$$\Lambda _b \rightarrow p, N^*(1535)$$ form factors from QCD light-cone sum rules

Abstract

In this work, we calculate the transition form factors of $$\Lambda _b$$ Λ b decaying into proton and $$N^*(1535)$$ N ∗ ( 1535 ) ($$J^P={1/2}^+$$ J P = 1 / 2 + and $${1/2}^-$$ 1 / 2 - respectively) within the framework of light-cone sum rules with the distribution amplitudes (DAs) of $$\Lambda _b$$ Λ b -baryon. In the hadronic representation of the correlation function, we have isolated both the proton and the $$N^*(1535)$$ N ∗ ( 1535 ) states so that the $$\Lambda _b \rightarrow p, N^*(1535)$$ Λ b → p , N ∗ ( 1535 ) form factors can be evaluated simultaneously. Due to the less known properties of the baryons, we investigate three interpolating currents of the light baryons and five parametrization models for DAs of $$\Lambda _b $$ Λ b . Numerically, our predictions on the $$\Lambda _b \rightarrow p$$ Λ b → p form factors and the branching fractions of $$\Lambda _b\rightarrow p\ell \nu $$ Λ b → p ℓ ν from the Ioffe or the tensor currents are consistent with the Lattice simulation and the results from the light-baryon sum rules, as well as the experimental data of $$Br(\Lambda _b^0\rightarrow p\mu ^-{{\bar{\nu }}})$$ B r ( Λ b 0 → p μ - ν ¯ ) . The predictions on the form factors of $$\Lambda _b \rightarrow N^*(1535)$$ Λ b → N ∗ ( 1535 ) are very sensitive to the choice of the interpolating currents so that the relevant measurement could be helpful to clarify the properties of baryons.

Light-cone distribution amplitudes of a light baryon in large-momentum effective theory

“…Though many progresses have been made in obtaining the LCDAs of a nucleon in the past decades [3][4][5][6][7][8][9][10][11][12][13][14][15][16], most of the available analyses are limited to the few lowest moments of LCDAs. Due to the lack of a complete knowledge of baryon LCDAs, many phenomenological analyses adopt model paramterizations resulting in uncontrollable errors in theoretical predictions for decay branching fractions of heavy baryons [17][18][19]. Thus, it is highly indispensable to develop a method to calculate the full shape of baryon LCDAs from the first principle of QCD.…”