New precise measurements of muonium hyperfine structure at J-PARC MUSE

¹ High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
² Department of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
³ Department of Physics, Seoul National University, Seoul 151-742, South Korea
⁴ Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
⁵ Ibaraki University, College of Science, 2-1-1 Bunkyo, Mito 310-8512, Japan
⁶ RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
⁷ Department of Physics, Kyushu University, 744 Motooka, Nishi, Fukuoka, Fukuoka 819-0395, Japan
⁸ Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirane Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
⁹ Physics Department, University of Massachusetts Amherst, Amherst, MA, USA
¹⁰ Department of Physics, Nagoya University, Nagoya 464-8602, Japan
¹¹ TRIUMF, Vancouver, BC V6T 2A3, Canada
¹² International Christian University (ICU), 3-10-2 Osawa, Mitaka, Tokyo 181-8585, Japan
¹³ Cyclotron and Radioisotope Center (CYRIC), Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan
¹⁴ RIKEN, Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
¹⁵ Research Center for Nuclear Physics (RCNP), Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
¹⁶ Radioisotope Laboratory, Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
¹⁷ Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8511, Japan

^* Corresponding author: patrick.strasser(at)kek.jp

Published online: 15 January 2019

Abstract

High precision measurements of the ground state hyperfine structure (HFS) of muonium is a stringent tool for testing bound-state quantum electrodynamics (QED) theory, determining fundamental constants of the muon magnetic moment and mass, and searches for new physics. Muonium is the most suitable system to test QED because both theoretical and experimental values can be precisely determined. Previous measurements were performed decades ago at LAMPF with uncertainties mostly dominated by statistical errors. At the J-PARC Muon Science Facility (MUSE), the MuSEUM collaboration is planning complementary measurements of muonium HFS both at zero and high magnetic field. The new high-intensity muon beam that will soon be available at H-Line will provide an opportunity to improve the precision of these measurements by one order of magnitude. An overview of the different aspects of these new muonium HFS measurements, the current status of the preparation for high-field measurements, and the latest results at zero field are presented.