Semileptonic decay Lambda_c-->Lambda \ell^+ \nu from QCD light-cone sum rules

Abstract

We present the study of the semileptonic decay \Lambda_c to \Lambda\ell^+\nu by using the light-cone sum rule approach. Distribution amplitudes (DAs) for the \Lambda baryon are discussed to the leading order conformal spin, and QCD sum rule estimate for the corresponding parameters is presented. The form factors describing the decay are calculated and used to predict the decay width and the decay asymmetry parameter \alpha. With the inclusion of twist-3 contributions the calculated decay width \Gamma=(7.2+/-2.0)X10^{-14} GeV as well as asymmetry \alpha=-(0.88+/-0.03) is found in good agreement with the experimental data, while there are appreciable deviations from experiment values when the higher twist contributions are included.

Comments: RevTex4, 8 pages, 5 figures, misprints corrected, mini changes in numerical results