| Article | |
| Report number | arXiv:1912.11389 ; CERN-EP-2019-284 |
| Title | Improved limits on a hypothetical X(16.7) boson and a dark photon decaying into $e^+e^-$ pairs |
| Author(s) |
Banerjee, D. (CERN ; Illinois U., Urbana (main)) ; Bernhard, J. (CERN) ; Burtsev, V.E. (Dubna, JINR) ; Chumakov, A.G. (Tomsk Pedagogical Inst.) ; Cooke, D. (University Coll. London) ; Crivelli, P. (Zurich, ETH) ; Depero, E. (Zurich, ETH) ; Dermenev, A.V. (Moscow, INR) ; Donskov, S.V. (Kurchatov Inst., Moscow) ; Dusaev, R.R. (Tomsk Pedagogical Inst.) ; Enik, T. (Dubna, JINR) ; Charitonidis, N. (CERN) ; Feshchenko, A. (Dubna, JINR) ; Frolov, V.N. (Dubna, JINR) ; Gardikiotis, A. (Patras U.) ; Gerassimov, S.G. (Munich, Tech. U. ; Lebedev Inst.) ; Gninenko, S.N. (Moscow, INR) ; Hösgen, M. (Bonn U., HISKP) ; Jeckel, M. (CERN) ; Kachanov, V.A. (Kurchatov Inst., Moscow) ; Karneyeu, A.E. (Moscow, INR) ; Kekelidze, G. (Dubna, JINR) ; Ketzer, B. (Bonn U., HISKP) ; Kirpichnikov, D.V. (Moscow, INR) ; Kirsanov, M.M. (Moscow, INR) ; Kolosov, V.N. (Kurchatov Inst., Moscow) ; Konorov, I.V. (Munich, Tech. U. ; Lebedev Inst.) ; Kovalenko, S.G. (CCTVal, Valparaiso) ; Kramarenko, V.A. (Dubna, JINR ; SINP, Moscow) ; Kravchuk, L.V. (Moscow, INR) ; Krasnikov, N.V. (Dubna, JINR ; Moscow, INR) ; Kuleshov, S.V. (Andres Bello Natl. U.) ; Lyubovitskij, V.E. (Tomsk Pedagogical Inst. ; CCTVal, Valparaiso) ; Lysan, V. (Dubna, JINR) ; Matveev, V.A. (Dubna, JINR) ; Mikhailov, Yu V. (Kurchatov Inst., Moscow) ; Molina Bueno, L. (Zurich, ETH) ; Peshekhonov, D.V. (Dubna, JINR) ; Polyakov, V.A. (Kurchatov Inst., Moscow) ; Radics, B. (Zurich, ETH) ; Rojas, R. (CCTVal, Valparaiso) ; Rubbia, A. (Zurich, ETH) ; Samoylenko, V.D. (Kurchatov Inst., Moscow) ; Shchukin, D. (Lebedev Inst.) ; Tikhomirov, V.O. (Lebedev Inst.) ; Tlisova, I. (Moscow, INR) ; Tlisov, D.A. (Moscow, INR) ; Toropin, A.N. (Moscow, INR) ; Trifonov, A. Yu (Moscow, INR ; Tomsk Pedagogical Inst.) ; Vasilishin, B.I. (Tomsk Pedagogical Inst.) ; Vasquez Arenas, G. (CCTVal, Valparaiso) ; Volkov, P.V. (Dubna, JINR ; SINP, Moscow) ; Volkov, V.Yu. (SINP, Moscow) ; Ulloa, P. (SINP, Moscow ; CCTVal, Valparaiso) |
| Publication | 2020-04-17 |
| Imprint | 2019-12-22 |
| Number of pages | 7 |
| Note | 7 pages, 5 figures, 1 table. arXiv admin note: substantial text overlap with arXiv:1803.07748 |
| In: | Phys. Rev. D 101 (2020) 071101 |
| DOI | 10.1103/PhysRevD.101.071101 |
| Subject category | hep-ex ; Particle Physics - Experiment |
| Accelerator/Facility, Experiment | CERN SPS ; NA64 |
| Abstract | 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. No evidence for such decays was found from the combined analysis of the data samples with total statistics corresponding to $8.4 \times 10^{10}$ electrons on target collected in 2017 and 2018. This allows to set the new limits on the $X-e^-$ coupling in the range $1.2 \times 10^{-4}\underset{\sim}{<}\epsilon_e \underset{\sim}{<}6.8\times 10^{-4}$, excluding part of the parameter space favored by the Berillium anomaly. We also set new bounds on the mixing strength of photons with dark photons ($A'$) from non-observation of the decay $A' \to e^+e^-$ of the bremsstrahlung $A'$ with a mass below 24 MeV. |
| Copyright/License | preprint: (License: arXiv nonexclusive-distrib 1.0) publication: © 2020-2024 authors (License: CC-BY-4.0) |
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