Improved measurement of the form factors in the decay Lambda(+)(c) -> Lambda e(+)nu(e)

Abstract

Using the CLEO detector at the Cornell Electron Storage Ring, we have studied the distribution of kinematic variables in the decay Lambda(c)(+)->Lambda e(+)nu(e). By performing a four-dimensional maximum likelihood fit, we determine the form factor ratio, R=f(2)/f(1)=-0.31 +/- 0.05(stat)+/- 0.04(syst), the pole mass, M-pole=[2.21 +/- 0.08(stat)+/- 0.14(syst)] GeV/c(2), and the decay asymmetry parameter of the Lambda(c)(+), alpha(Lambda c)=-0.86 +/- 0.03(stat)+/- 0.02(syst), for < q(2)>=0.67 (GeV/c(2))(2). We compare the angular distributions of the Lambda(c)(+) and (Lambda) over bar (-)(c) and find no evidence for CP violation: A(Lambda c)=(alpha(Lambda c)+alpha((Lambda) over barc))/(alpha(Lambda c)-alpha((Lambda) over barc))=0.00 +/- 0.03(stat)+/- 0.01(syst)+/- 0.02, where the third error is from the uncertainty in the world average of the CP-violating parameter, A(Lambda), for Lambda -> p pi(-).