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NA64 Papers

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2022-07-23
04:03
Search for a New $B$ - $L$ $Z'$ Gauge Boson with the NA64 Experiment at CERN / NA64 Collaboration
A search for a new $Z'$ gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22e11 electrons on target collected during 2016-2021 runs no signal events were found. [...]
arXiv:2207.09979; CERN-EP-2022-156.- 2022-10-12 - 7 p. - Published in : Phys. Rev. Lett. 129 (2022) 161801 Fulltext: PDF;

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2022-07-08
04:18
Leptonic scalar portal: Origin of muon g-2 anomaly and dark matter? / Gninenko, S.N. (Moscow, INR) ; Krasnikov, N.V. (Moscow, INR ; Dubna, JINR) /NA64 Collaboration
We present a model explaining both the 4.2 $\sigma$ muon $g-2$ anomaly and the relic density of dark matter (DM) in which DM interacts with the Standard Model (SM) via a scalar portal boson $\varphi$ carrying both dark and SM leptonic numbers, and mediating a nondiagonal interaction between the electron and muon that allows $e \leftrightarrow \mu$ transitions. The $\varphi$ could be produced in high-energy electron scattering off a target nuclei in the reaction $e Z \to \mu Z\varphi$ followed by the prompt invisible decay $\varphi~\to$~DM particles and searched for in events with large missing energy accompanied by a single outgoing muon in the final state. [...]
arXiv:2202.04410.- 2022-07-01 - 6 p. - Published in : Phys. Rev. D 106 (2022) 015003 Fulltext: PDF;

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2022-06-24
04:59
Search for a light $Z′$ in the $L_μ-L_τ$ scenario with the NA64-$e$ experiment at CERN / NA64 Collaboration
The extension of Standard Model made by inclusion of additional $U(1)$ gauge $L_\mu-L_\tau$ symmetry can explain the difference between the measured and the predicted value of the muon magnetic moment and solve the tension in $B$ meson decays. This model predicts the existence of a new, light $Z^\prime$ vector boson, predominantly coupled to second and third generation leptons, whose interaction with electrons is due to a loop mechanism involving muons and taus. [...]
arXiv:2206.03101.- 2022-08-01 - 11 p. - Published in : Phys. Rev. D 106 (2022) 032015 Fulltext: PhysRevD.106.032015 - PDF; 2206.03101 - PDF;

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2022-06-01
16:42
Search for a light muon-philic Z′ with the NA64-e experiment at CERN / Andreev, Yu. M. ; Banerjee, D. ; Banto Oberhauser, B. ; Bernhard, J. ; Bisio, P. ; Bondì, M. ; Burtsev, V. E. ; Celentano, A. ; Charitonidis, N. ; Chumakov, A. G. et al.
The extension of Standard Model made by inclusion of additional U (1) gauge L_μ − L_τ symmetry can explain the difference between the measured and the predicted value of the muon magnetic moment and solve the tension in B meson decays. This model predicts the existence of a new, light Z′ vector boson, predominantly coupled to second and third generation leptons, whose interaction with electrons is due to a loop mechanism involving muons and taus. [...]
CERN-EP-2022-118.- Geneva : CERN, 2022 Draft (restricted): PDF; Fulltext: CERN-EP-2022-118 - PDF; CERN-EP-2022-118_2 - PDF;

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2022-01-12
06:18
Search for light dark matter in the NA64 experiment / Gninenko, S N (Moscow, INR) ; Krasnikov, N V (Moscow, INR ; Dubna, JINR) ; Matveev, V A (Moscow, INR ; Dubna, JINR)
We review the most important models of light dark matter and discuss the NA64 experiment aimed at searching for hypothetical particles, including dark matter, in the mass range $\le \it {O}\rm{(1)}$ GeV with the use of electron and muon beams at the Super Proton Synchrotron (SPS) accelerator at CERN. We consider the methods and results of searches in the NA64 and other accelerator experiments and also discuss their further prospects..
2021 - 26 p. - Published in : Uspekhi Fiz. Nauk 191 (2021) 1361-1386 External link: Fulltext

