Hunting down the X17 boson at the CERN SPS

• Published in: The European physical journal. C, Particles and fields Vol. 80; no. 12; pp. 1159 - 17
• Main Authors: Depero, E., Andreev, Yu. M., Banerjee, D., Bernhard, J., Burtsev, V. E., Charitonidis, N., Chumakov, A. G., Cooke, D., Crivelli, P., Dermenev, A. V., Donskov, S. V., Dusaev, R. R., Enik, T., Feshchenko, A., Frolov, V. N., Gardikiotis, A., Gerassimov, S. G., Girod, S., Gninenko, S. N., Hösgen, M., Kachanov, V. A., Karneyeu, A. E., Kekelidze, G., Ketzer, B., Kirpichnikov, D. V., Kirsanov, M. M., Kolosov, V. N., Konorov, I. V., Kovalenko, S. G., Kramarenko, V. A., Kravchuk, L. V., Krasnikov, N. V., Kuleshov, S. V., Lyubovitskij, V. E., Lysan, V., Matveev, V. A., Mikhailov, Yu. V., Bueno, L. Molina, Peshekhonov, D. V., Polyakov, V. A., Radics, B., Rojas, R., Rubbia, A., Samoylenko, V. D., Shchukin, D., Sieber, H., Tikhomirov, V. O., Tlisova, vI, Tlisov, D. A., Toropin, A. N., Trifonov, A. Yu, Vasilishin, B. I., Arenas, G. Vasquez, Volkov, P. V., Volkov, V. Yu, Ulloa, P.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2020; Springer; Springer Nature B.V; SpringerOpen
• Subjects: Astronomy; Astrophysics and Cosmology; CERN; Decay; Elementary Particles; Hadrons; Heavy Ions; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Optimization; Parameter sensitivity; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Regular - Experimental Physics; Regular Article - Experimental Physics; String Theory; Synchrotrons
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-020-08725-x

Recently, the ATOMKI experiment has reported new evidence for the excess of e + e - events with a mass ∼ 17 MeV in the nuclear transitions of 4 He, that they previously observed in measurements with 8 Be. These observations could be explained by the existence of a new vector X 17 boson. So far, the search for the decay X 17 → e + e - with the NA64 experiment at the CERN SPS gave negative results. Here, we present a new technique that could be implemented in NA64 aiming to improve the sensitivity and to cover the remaining X 17 parameter space. If a signal-like event is detected, an unambiguous observation is achieved by reconstructing the invariant mass of the X 17 decay with the proposed method. To reach this goal an optimization of the X 17 production target, as well as an efficient and accurate reconstruction of two close decay tracks, is required. A dedicated analysis of the available experimental data making use of the trackers information is presented. This method provides independent confirmation of the NA64 published results [ 1 ], validating the tracking procedure. The detailed Monte Carlo study of the proposed setup and the background estimate show that the goal of the proposed search is feasible.