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arXiv · 2404.06982

First constraints on the $L_\mu-L_\tau$ explanation of the muon $g-2$ anomaly from NA64-$e$ at CERN

Yu. M. Andreev·A. Antonov·D. Banerjee·B. Banto Oberhauser·J. Bernhard·P. Bisio·A. Celentano·N. Charitonidis·D. Cooke·P. Crivelli·E. Depero·A. V. Dermenev·S. V. Donskov·R. R. Dusaev·T. Enik·V. N. Frolov·A. Gardikiotis·S. N. Gninenko·M. Hösgen·V. A. Kachanov·Y. Kambar·A. E. Karneyeu·G. Kekelidze·B. Ketzer·D. V. Kirpichnikov·M. M. Kirsanov·V. N. Kolosov·S. V. Gertsenberger·S. Girod·E. A. Kasianova·V. A. Kramarenko·L. V. Kravchuk·N. V. Krasnikov·S. V. Kuleshov·V. E. Lyubovitskij·V. Lysan·A. Marini·L. Marsicano·V. A. Matveev·R. Mena Fredes·R. Mena Yanssen·L. Molina Bueno·M. Mongillo·D. V. Peshekhonov·V. A. Polyakov·B. Radics·K. Salamatin·V. D. Samoylenko·H. Sieber·D. Shchukin·O. Soto·V. O. Tikhomirov·I. Tlisova·A. N. Toropin·M. Tuzi·P. Ulloa·P. V. Volkov·V. Yu. Volkov·I. V. Voronchikhin·J. Zamora-Saá·A. S. Zhevlako
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Abstract

The inclusion of an additional $U(1)$ gauge $L_\mu-L_\tau$ symmetry would release the tension between the measured and the predicted value of the anomalous muon magnetic moment: this paradigm assumes the existence of a new, light $Z^\prime$ vector boson, with dominant coupling to $\mu$ and $\tau$ leptons and interacting with electrons via a loop mechanism. The $L_\mu-L_\tau$ model can also explain the Dark Matter relic abundance, by assuming that the $Z'$ boson acts as a "portal" to a new Dark Sector of particles in Nature, not charged under known interactions. In this work we present the results of the $Z'$ search performed by the NA64-$e$ experiment at CERN SPS, that collected $\sim 9\times10^{11}$ 100 GeV electrons impinging on an active thick target. Despite the suppressed $Z'$ production yield with an electron beam, NA64-$e$ provides the first accelerator-based results excluding the $g-2$ preferred band of the $Z'$ parameter space in the 1 keV $ < m_{Z'} \lesssim 2$ MeV range, in complementarity with the limits recently obtained by the NA64-$\mu$ experiment with a muon beam.

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Yu. M. Andreev, A. Antonov, D. Banerjee, B. Banto Oberhauser, J. Bernhard, P. Bisio, A. Celentano, N. Charitonidis, D. Cooke, P. Crivelli, E. Depero, A. V. Dermenev, S. V. Donskov, R. R. Dusaev, T. Enik, V. N. Frolov, A. Gardikiotis, S. N. Gninenko, M. Hösgen, V. A. Kachanov, Y. Kambar, A. E. Karneyeu, G. Kekelidze, B. Ketzer, D. V. Kirpichnikov, M. M. Kirsanov, V. N. Kolosov, S. V. Gertsenberger, S. Girod, E. A. Kasianova, V. A. Kramarenko, L. V. Kravchuk, N. V. Krasnikov, S. V. Kuleshov, V. E. Lyubovitskij, V. Lysan, A. Marini, L. Marsicano, V. A. Matveev, R. Mena Fredes, R. Mena Yanssen, L. Molina Bueno, M. Mongillo, D. V. Peshekhonov, V. A. Polyakov, B. Radics, K. Salamatin, V. D. Samoylenko, H. Sieber, D. Shchukin, O. Soto, V. O. Tikhomirov, I. Tlisova, A. N. Toropin, M. Tuzi, P. Ulloa, P. V. Volkov, V. Yu. Volkov, I. V. Voronchikhin, J. Zamora-Saá, A. S. Zhevlako. 2024-04-10. First constraints on the $L_\mu-L_\tau$ explanation of the muon $g-2$ anomaly from NA64-$e$ at CERN. https://arxiv.org/abs/2404.06982

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