Analysis of rhoomega interference in the pion formfactor.pdf

Published in Phys. Lett. B376 (1996) 19. ADP-95-50/T197 hep-ph/9601309 Analysis of rho-omega interference in the pion form-factor 6 9 9 1 Kim Maltmana,b , H.B. O’Connellb and A.G. Williamsb,c g u A 9 a Department of Mathematics and Statistics, York University, 4700 Keele St., 1 2 North York, Ontario, Canada M3J 1P3 v b 9 Department of Physics and Mathematical Physics, University of Adelaide 5005, 0 3 Australia 1 0 c 6 Institute for Theoretical Physics, University of Adelaide 5005, Australia 9 / h p - 14 February, 1996 p e h : v i X Abstract r a The formalism underlying the analysis of e+e− → π+π− in the ρ − ω in- terference region is carefully revisited. We show that the standard neglect of the pure I = 0 omega, ωI , “direct” coupling to ππ is not valid, and ex- tract those combinations of the direct coupling and ρ-ω mixing allowed by experiment. The latter is shown to be only very weakly constrained by ex- periment, and we conclude that data from the e+e− → π+π− interference region cannot be used to fix the value of ρ−ω mixing in a model-independent way unless the errors on the experimental phase can be significantly re- duced. Certain other modifications of the usual formalism necessitated by the unavoidable momentum-dependence of ρ−ω mixing are also discussed. E-mail: hoconnel, awilliam@physics.adelaide.edu.au; FS300175@sol.yo