Results from Searching for Muonium to Antimuonium Conversion
  A new result from searching for muonium to antimuonium conversion is reported which sets an upper limit on the coupling constant in an assumed $(V-A) \times (V-A)$ type interaction of $G_{M\bar{M}} \leq 3\cdot 10^{-3} G_F$ ~ (90% C.L.).   A particular Z_8 and a minimal 331 GUT model can be ruled out. Further new and stringent limits can be set for masses of bileptonic gauge bosons and $\lambda$ parameters in R-parity breaking supersymmetric models. 
K. Jungmann (1), A. Grossmann (1), J. Merkel (1), V.Meyer(1), G. Zu   Putlitz(1), I. Reinhard(1), K. TR\"Ager(1), P.V. Schmi...