Limit on a right-handed admixture to the weak b → c current from semileptonic decays

We determine an upper bound for a possible right-handed b -> c quark current admixture in semileptonic (B) over bar -> X(c)l(-)(v) over bar decays from a simultaneous fit to moments of the lepton-energy and hadronic-mass distribution measured as a function of the lower limit on the lepton energy, using data measured by the BABAR detector. The right-handed admixture is parametrized by a new parameter c(R) as coefficient of computed moments with right-handed quark current. For the standard-model part we use the prediction of the heavy-quark expansion up to order 1/m(b)(3) and perturbative corrections and for the right-handed contribution only up to order 1/m(b)(2) and perturbative corrections. We find c(R)' = 0.05(-0.50)(+0.33) in agreement with the standard-model prediction of zero. Additionally, we give a constraint on a possible right-handed admixture from exclusive decays, which is with a value of c(R)' = 0.01 +/- 0.03 more restrictive than our value from the inclusive fit. The difference in vertical bar V-cb vertical bar between the inclusive and exclusive extraction is only slightly reduced when allowing for a right-handed admixture in the range of c(R)' = 0.01 +/- 0.03.