Semileptonic decays of ${\Lambda }_c^{+}$ in dynamical approaches

Abstract

We study the semileptonic decays of ${\Lambda }_c^{+}\to \Lambda (n){\ell }^{+}{\nu }_{\ell }$ in two relativistic dynamical approaches of the light-front constituent quark model (LFCQM) and MIT bag model (MBM). By considering the Fermi statistic between quarks and determining spin-flavor structures in baryons along with the helicity formalism in the two different dynamical models, we calculate the branching ratios ($\mathcal{B}$s) and averaged asymmetry parameters ($\alpha$s) in the decays. Explicitly, we find that $\mathcal{B}({\Lambda }_c^{+}\to \Lambda e^{+}{\nu }_e)=(3.36\pm 0.87,3.48)\%$ and $\alpha ({\Lambda }_c^{+}\to \Lambda e^{+}{\nu }_e)=(-0.97\pm 0.03,-0.83)$ in (LFCQM, MBM), in comparison with the data of $\mathcal{B}({\Lambda }_c^{+}\to \Lambda e^{+}{\nu }_e)=(3.6\pm 0.4)\%$ and $\alpha ({\Lambda }_c^{+}\to \Lambda e^{+}{\nu }_e)=-0.86\pm 0.04$ given by the Particle Data Group, respectively. We also predict that $\mathcal{B}({\Lambda }_c^{+}\to n{e}^{+}{\nu }_e)=(0.57\pm 0.15,3.6\pm 1.5)\times 10^{-3}$ and $\alpha ({\Lambda }_c^{+}\to n{e}^{+}{\nu }_e)=(-0.98\pm 0.02,-0.96\pm 0.04)$ in LFCQM with two different scenarios for the momentum distributions of quarks in the neutron, and $\mathcal{B}({\Lambda }_c^{+}\to n{e}^{+}{\nu }_e)=0.279\times 10^{-2}$ and $\alpha ({\Lambda }_c^{+}\to n{e}^{+}{\nu }_e)=-0.87$ in MBM, which could be tested by the ongoing experiments at BESIII, LHCb and BELLEII.

Comments: 22 pages, 5 figures, revised version accepted by PRD