Form factors of ω → µ+µ−π0 and ρ → µ+µ− and the dimuon spectrum from NA60
Dimuon yields of the decays η → µ + µ − γ, ω → µ + µ − π 0 and ρ → µ + µ − withcalculated form factors by Terschlüsen and Leupold (2010) and Schneider etal. (2012) were numerically fitted to NA60 data and compared to the resultby Arnaldi et al. (2009). The calculated form factors are theoretically moresound and are an alternative to the previously used pole approximation. Inaddition, the ρ production temperature was reviewed theoretically usingthe ratio of η and ω yields. Several fits were made and the best results wereachieved by using Terschlüsen’s form factor for the ω decay and Schneider’sfor the ρ using two fit parameters less than Arnaldi et al. In addition, theassumption that the yield is the result of only three sources could not bedisproved.
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