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NA64 Papers

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2020-10-17
04:07
Hunting down the X17 boson at the CERN SPS / NA64 Collaboration
Recently, the ATOMKI experiment has reported new evidence for the excess of $e^+ e^-$ events with a mass $\sim$17 MeV in the nuclear transitions of $^4$He, that they previously observed in measurements with $^8$Be. [...]
arXiv:2009.02756.
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Fulltext

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2020-10-17
04:07
Photoproduction of axionlike particles in the NA64 experiment / Dusaev, R.R. (Tomsk State U.) ; Kirpichnikov, D.V. (Moscow, INR) ; Kirsanov, M.M. (Moscow, INR)
Axion-like particles $a$ (ALPs) that couple to the Standard Model (SM) gauge fields could be observed in the high-energy photon scattering $\gamma N\to N a$ off nuclei followed by the $a\to \gamma\gamma$ decay. In the present paper we describe the calculation of the ALP production cross-section and the properties of this production. [...]
arXiv:2004.04469.- 2020-09-29 - 8 p. - Published in : Phys. Rev. D 102 (2020) 055018 Article from SCOAP3: PDF; Fulltext: PDF;

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2020-08-04
06:57
Status and Plans for the NA64 Experiment / Bernhard, J (CERN) /NA64 Collaboration ; Physics Beyond Collider Conventional Beams working group Collaboration
The NA64 experiment at the CERN North Area searches for dark matter production via both visible and invisible decays of sub-GeV vector mediators, such as the dark photon $A$´. In a first data taking period from 2016-2018, $A$' generation from the reaction e Z $\rightarrow$ e Z $A$' and subsequent decays $A$´ $\rightarrow x\overline{x}$ and $A$´ $\rightarrow$ e$^+$e$^-$ was studied with the help of an active dump set-up using 100 GeV/$c$ and 150 GeV/$c$ electrons. [...]
IOP, 2020 - 4 p. - Published in : J. Phys. : Conf. Ser. 1468 (2020) 012023 Published fulltext: PDF;
In : 16th International Conference on Topics in Astroparticle and Underground Physics, Toyama, Japan, 9 - 13 Sep 2019, pp.012023

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2020-04-29
13:43
Search for Axionlike and Scalar Particles with the NA64 Experiment / NA64 Collaboration
We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced through the Primakoff effect in interactions of hard bremsstrahlung photons generated by 100 GeV electrons in the NA64 active dump with virtual photons provided by the nuclei of the dump. [...]
arXiv:2005.02710; CERN-EP-2020-068.- 2020-08-17 - 7 p. - Published in : Phys. Rev. Lett. 125 (2020) 8 Article from SCOAP3: PDF; Draft (restricted): PDF; Fulltext: 2005.02710 - PDF; CERN-EP-2020-068 - PDF;

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2020-03-12
06:25
Straw Chambers for the NA64 Experiment / Volkov, V Yu (SINP, Moscow) ; Volkov, P V (Dubna, JINR) ; Enik, T L (Dubna, JINR) ; Kekelidze, G D (Dubna, JINR) ; Kramarenko, V A (Dubna, JINR) ; Lysan, V M (Dubna, JINR) ; Peshekhonov, D V (Dubna, JINR) ; Solin, A A (Minsk, Inst. Nucl. Problems) ; Solin, A V (Minsk, Inst. Nucl. Problems)
The aim of this work is to describe the characteristics and properties of the particle-tracking detectors created at the Joint Institute for Nuclear Research by the glued straw tube technology for the NA64 experiment on the extracted electron beam of the CERN SPS. The physical task of the experiment is to search for phenomena of the dark sector and dark matter..
2019 - 12 p. - Published in : Phys. Part. Nucl. Lett. 16 (2019) 847-858

