Production of Excited Doubly Heavy Baryons at the Super-$Z$ Factory

Abstract

In the framework of nonrelativistic QCD, the excited doubly heavy baryons are thoroughly studied via the channel $e^{+}{e}^{-}\to ⟨Q{Q}^{\prime }⟩[n]\to {\Xi }_{Q{Q}^{\prime }}+\overline{Q^{\prime }}+\bar{Q}$, which takes place at the collision energy $Z$-pole. $Q^{(\prime )}$ represents $b$ or $c$ quark for the production of ${\Xi }_{cc}$, ${\Xi }_{bc}$, and ${\Xi }_{bb}$, respectively. All of the intermediate diquark states $⟨Q{Q}^{\prime }⟩[n]$ in $P$-wave, $⟨cc⟩{[}^1{P}_1{]}_{\bar{3}}$, $⟨cc⟩{[}^3{P}_J{]}_6$, $⟨bc⟩{[}^1{P}_1{]}_{\bar{3}/6}$, $⟨bc⟩{[}^3{P}_J{]}_{\bar{3}/6}$, $⟨bb⟩{[}^1{P}_1{]}_{\bar{3}}$, and $⟨bb⟩{[}^3{P}_J{]}_6$ with $J=0$, 1, or 2, are taken into account. The cross sections and differential distributions, including the transverse momentum, rapidity, angular, and invariant mass, are discussed for the excited baryons production. We find that the contributions of $⟨cc⟩$, $⟨bc⟩$, and $⟨bb⟩$ in $P$-wave are found to be 3.97$\%$, 5.08$\%$, and 5.89$\%$, respectively, compared to $S$-wave. Supposing that all excited states can decay into the ground state 100\%, the total events $N_{{\Xi }_{cc}}=8.48\times 10^{4-6}$, $N_{{\Xi }_{bc}}=2.26\times 10^{5-7}$, and $N_{{\Xi }_{bb}}=4.12\times 10^{3-5}$ would be produced at the Super-$Z$ Factory with a high luminosity up to $\mathcal{L}\simeq 10^{34-36}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$.

Comments: 15 pages, 4 figures, 5 tables, version to be published in EPJC