Λb → Λc form factors from QCD light-cone sum rules

In this study, we calculate the transition form factors of Lambda(b) decaying into Lambda(c) within the framework of light-cone sum rules with the distribution amplitudes (DAs) of the Lambda(b)-baryon. In the hadronic representation of the correlation function, we isolate both the Lambda(c) and Lambda(c)* states so that the Lambda(b) -> Lambda(c) form factors can be obtained without ambiguity. We investigate the P-type and A-type currents to interpolate light baryons for comparison because the interpolation current for the baryon state is not unique. We also employ three parametrization models for the DAs of Lambda(b) in the numerical calculation. We present the numerical predictions for the Lambda(b) -> Lambda(c) form factors and branching fractions, averaged forward-backward asymmetry, averaged final hadron polarization, and averaged lepton polarization of the Lambda(b) ->Lambda(c)l mu decays, as well as the ratio of the branching ratios R-Lambda c. The predicted R-Lambda c is consistent with LHCb data.

Automated summary

In this study, we calculate the transition form factors of Lambda(b) decaying into Lambda(c) using the framework of light-cone sum rules. We investigate different interpolation currents and distribution amplitude models, and present numerical predictions consistent with experimental data.