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2020-03-12
04:44
The exact tree-level calculation of the dark photon production in high-energy electron scattering at the CERN SPS / Gninenko, S.N. (Moscow, INR) ; Kirpichnikov, D.V. (Moscow, INR) ; Kirsanov, M.M. (Moscow, INR) ; Krasnikov, N.V. (Dubna, JINR ; Moscow, INR)
Dark photon ($A'$) that couples to the standard model fermions via the kinetic mixing with photons and serves as a mediator of dark matter production could be observed in the high-energy electron scattering $e^- + Z ~\rightarrow e^- + Z + A'$ off nuclei followed by the $A' \to invisible $ decay. We have performed the exact, tree-level calculations of the $A'$ production cross sections and implemented them in the program for the full simulation of such events in the experiment NA64 at the CERN SPS. [...]
arXiv:1712.05706.- 2018-07-10 - 6 p. - Published in : Phys. Lett. B 782 (2018) 406-411 Article from SCOAP3: PDF; Preprint: PDF;

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2020-03-12
04:44
Prospects of models with light sgoldstino in electron beam dump experiment at CERN SPS / Astapov, K.O. (Moscow, INR ; Moscow State U.) ; Kirpichnikov, D.V. (Moscow, INR)
We discuss phenomenology of light scalar sgoldstino in context of CERN electron beam dump experiment NA64. [...]
INR-TH-2016-048 ; arXiv:1612.02813.
- 5 p.
Preprint

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2019-12-26
04:22
Improved limits on a hypothetical X(16.7) boson and a dark photon decaying into $e^+e^-$ pairs / NA64 Collaboration
The improved results on a direct search for a new $X$(16.7 MeV) boson which could explain the anomalous excess of $e^+e^-$ pairs observed in the excited $^8Be^*$ nucleus decays ("Berillium anomaly") are reported. Due to its coupling to electrons, the $X$ boson could be produced in the bremsstrahlung reaction $e^-Z\rightarrow e^-ZX$ by a high-energy beam of electrons incident on active target in the NA64 experiment at the CERN SPS and observed through its subsequent decay into $e^+e^-$ pair. [...]
arXiv:1912.11389; CERN-EP-2019-284.- 2020-04-17 - 7 p. - Published in : Phys. Rev. D 101 (2020) 071101 Article from SCOAP3: PDF; Fulltext: PDF;

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2019-11-21
04:03
Studies for New Experiments at the CERN M2 Beamline within "Physics Beyond Colliders": AMBER/COMPASS++, NA64$\mu$, MuonE / Bernhard, Johannes (CERN) ; Banerjee, Dipanwita (Illinois U., Urbana (main) ; CERN) ; Montbarbon, Eva (CERN) ; Brugger, Markus (CERN) ; Charitonidis, Nikolaos (CERN) ; Cholak, Serhii (CERN) ; D'Alessandro, Gian Luigi (Royal Holloway, U. of London ; CERN) ; Gatignon, Lau (CERN) ; Gerbershagen, Alexander (CERN) ; Rae, Bastien (CERN) et al.
The "Physics Beyond Colliders (PBC)" study explores fundamental physics opportunities at the CERN accelerator complex complementary to collider experiments. Three new collaborations aim to exploit the M2 beamline in the North Area with existing high-intensity muon and hadron beams, but also aspire to go beyond the current M2 capabilities with a RF-separated, high intensity hadron beam, under study. [...]
arXiv:1911.01498.- 2020-07-27 - 7 p. - Published in : AIP Conf. Proc. 2249 (2020) 030035 Fulltext: PDF;
In : The 15th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon, MENU-2019, Pittsburgh, Pennsylvania, United States Of America, 2 - 7 Jun 2019, pp.030035

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2019-11-15
06:29
Recent results of the NA64 experiment at the CERN SPS / Kirsanov, Mikhail (Moscow, INR)
We report on the results of the search 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’ . [...]
2019 - 8 p. - Published in : EPJ Web Conf. 212 (2019) 06005 Fulltext: PDF;
In : 12th International Workshop on e+e- collisions from Phi to Psi, Novosibirsk, Russian Federation, 25 Feb - 01 Mar 2019, pp.06005

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