Investigation on the photoproduction of bottom-charmed baryon within NRQCD

Abstract

We present a further theoretical study of the orbital $P$-wave bottom-charmed baryon within the framework of nonrelativistic QCD (NRQCD), considering both the direct photoproduction channel $\gamma +\gamma \to {\Xi }_{bc}+\bar{c}+\bar{b}$ and the resolved photoproduction channel $\gamma +g\to {\Xi }_{bc}+\bar{c}+\bar{b}$. At future linear colliders, ILC and CLIC, the initial photons can be emitted from the laser back-scattering (LBS) and then the parton gluon can be emitted from the photon. The formation of ${\Xi }_{bc}$ can be modeled in two-step: a compact diquark state $⟨bc⟩[n]$ is formed first and subsequently captures a light quark from the vacuum to hadronize into the baryon ${\Xi }_{bc}$. The color and spin quantum number $[n]$ of $⟨bc⟩$-diquark can be $[{}^3{S}_1{]}_{\bar{\text{3}}/\text{6}}$, $[{}^1{S}_0{]}_{\bar{\text{3}}/\text{6}}$, $[{}^1{P}_1{]}_{\bar{\text{3}}/\text{6}}$ or $[{}^3{P}_J{]}_{\bar{\text{3}}/\text{6}}$ with $J=0,1,2$. Based on the collision energies and design luminosity of ILC and CLIC, the cross sections, the differential distributions and the estimated produced events of ${\Xi }_{bc}$ baryon have been analyzed. The results show that the contribution of the orbital excited $P$-wave ${\Xi }_{bc}$ baryon can reach 7%-9% of the $S$-wave, providing a non-negligible contributions.

Comments: 13 pages, 2 figures and 4 tables