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035			_a(RuTPU)RU\TPU\network\40178
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090			_a668941
100			_a20230203a2021 k y0engy50 ba
101	0		_aeng
102			_aUS
135			_adrcn ---uucaa
181		0	_ai
182		0	_ab
200	1		_aSearch for pseudoscalar bosons decaying into e+e− pairs in the NA64 experiment at the CERN SPS _fYu. M. Andreev, D. Banerjee, J. Bernhard [et al.]
203			_aText _celectronic
300			_aTitle screen
320			_a[References: 36 tit.]
330			_aWe 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 light pseudoscalar exists, it could explain the ATOMKI anomaly (an excess of e+e− pairs in the nuclear transitions of 8Be and 4He nuclei at the invariant mass ≃17  MeV observed by the experiment at the 5 MV Van de Graaff accelerator at ATOMKI, Hungary). We used the NA64 data collected in the “visible mode” configuration with a total statistics corresponding to 8.4×1010 electrons on target (EOT) in 2017 and 2018. In order to increase sensitivity to small coupling parameter ε we also used the data collected in 2016-2018 in the “invisible mode” configuration of NA64 with a total statistics corresponding to 2.84×1011 EOT. The background and efficiency estimates for these two configurations were retained from our previous analyses searching for light vector bosons and axionlike particles (ALP) (the latter were assumed to couple predominantly to γ). In this work we recalculate the signal yields, which are different due to different cross section and lifetime of a pseudoscalar particle a, and perform a new statistical analysis. As a result, the region of the two dimensional parameter space ma−ε in the mass range from 1 to 17.1 MeV is excluded. At the mass of the central value of the ATOMKI anomaly (the first result obtained on the beryllium nucleus, 16.7 MeV) the values of ε in the range 2.1×10−4<ε<3.2×10−4 are excluded.
461			_tPhysical Review D _ocovering particles, fields, gravitation, and cosmology
463			_tVol. 104, iss. 11 _v[L111102, 5 p.] _d2021
610	1		_aэлектронный ресурс
610	1		_aтруды учёных ТПУ
701		1	_aAndreev _bYu. M. _gYury Mikhaylovich
701		1	_aBanerjee _bD.
701		1	_aBernhard _bJ.
701		1	_aBurtsev _bV. E.
701		1	_aChumakov _bA. G. _cphysicist _claboratory assistant-researcher of Tomsk Polytechnic University _f1992- _gAleksandr Grigorjevich _2stltpush _3(RuTPU)RU\TPU\pers\41079
701		1	_aDusaev _bR. R. _cspecialist in the field of nuclear physics _cEngineer of Tomsk Polytechnic University _f1988- _gRenat Ramilyevich _2stltpush _3(RuTPU)RU\TPU\pers\30972
701		1	_aLyubovitskiy (Lyubovitskij) _bV. E. _cphysicist _cProfessor of Tomsk Polytechnic University, Doctor of physical and mathematical sciences, Professor of the University of Tubingen (Germany) _f1963- _gValery Efimovich _2stltpush _3(RuTPU)RU\TPU\pers\33385
701		1	_aTrifonov _bA. Yu. _cphysicist, mathematician _cProfessor of Tomsk Polytechnic University, Doctor of physical and mathematical sciences _f1963- _gAndrey Yurievich _2stltpush _3(RuTPU)RU\TPU\pers\30754
701		1	_aVasilishin _bB. I. _cengineer-physicist _claboratory researcher at Tomsk Polytechnic University _f1990- _gBogdan Ivanovich _2stltpush _3(RuTPU)RU\TPU\pers\37572
712	0	2	_aНациональный исследовательский Томский политехнический университет _bШкола базовой инженерной подготовки _bОтделение математики и информатики _h8031 _2stltpush _3(RuTPU)RU\TPU\col\23555
712	0	2	_aНациональный исследовательский Томский политехнический университет _bИсследовательская школа физики высокоэнергетических процессов _c(2017- ) _h8118 _2stltpush _3(RuTPU)RU\TPU\col\23551
801		2	_aRU _b63413507 _c20230329 _gRCR
856	4		_uhttp://earchive.tpu.ru/handle/11683/74897
856	4		_uhttps://doi.org/10.1103/PhysRevD.104.L111102
942			_cCF