Measurement of the B^+/B^0 Production Ratio from the Upsilon(4S) Meson   using B^+ -> J/psi K^+ and B^0 -> J/psi K^{0}_{S} Decays
  We report a measurement of the production ratio of charged and neutral B mesons from Upsilon(4S) decays based on the ratio of efficiency-corrected yields for the charmonium modes J/psi K^+ and J/psi K^{0}_{S} with 81.9 fb^-1 of data collected with the BABAR detector on the Upsilon(4S) resonance at 10.580 GeV. We find a value of 1.006 +/- 0.036 (stat) +/- 0.031 (sys) for the ratio R^{+/0}=Gamma(Upsilon(4S) -> B^+ B^-)/Gamma(Upsilon(4S)->B^0 B^0bar). 
B. Aubert, et al, BABAR Collaboration