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2021-08-12
10:11
$X_{17}$ anomaly and prospects for its verification with NA64 experiment / Molina Bueno, Laura (Zurich, ETH) /NA64 Collaboration
The ATOMKI collaboration reported a 7$\sigma$ excess in the angular distribution of $e^{+}e^{-}$ events in the nuclear de-excitation of $^8$Be, which was recently confirmed by new results on other nuclei, $^4$He. This anomaly could be explained by the existence of a new boson $X_{17}$ with a mass around 17 MeV and spin 0 or 1. [...]
SISSA, 2021 - 6 p. - Published in : PoS LHCP2020 (2021) 177 Fulltext: PDF;
In : 8th Conference of Large Hadron Collider Physics (LHCP), Online, 25 - 30 May 2020, pp.177

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2021-07-02
11:17
Probing the explanation of the muon (g-2) anomaly and thermal light dark matter with the semi-visible dark photon channel / Cazzaniga, C. (Zurich, ETH) ; Odagiu, P. (Zurich, ETH ; EPFL, Lausanne, FSL) ; Depero, E. (Zurich, ETH) ; Bueno, L. Molina (Zurich, ETH ; Valencia U., IFIC) ; Andreev, Yu. M. (Moscow, INR) ; Banerjee, D. (CERN ; Illinois U., Urbana (main)) ; Bernhard, J. (CERN) ; Burtsev, V.E. (Dubna, JINR) ; Charitonidis, N. (CERN) ; Chumakov, A.G. (Tomsk Pedagogical Inst. ; Tomsk Polytechnic U.) et al.
We report the results of a search for a new vector boson ($\gp$) decaying into two dark matter particles $\chi_1 \chi_2$ of different mass. The heavier $\chi_2$ particle subsequently decays to $\chi_1$ and $\gp \to \pair$. [...]
arXiv:2107.02021.- Geneva : CERN, 2021-10-30 - 6. - Published in : Eur. Phys. J. C 81 (2021) 959 Draft (restricted): PDF; Fulltext: 2107.02021 - PDF; document - PDF; CERN-EP-2021-129 - PDF;

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2021-04-30
04:20
Search for pseudoscalar bosons decaying into e+e- pairs in the NA64 experiment at the CERN SPS / NA64 Collaboration
We report the results of a search for a light pseudoscalar particle $a$ that couples to electrons and decays to $e^+e^-$ performed using the high-energy CERN SPS H4 electron beam. If such pseudoscalar with a mass $\simeq 17$ MeV exists, it could explain the ATOMKI anomaly. [...]
arXiv:2104.13342.- 2021-12-01 - 5 p. - Published in : Phys. Rev. D 104 (2021) L111102 Fulltext: 2104.13342 - PDF; PhysRevD.104.L111102 (1) - PDF; PhysRevD.104.L111102 - PDF;

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2021-04-26
18:01
Search for pseudoscalar bosons decaying into e+e- pairs / Banerjee, D ; Bernhard, J ; Burtsev, V ; Chumakov, A ; Cooke, D ; Crivelli, P ; Depero, E ; Dermenev, A ; Donskov, S ; Dusaev, R et al. /NA64
We report the results of a search for a light pseudoscalar particle $a$ that couples to electrons and decays to $e^+e^-$ performed using the high-energy CERN SPS H4 electron beam. If such pseudoscalar with a mass $\simeq 17$ MeV exists, it could explain the ATOMKI anomaly. [...]
CERN-EP-2021-069.- Geneva : CERN, 2021 - 6. Draft (restricted): PDF; Fulltext: PDF;

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2021-04-21
06:17
Search for Dark Sector Physics in Missing Energy Events in the NA64 Experiment / Kirsanov, Mikhail (Moscow, INR)
A search is performed for a new sub-GeV vector boson (A′) mediated production of Dark Matter (χ) in the fixed-target experiment, NA64, at the CERN SPS. The A′, called dark photon, could be generated in the reaction e−Z → e−ZA′ of 100 GeV electrons dumped against an active target which is followed by the prompt invisible decay A′→χχ¯. [...]
2019 - 17 p. - Published in : 10.1142/9789811202339_0066
In : 18th Lomonosov Conference on Elementary Particle Physics : Particle Physics at the Silver Jubilee of Lomonosov Conferences, Moscow, Russia, 24 - 30 Aug 2017, pp.353-369

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