Measurement of the form-factor ratios for D-s(+)->phi l(+)nu(l)

We have measured the form factor ratios r(V) = V(0)/A(1)(0) and r(2) = A(2) (0)/A(1)(0) for the decay D-s + --> phi l(+) nu(l), phi --> K+ K-, using da ta from charm hadroproduction experiment E791 at Fermilab. Results are base d on 144 signal and 22 background events in the electron channel and 127 si gnal and 34 background events in the muon channel. We combine the measureme nts from both lepton channels to obtain r(V) = 2.27 +/- 0.22 and r(2) = 1.5 7 +/- 0.25 +/- 0.19. (C) 1999 by Elsevier Science B.V. All rights reserved.