Doubly-charmed baryon production in $Z$ boson decay

Abstract

In this paper, we carry out a detailed study of doubly-charmed baryon production in $Z$ boson decay, on the basis of the nonrelativistic QCD factorization. With the inclusion of the di-quark states $(cc){[}^3{S}_1{]}_{\bar{\text{3}}}$ and $(cc){[}^1{S}_0{]}_{\text{6}}$, the branching ratio of ${\mathcal{B}}_{Z\to {\Xi }_{cc}+X}$ is predicted to be of the $10^{-5}$ order, indicating its experimental measurability. By comparing to the ${\Lambda }_c^{+}$ yield in $Z$ decay, we predict ${\mathcal{R}}_{{\Xi }_{cc}^{+}}(=\frac{\Gamma (Z\to {\Xi }_{cc}^{+})\times \mathcal{B}({\Xi }_{cc}^{+}\to {\Lambda }_c^{+}{K}^{-}{\pi }^{+})}{\Gamma (Z\to {\Lambda }_c^{+})})=(0.85_{-0.07}^{+0.10})\times 10^{-4}$ and ${\mathcal{R}}_{{\Xi }_{cc}^{++}}(=\frac{\Gamma (Z\to {\Xi }_{cc}^{++})\times \mathcal{B}({\Xi }_{cc}^{++}\to {\Lambda }_c^{+}{K}^{-}{\pi }^{+}{\pi }^{+})}{\Gamma (Z\to {\Lambda }_c^{+})})=(1.70_{-0.14}^{+0.20})\times 10^{-4}$, which are at clear variance with the SELEX measurements but comparable with the values given by the LHCb and Belle collaborations.

v1: 14pages, 2 figures, and 1 table; v2: references added