NEW METHOD FOR INVESTIGATING MUONIUM-TO-ANTIMUONIUM CONVERSION

A new method for investigating muonium-to-antimuonium conversion is pr oposed and implemented. The method is based on detecting high-energy e lectrons from the decay of the muon of antimuonim by a wide-aperture m agnetic beta spectrometer. The importance of exploring muonium-to-anti muonium conversion is theoretically substantiated. The setup for the p roposed experiment to study the conversion process is described, and p rocedures for analysis of resulting data and of background conditions at this setup are discussed. With the aid of the proposed method, the probability of muonium-to-antimuonium conversion is investigated exper imentally in a surface-muon beam from the phasotron installed at JINR. New experimental upper limits are obtained for the probability of the conversion process (W(<M(M)over bar>)) and for the weak-interaction c onstant in this process (G(<M(M)over bar>)): W(<M(M)over bar>)less tha n or equal to 47X10(-7) and G(<M(M)over bar>)less than or equal to 0.1 4G(F) (at a 90% C.L.). The mass of the doubly charged Higgs boson H++, which is responsible for the conversion process M-->(M) over bar, is found to be bounded from below as M(++)greater than or equal to 210 Ge V/c(2).