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 $\gamma+\gamma \rightarrow \Xi_{bc} +\bar{c}+\bar{b}$ and the resolved photoproduction channel $\gamma+g \rightarrow \Xi_{bc} +\bar{c}+\bar{b}$. 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 $\langle bc\rangle[n]$ 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 $\langle bc\rangle$-diquark can be $[{}^3S_1]_{\bar{\textbf{3}}/\textbf{6}}$, $[{}^1S_0]_{\bar{\textbf{3}}/\textbf{6}}$, $[{}^1P_1]_{\bar{\textbf{3}}/\textbf{6}}$ or $[{}^3P_J]_{\bar{\textbf{3}}/\textbf{6}}$ 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.