Measurement of B -> D Form Factors in the Semileptonic Decay B -> D* l nu at BaBar

We present here the results of a measurement of the three semileptonic form factors involved in the decay B{sup 0} {yields} D*{ell}{nu}, where {ell} is one of the two light charged leptons (i.e. an electron or muon--though the final results in this work are determined only for {ell} = electron). This measurement uses the Babar 2000-2002 data set, which is altogether approximately 85 x 10{sup 6} B{bar B}-pairs in 78 fb{sup -1} of integrated luminosity. The D*{sup +} was reconstructed in the channel D*{sup +} {yields} D{sup 0}{pi}{sup +}, and the D{sup 0} in the channel D{sup 0} {yields} K{sup -}{pi}{sup +}. This analysis was based ultimately on {approx} 16,386 reconstructed events with an estimated background contamination of {approx} 15%. The method of the measurement was to perform a unbinned maximum likelihood fit in the four kinematic variables that describe the decay for the three form factor parameters R{sub 1}, R{sub 2}, and {rho}{sup 2}. The results obtained for the form factor ratios are R{sub 1} = 1.328 {+-} 0.055 {+-} 0.025 {+-} 0.025 and R{sub 2} = 0.920 {+-} 0.044 {+-} 0.020 {+-} 0.013 for the ratios and {rho}{sup 2} = 0.769 {+-} 0.039 {+-} 0.019 {+-} 0.032 for the form factor slope. The errors given are statistical, Monte Carlo statistical and systematic respectively