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Search for vector mediator of dark matter production in invisible decay mode
Journal
Physical Review D
Date Issued
2018-04-01
Author(s)
Banerjee, D.
Burtsev, V. E.
Chumakov, A. G.
Cooke, D.
Crivelli, P.
Depero, E.
Dermenev, A. V.
Donskov, S. V.
Dubinin, F.
Dusaev, R. R.
Emmenegger, S.
Fabich, A.
Frolov, V. N.
Gardikiotis, A.
Gerassimov, S. G.
Gninenko, S. N.
Hösgen, M.
Karneyeu, A. E.
Ketzer, B.
Kirpichnikov, D. V.
Kirsanov, M. M.
Konorov, I. V.
Kramarenko, V. A.
Kravchuk, L. V.
Krasnikov, N. V.
Lysan, V.
Matveev, V. A.
Mikhailov, Yu V.
Peshekhonov, D. V.
Polyakov, V. A.
Radics, B.
Rojas, R.
Rubbia, A.
Samoylenko, V. D.
Tikhomirov, V. O.
Tlisov, D. A.
Toropin, A. N.
Trifonov, A. Yu
Vasilishin, B. I.
Vasquez Arenas, G.
Ulloa, P.
Abstract
A search is performed for a new sub-GeV vector boson (A0
) mediated production of dark matter (χ) in the
fixed-target experiment, NA64, at the CERN SPS. The A0
, called dark photon, can be generated in the
reaction e−Z → e−ZA0 of 100 GeV electrons dumped against an active target followed by its prompt
invisible decay A0 → χχ¯. The experimental signature of this process would be an event with an isolated
electron and large missing energy in the detector. From the analysis of the data sample collected in 2016
corresponding to 4.3 × 1010 electrons on target no evidence of such a process has been found. New
stringent constraints on the A0 mixing strength with photons, 10−5 ≲ ϵ ≲ 10−2, for the A0 mass range
mA0 ≲ 1 GeV are derived. For models considering scalar and fermionic thermal dark matter interacting with
the visible sector through the vector portal the 90% C.L. limits 10−11 ≲ y ≲ 10−6 on the dark-matter
parameter y ¼ ϵ2αDð
mχ
mA0
Þ4 are obtained for the dark coupling constant αD ¼ 0.5 and dark-matter masses
0.001 ≲ mχ ≲ 0.5 GeV. The lower limits αD ≳ 10−3 for pseudo-Dirac dark matter in the mass region
mχ ≲ 0.05 GeV are more stringent than the corresponding bounds from beam dump experiments. The
results are obtained by using exact tree level calculations of the A0 production cross sections, which turn out
to be significantly smaller compared to the one obtained in the Weizsäcker-Williams approximation for the
mass region mA0 ≳ 0.1 GeV.
) mediated production of dark matter (χ) in the
fixed-target experiment, NA64, at the CERN SPS. The A0
, called dark photon, can be generated in the
reaction e−Z → e−ZA0 of 100 GeV electrons dumped against an active target followed by its prompt
invisible decay A0 → χχ¯. The experimental signature of this process would be an event with an isolated
electron and large missing energy in the detector. From the analysis of the data sample collected in 2016
corresponding to 4.3 × 1010 electrons on target no evidence of such a process has been found. New
stringent constraints on the A0 mixing strength with photons, 10−5 ≲ ϵ ≲ 10−2, for the A0 mass range
mA0 ≲ 1 GeV are derived. For models considering scalar and fermionic thermal dark matter interacting with
the visible sector through the vector portal the 90% C.L. limits 10−11 ≲ y ≲ 10−6 on the dark-matter
parameter y ¼ ϵ2αDð
mχ
mA0
Þ4 are obtained for the dark coupling constant αD ¼ 0.5 and dark-matter masses
0.001 ≲ mχ ≲ 0.5 GeV. The lower limits αD ≳ 10−3 for pseudo-Dirac dark matter in the mass region
mχ ≲ 0.05 GeV are more stringent than the corresponding bounds from beam dump experiments. The
results are obtained by using exact tree level calculations of the A0 production cross sections, which turn out
to be significantly smaller compared to the one obtained in the Weizsäcker-Williams approximation for the
mass region mA0 ≳ 0.1 GeV.
Subjects
