Search for a New <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>B</mml:mi><mml:mo>−</mml:mo><mml:mi>L</mml:mi></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>Z</mml:mi><mml:mo>′</mml:mo></mml:msup></mml:math> Gauge Boson with the NA64 Experiment at CERN
Yu. M. Andreev, D. Banerjee, B. Banto Oberhauser, J. Bernhard, P. Bisio, V.E. Burtsev, A. Celentano, N. Charitonidis, А. Г. Чумаков, D. Cooke, P. Crivelli, E. Depero, A. Dermenev, S.V. Donskov, R. R. Dusaev, T. Enik, V. Frolov, A. Gardikiotis, S. Gerassimov, S. Gninenko, M. Hösgen, M. Jeckel, Vassili Kachanov, A. Karneyeu, G. D. Kekelidze, B. Ketzer, D. Kirpichnikov, M. Kirsanov, V. N. Kolosov, S. G. Kovalenko, V. A. Kramarenko, L. Kravchuk, Nikolai Krasnikov, S. Kuleshov, Valery E. Lyubovitskij, V. Lysan, L. Marsicano, V. Matveev, Yu.V. Mikhailov, L. Molina Bueno, D. V. Peshekhonov, V. A. Polyakov, B. Radics, A. Rubbia, K. Salamatin, V. D. Samoylenko, H. Sieber, Dmitry G. Shchukin, Orlando Javier Soto Sandoval, V. O. Tikhomirov, I. Tlisova, A. Toropin, B. I. Vasilishin, P. Volkov, V. Yu. Volkov, I. V. Voronchikhin, J. A. Zamora Saa
Abstract
A search for a new ${Z}^{\ensuremath{'}}$ gauge boson associated with (un)broken $B\ensuremath{-}L$ symmetry in the keV--GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with $3.22\ifmmode\times\else\texttimes\fi{}{10}^{11}$ electrons on target collected during 2016--2021 runs, no signal events were found. This allows us to derive new constraints on the ${Z}^{\ensuremath{'}}\ensuremath{-}e$ coupling strength, which, for the mass range $0.3\ensuremath{\lesssim}{m}_{{Z}^{\ensuremath{'}}}\ensuremath{\lesssim}100\text{ }\text{ }\mathrm{MeV}$, are more stringent compared to those obtained from the neutrino-electron scattering data.