2023-09-05
13:59 |
Measurement of the $K^+ \to \pi^+ \gamma \gamma$ decay
/ Cortina Gil, Eduardo (Louvain U., CP3) ; Minucci, Elisa (Louvain U., CP3 ; Syracuse U.) ; Padolski, Sergey (Louvain U., CP3) ; Petrov, Plamen (Louvain U., CP3) ; Velghe, Bob (TRIUMF) ; Bryman, Douglas (British Columbia U. ; TRIUMF) ; Fu, Ji (British Columbia U.) ; Numao, Toshio (TRIUMF) ; Petrov, Yevgeniy (TRIUMF) ; Wong, Vincent Wai Sum (TRIUMF) et al.
A sample of 3984 candidates of the $K^+ \to \pi^+ \gamma \gamma$ decay, with an estimated background of $291 \pm 14$ events, was collected by the NA62 experiment at CERN during 2017–2018. In order to describe the observed di-photon mass spectrum, the next-to-leading order contribution in chiral perturbation theory was found to be necessary. [...]
arXiv:2311.01837; CERN-EP-2023-247.-
Geneva : CERN, 2023 - 20 p.
Draft (restricted): PDF; Fulltext: 2311.01837 - PDF; CERN-EP-2023-247 - PDF;
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2023-05-01
15:22 |
Search for $K^+$ decays into the $\pi^+e^+e^-e^+e^-$ final state
/ NA62 Collaboration
The first search for ultra-rare $K^+$ decays into the $\pi^+e^+e^-e^+e^-$ final state is reported, using a dataset collected by the NA62 experiment at CERN in 2017-2018. An upper limit of $1.4\times 10^{-8}$ at 90% CL is obtained for the branching ratio of the $K^+\to\pi^+e^+e^-e^+e^-$ decay, predicted in the Standard Model to be $(7.2 \pm0 .7)\times 10^{-11}$. [...]
arXiv:2307.04579; CERN-EP-2023-133.-
Geneva : CERN, 2023-09-22 - 9 p.
- Published in : Phys. Lett. B 846 (2023) 138193
Draft (restricted): PDF; Fulltext: CERN-EP-2023-133 - PDF; Publication - PDF; 2307.04579 - PDF;
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2023-02-15
14:50 |
A study of the $K^+ \to \pi^0 e^+ \nu \gamma$ decay
/ NA62 Collaboration
A sample of $1.3 \times 10^5 K^+ \to \pi^0 e^+ \nu \gamma$ candidates with less than 1% background was collected by the NA62 experiment at the CERN SPS in 2017-2018. Branching fraction measurements are obtained at percent relative precision in three restricted kinematic regions, improving on existing results by a factor larger than two. [...]
arXiv:2304.12271; CERN-EP-2023-069.-
Geneva : CERN, 2023-09-07 - 16 p.
- Published in : JHEP 2309 (2023) 040
Draft (restricted): PDF; Fulltext: CERN-EP-2023-069 - PDF; 2304.12271 - PDF; document - PDF;
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2022-12-02
13:01 |
Search for dark photon decays to $\mu^+ \mu^-$ at NA62
/ NA62 Collaboration
The NA62 experiment at CERN, designed to study the ultra-rare decay $K^+ \rightarrow \pi^+ \nu \bar\nu$, has also collected data in beam-dump mode. In this configuration, dark photons may be produced by protons dumped on an absorber and reach a decay volume beginning 80 m downstream. [...]
arXiv:2303.08666; CERN-EP-2023-032.-
Geneva : CERN, 2023-09-06 - 23 p.
- Published in : JHEP 2309 (2023) 035
Draft (restricted): PDF; Fulltext: CERN-EP-2023-032 - PDF; document - PDF; 2303.08666 - PDF;
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2022-08-20
22:53 |
A search for the $K^+ \to \mu^- \nu e^+ e^+$ decay
/ NA62 Collaboration
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..
arXiv:2211.04818; CERN-EP-2022-243.-
Geneva : CERN, 2023-03-10 - 12 p.
- Published in : Phys. Lett. B 838 (2023) 137679
Draft (restricted): PDF; Fulltext: 2211.04818 - PDF; Publication - PDF; CERN-EP-2022-243 - PDF;
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2022-08-01
22:23 |
Improved calorimetric particle identification in NA62 using machine learning techniques
/ Cortina Gil, Eduardo (Louvain U., CP3) ; Minucci, Elisa (Louvain U., CP3 ; Syracuse U.) ; Padolski, Sergey (Louvain U., CP3 ; Brookhaven) ; Petrov, Plamen (Louvain U., CP3) ; Velghe, Bob (TRIUMF) ; Bryman, Douglas (British Columbia U. ; TRIUMF) ; Fu, Ji (British Columbia U.) ; Numao, Toshio (TRIUMF) ; Petrov, Yevgeniy (TRIUMF) ; Wong, Vincent Wai Sum (TRIUMF) et al.
Measurement of the ultra-rare $K^+\to\pi^+\nu\bar\nu$ decay at the NA62 experiment at CERN requires high-performance particle identification to distinguish muons from pions. Calorimetric identification currently in use, based on a boosted decision tree algorithm, achieves a muon misidentification probability of $1.2\times 10^{-5}$ for a pion identification efficiency of 75% in the momentum range of 15$-$40 GeV/$c$. [...]
arXiv:2304.10580; CERN-EP-2023-066.-
Geneva : CERN, 2023 - 13 p.
Draft (restricted): PDF; Fulltext: 2304.10580 - PDF; CERN-EP-2023-066 - PDF;
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2022-07-24
16:18 |
A measurement of the $K^+ \to \pi^+ \mu^+ \mu^-$ decay
/ 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. [...]
arXiv:2209.05076; CERN-EP-2022-189.-
Geneva : CERN, 2022-11-04 - 19 p.
Draft (restricted): PDF; Fulltext: CERN-EP-2022-189 - PDF; document - PDF; 2209.05076 - PDF; Publication - PDF;
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2022-03-20
18:55 |
Performance of the NA62 trigger system
/ NA62 Collaboration
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, 2023-03-17 - 20 p.
- Published in : JHEP 2303 (2023) 122
Draft (restricted): PDF; Fulltext: CERN-EP-2022-165 - PDF; document - PDF; 2208.00897 - PDF;
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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;
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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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