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CERN Document Server 2,051 záznamov nájdených  1 - 10ďalšíkoniec  skoč na záznam: Hľadanie trvalo 2.58 sekúnd. 
1.
First search for $K^+ \to \pi^0 \pi \mu e$ decays / NA62 Collaboration
The first search for the lepton number violating decay $K^+ \to \pi^0 \pi^- \mu^+ e^+$ and lepton flavour violating decays $K^+ \to \pi^0 \pi^+ \mu^- e^+$, $K^+ \to \pi^0 \pi^+ \mu^+ e^-$ has been performed using a dataset collected by the NA62 experiment at CERN in 2016–2018. Upper limits of $2.9\times 10^{-10}$, $3.1 \times 10^{-10}$ and $5.0 \times 10^{-10}$, respectively, are obtained at 90% CL for the branching ratios of the three decays on the assumption of uniform phase-space distributions..
arXiv:2409.12981; CERN-EP-2024-224.- Geneva : CERN, 2024-11-12 - 9 p. - Published in : Phys. Lett. B 859 (2024) 139122 Draft (restricted): PDF; Fulltext: CERN-EP-2024-224 - PDF; 2409.12981 - PDF; Publication - PDF;
2.
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;
3.
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;
4.
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;
5.
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, 2020-07-02 - 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;
6.
Measurement of the $K^+ \to \pi^+ \gamma \gamma$ decay / NA62 Collaboration
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, 2024-02-07 - 11 p. - Published in : Phys. Lett. B 850 (2024) 138513 Draft (restricted): PDF; Fulltext: CERN-EP-2023-247 - PDF; 2311.01837 - PDF; Publication - PDF;
7.
First measurement of coherent $\rho^{0}$ photoproduction in ultra-peripheral Xe-Xe collisions at $\sqrt{s_{\rm NN}} = 5.44$ TeV / ALICE Collaboration
The first measurement of the coherent photoproduction of $\rho^{0}$ vector mesons in ultra-peripheral Xe-Xe collisions at $\sqrt{s_{\rm NN}} = 5.44$ TeV is presented. This result, together with previous $\gamma$p and $\gamma$-Pb measurements, describes the atomic number ($A$) dependence of this process, which is particularly sensitive to nuclear shadowing effects and to the approach to the black-disc limit of QCD at a semi-hardscale. [...]
arXiv:2101.02581; CERN-EP-2020-252.- Geneva : CERN, 2021-09-10 - 21 p. - Published in : Phys. Lett. B 820 (2021) 136481 Draft (restricted): PDF; Fulltext: PDF; Fulltext from publisher: PDF;
8.
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; Publication - PDF; Fulltext from publisher: PDF;
9.
A search for an unexpected asymmetry in the production of $e^+ \mu^-$ and $e^- \mu^+$ pairs in proton-proton collisions recorded by the ATLAS detector at $\sqrt s = 13$ TeV / ATLAS Collaboration
This search, a type not previously performed at ATLAS, uses a comparison of the production cross sections for $e^+ \mu^-$ and $e^- \mu^+$ pairs to constrain physics processes beyond the Standard Model. It uses $139 \text{fb}^{-1}$ of proton-proton collision data recorded at $\sqrt{s} = 13$ TeV at the LHC. [...]
arXiv:2112.08090; CERN-EP-2021-190.- Geneva : CERN, 2022-07-10 - 38 p. - Published in : Phys. Lett. B 830 (2022) 137106 Fulltext: 2112.08090 - PDF; Publication - PDF; External link: Previous draft version
10.
Nuclear modification factor of light neutral-meson spectra up to high transverse momentum in p-Pb collisions at $\mathbf{\sqrt{s_{NN}}}$ = 8.16 TeV / ALICE Collaboration
Neutral pion and $\eta$ meson production cross sections were measured up to unprecedentedly high transverse momenta ($p_{\rm T}$) in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 8.16 TeV. The mesons were reconstructed via their two-photon decay channel in the rapidity interval $-1.3< y <0.3$ in the ranges of $0.410$ GeV/$c$. [...]
arXiv:2104.03116; CERN-EP-2021-053.- Geneva : CERN, 2022-04-10 - 19 p. - Published in : Phys. Lett. B 827 (2022) 136943 Draft (restricted): PDF; Fulltext: 1-s2.0-S0370269322000776-main - PDF; 2104.03116 - PDF; Supplemental material: PDF;

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