A compact frozen-spin trap for the search for the electric dipole moment of the muon

A. Adelmann; A. R. Bainbridge; I. Bailey; A. Baldini; S. Basnet; N. Berger; C. Calzolaio; L. Caminada; G. Cavoto; F. Cei; R. Chakraborty; C. Chavez Barajas; M. Chiappini; A. Crivellin; C. Dutsov; A. Ebrahimi; M. Francesconi; L. Galli; G. Gallucci; M. Giovannozzi; H. Goyal; M. Grassi; A. Gurgone; M. Hildebrandt; M. Hoferichter; D. Höhl; T. Hu; T. Hume; J. A. Jaeger; P. Juknevicius; H. C. Kästli; A. Keshavarzi; K. S. Khaw; K. Kirch; A. Kozlinskiy; M. Lancaster; B. Märkisch; L. Morvaj; A. Papa; M. Paraliev; D. Pasciuto; J. Price; F. Renga; M. Sakurai; D. Sanz-Becerra; P. Schmidt-Wellenburg; Y. Z. Shang; Y. Takeuchi; M. E. Tegano; T. Teubner; F. Trillaud; D. Uglietti; D. Vasilkova; A. Venturini; B. Vitali; C. Voena; J. Vossebeld; F. Wauters; G. M. Wong; Y. Zeng

doi:10.1140/epjc/s10052-025-14295-7

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arXiv · 2501.18979

A compact frozen-spin trap for the search for the electric dipole moment of the muon

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Abstract

The electric dipole moments~(EDM) of fundamental particles inherently violate parity~(P) and time-reversal~(T) symmetries. By virtue of the CPT theorem in quantum field theory, the latter also implies the violation of the combined charge-conjugation and parity~(CP) symmetry. We aim to measure the EDM of the muon using the frozen-spin technique within a compact storage trap. This method exploits the high effective electric field, \$E \approx 165\$ MV/m, experienced in the rest frame of the muon with a momentum of about 23 MeV/c when it passes through a solenoidal magnetic field of \$|\vec{B}|=2.5\$ T. In this paper, we outline the fundamental considerations for a muon EDM search and present a conceptual design for a demonstration experiment to be conducted at secondary muon beamlines of the Paul Scherrer Institute in Switzerland. In Phase~I, with an anticipated data acquisition period of 200 days, the expected sensitivity to a muon EDM is 4E-21 ecm. In a subsequent phase, Phase~II, we propose to improve the sensitivity to 6E-23 ecm using a dedicated instrument installed on a different beamline that produces muons of momentum 125 MeV/c}.

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A. Adelmann, A. R. Bainbridge, I. Bailey, A. Baldini, S. Basnet, N. Berger, C. Calzolaio, L. Caminada, G. Cavoto, F. Cei, R. Chakraborty, C. Chavez Barajas, M. Chiappini, A. Crivellin, C. Dutsov, A. Ebrahimi, M. Francesconi, L. Galli, G. Gallucci, M. Giovannozzi, H. Goyal, M. Grassi, A. Gurgone, M. Hildebrandt, M. Hoferichter, D. Höhl, T. Hu, T. Hume, J. A. Jaeger, P. Juknevicius, H. C. Kästli, A. Keshavarzi, K. S. Khaw, K. Kirch, A. Kozlinskiy, M. Lancaster, B. Märkisch, L. Morvaj, A. Papa, M. Paraliev, D. Pasciuto, J. Price, F. Renga, M. Sakurai, D. Sanz-Becerra, P. Schmidt-Wellenburg, Y. Z. Shang, Y. Takeuchi, M. E. Tegano, T. Teubner, F. Trillaud, D. Uglietti, D. Vasilkova, A. Venturini, B. Vitali, C. Voena, J. Vossebeld, F. Wauters, G. M. Wong, Y. Zeng. 2025-01-31. A compact frozen-spin trap for the search for the electric dipole moment of the muon. https://doi.org/10.1140/epjc/s10052-025-14295-7

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