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^{-}rightarrow langle QQ^{prime }rangle [n] rightarrow Xi _{QQ^{prime }} +bar{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 langle QQ'rangle [n] in P-wave, langle ccrangle [^{1}P_{1}]_{{bar{textbf{3}}}}, langle ccrangle [^{3}P_{J}]_{{textbf{6}}}, langle bcrangle [^{1}P_{1}]_{{bar{textbf{3}}}/ {textbf{6}}}, langle bcrangle [^{3}P_{J}]_{{bar{textbf{3}}}/ {textbf{6}}}, langle bb rangle [^{1}P_{1}]_{{bar{textbf{3}}}}, and langle bbrangle [^{3}P_{J}]_{{textbf{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 langle cc rangle , langle bc rangle , and langle bb rangle 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}}=2.26times 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}textrm{cm}^{-2} textrm{s}^{-1}.