Fragmentation fractions of two-body b-baryon decays

Abstract

We study the fragmentation fractions $(f_{{\mathbf{B}}_b})$ of the $b$-quark to b-baryons (${\mathbf{B}}_b$). By the assumption of $f_{{\Lambda }_b}/(f_u+f_d)=0.25\pm 0.15$ in accordance with the measurements by LEP, CDF and LHCb Collaborations, we estimate that $f_{{\Lambda }_b}=0.175\pm 0.106$ and $f_{{\Xi }_b^{-,0}}=0.019\pm 0.013$. From these fragmentation fractions, we derive $\mathcal{B}({\Lambda }_b\to J/\psi \Lambda )=(3.3\pm 2.1)\times 10^{-4}$, $\mathcal{B}({\Xi }_b^{-}\to J/\psi {\Xi }^{-})=(5.3\pm 3.9)\times 10^{-4}$ and $\mathcal{B}({\Omega }_b^{-}\to J/\psi {\Omega }^{-})>1.9\times 10^{-5}$. The predictions of $\mathcal{B}({\Lambda }_b\to J/\psi \Lambda )$ and $\mathcal{B}({\Xi }_b^{-}\to J/\psi {\Xi }^{-})$ clearly enable us to test the theoretical models, such as the QCD factorization approach in the $b$-baryon decays.

10 pages, 1 figure, to be published in PLB