboration
The NA62 experiment at CERN reports a search for the lepton number violating decays  $K^+ \to \pi^- e^+ e^+$ and $K^+ \to \pi^- \mu^+ \mu^+$ using a data sample collected in 2017. No signals are observed, and upper limits on the branching fractions of these decays of $2.2\times 10^{-10}$ and $4.2\times 10^{-11}$ are obtained, respectively, at 90\% confidence level. [...]
arXiv:1905.07770; CERN-EP-2019-104.- 2019-10-10 - 14 p. - Published in : Phys. Lett. B 797 (2019) 134794 Article from SCOAP3: PDF; Draft (restricted): PDF; Fulltext: 1905.07770 - PDF; CERN-EP-2019-104 - PDF;

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2019-02-02
15:59
Search for production of an invisible dark photon in $\pi^0$ decays / NA62 Collaboration
The results of a search for $\pi^0$ decays to a photon and an invisible massive dark photon at the NA62 experiment at the CERN SPS are reported. From a total of $4.12\times10^8$ tagged $\pi^0$ mesons, no signal is observed. [...]
arXiv:1903.08767; CERN-EP-2019-048.- Geneva : CERN, 2019-05-28 - 17. - Published in : JHEP 05 (2019) 182 Article from SCOAP3: PDF; Draft (restricted): PDF; Fulltext: CERN-EP-2019-048 - PDF; 1903.08767 - PDF;

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2018-09-14
17:44
First search for $K^+ \to \pi^+ \nu \bar\nu$ using the decay-in-flight technique / NA62 Collaboration
The NA62 experiment at the CERN SPS reports the first search for $K^+ \to \pi^+ \nu \bar{\nu}$ using the decay-in-flight technique, based on a sample of $1.21\times10^{11}$ $K^+$ decays collected in 2016. The single event sensitivity is $3.15 \times 10^{-10}$, corresponding to 0.267 Standard Model events. [...]
arXiv:1811.08508; CERN-EP-2018-314.- Geneva : CERN, 2019-04-10 - 11 p. - Published in : Phys. Lett. B 791 (2019) 156-166 Article from SCOAP3: PDF; Draft (restricted): PDF; Fulltext: 1811.08508 - PDF; CERN-EP-2018-314 - PDF;

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