# Toya Tanaka - Spectroscopy of the muonium hyperfine structure

Wednesday, February 27, 2019 from to (US/Central)
at Building 362 ( room F-108 )
 Description Muonium is a bound state of a positive muon and an electron. This characteristic enables a precise QED calculation of its physical properties, and the measurement can be performed with high precision because of its relatively long lifetime and the parity violation when the muon decays. MuSEUM (Muonium Spectroscopy Experiment Using Microwave) collaboration aims to measure the muonium hyperfine structure by using the muon beam line of the J-PARC MLF (Materials and Life science Facility). This precise measurement will be a stringent test of the bound-state QED. By the muonium hyperfine spectroscopy with a high magnetic field, the muon-proton magnetic moment ratio and the muon-electron mass ratio can be extracted as byproducts [1], which the precision are significant to other muon physical properties. The muon-proton magnetic moment ratio is a parameter to decide the muon anomalous magnetic moment, which is known as there is a 3.7 standard deviation discrepancy between the theoretical precision and the experimental result [2][3]. The precision of the muon-electron mass ratio is the dominant uncertainty of the muonium hyperfine structure in theoretical calculation[4]. MuSEUM collaboration succeeded to measure the muonium hyperfine structure with an extremely low magnetic field. We are now continuing this and planning a new measurement with the high magnetic field. In this presentation I would like to overview the measurement status and the R&D for the future high field measurement. 
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