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Article
Report number	arXiv:1803.07748 ; CERN-EP-2018-043
Title	Search for a new X(16.7) boson and dark photons in the NA64 experiment at CERN
Author(s)	Banerjee, D. (Illinois U., Urbana (main)) ; Burtsev, V.E. (Tomsk Pedagogical Inst.) ; Chumakov, A.G. (Tomsk Pedagogical Inst.) ; Cooke, D. (Zurich, ETH) ; Crivelli, P. (Zurich, ETH) ; Depero, E. (Zurich, ETH) ; Dermenev, A.V. (Moscow, INR) ; Donskov, S.V. (Serpukhov, IHEP) ; 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. (Lebedev Inst. ; Munich, Tech. U.) ; Gninenko, SN (Moscow, INR) ; Hösgen, M. (Bonn U., HISKP) ; Jeckel, M. (CERN) ; Karneyeu, A.E. (Moscow, INR) ; Kekelidze, G. (Dubna, JINR) ; Ketzer, B. (Bonn U., HISKP) ; Kirpichnikov, D.V. (Moscow, INR) ; Kirsanov, M.M. (Moscow, INR) ; Konorov, I.V. (Lebedev Inst. ; Munich, Tech. U.) ; Kovalenko, S.G. (CCTVal, Valparaiso) ; Kramarenko, V.A. (Dubna, JINR ; SINP, Moscow) ; Kravchuk, L.V. (Moscow, INR) ; Krasnikov, N.V. (Moscow, INR) ; Kuleshov, S.V. (CCTVal, Valparaiso) ; Lyubovitskij, V.E. (Tomsk Pedagogical Inst. ; CCTVal, Valparaiso) ; Lysan, V. (Dubna, JINR) ; Matveev, V.A. (Dubna, JINR) ; Mikhailov, Yu.V. (Serpukhov, IHEP) ; Peshekhonov, D.V. (Dubna, JINR) ; Polyakov, V.A. (Serpukhov, IHEP) ; Radics, B. (Zurich, ETH) ; Rojas, R. (CCTVal, Valparaiso) ; Rubbia, A. (Zurich, ETH) ; Samoylenko, V.D. (Serpukhov, IHEP) ; Tikhomirov, V.O. (Lebedev Inst.) ; Tlisov, D.A. (Moscow, INR) ; Toropin, A.N. (Moscow, INR) ; Trifonov, A.Yu. (Tomsk Pedagogical Inst.) ; Vasilishin, B.I. (Tomsk Pedagogical Inst.) ; Vasquez Arenas, G. (CCTVal, Valparaiso) ; Volkov, P.V. (Dubna, JINR ; SINP, Moscow) ; Volkov, V. (SINP, Moscow) ; Ulloa, P. (CCTVal, Valparaiso)
Publication	2018-06-09
Imprint	12 Mar 2018
Number of pages	6
Note	* Temporary entry * 6 pages, 3 figures. Title changed as suggested by Journal; references added; version published in Phys. Rev. Lett
Published in:	Phys. Rev. Lett. 120 (2018) 231802
DOI	10.1103/PhysRevLett.120.231802
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	not applicable ; not applicable CERN SPS ; NA64
Keywords	exotics ; rare decay ; experimental results ; Dark Matter ; Hidden Sector ; Dark Photon
Abstract	We report the first results on a direct search for a new 16.7 MeV boson (X) which could explain the anomalous excess of e+e- pairs observed in the excited 8Be* nucleus decays. Due to its coupling to electrons, the X could be produced in the bremsstrahlung reaction e-Z -> e-ZX by a 100 GeV e- beam incident on an active target in the NA64 experiment at the CERN SPS and observed through the subsequent decay into a e+e- pair. With 5.4x10^10 electrons on target no evidence for such decays was found, allowing to set first limits on the X-e- coupling in the range 1.3x10^-4 e+e- of the bremsstrahlung A' with a mass < 23 MeV.
Other source	Inspire
Copyright/License	Preprint: © 2018-2024 CERN (License: CC-BY-4.0)
Submitted by	[email protected]