$\Lambda_b \to \Lambda_c$ Form Factors from QCD Light-Cone Sum Rules

TL;DR

This paper calculates the $ ext{Lambda}_b o ext{Lambda}_c$ transition form factors using light-cone sum rules with $ ext{Lambda}_b$ baryon distribution amplitudes, providing predictions consistent with LHCb data.

Contribution

It introduces a method to compute $ ext{Lambda}_b o ext{Lambda}_c$ form factors with improved handling of baryon states and different distribution amplitude models.

Findings

Predicted form factors and branching fractions align with experimental data.

Provided detailed predictions for polarization and asymmetry observables.

Analyzed the impact of different interpolating currents and DAs models.

Abstract

In this work, 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 $\Lambda_b$-baryon. In the hadronic representation of the correlation function, we have isolated both the $\Lambda_c$ and the $\Lambda_c^*$ states so that the $\Lambda_b \rightarrow \Lambda_c$ form factors can be obtained without ambiguity. We investigate the P-type and A-type current to interpolate the light baryons for a comparison since the interpolation current for the baryon state is not unique. We also employ three parametrization models for DAs of $\Lambda_b $ in the numerical calculation. We present the numerical predictions on the $\Lambda_b \rightarrow \Lambda_c$ form factors and the branching fractions, the averaged forward-backward asymmetry , the averaged final hadron polarization and the averaged lepton polarization of the $\Lambda_b \to \Lambda_c \ell\mu$ decays, as well as the ratio of branching ratios $R_{\Lambda_c}$, and the predicted $R_{\Lambda_c}$ can be consistent with the LHCb data.