Production of $B_c$ or $\bar{B}_c$ meson and its excited states via $\bar{t}$-quark or $t$-quark decays
Chao-Hsi Chang, Jian-Xiong Wang, and Xing-Gang Wu

The production of $(b\bar{c})$-quarkonium ($\bar{B}_c$ meson and its excited states) or $(c\bar{b})$-quarkonium ($B_c$ meson and its excited states) via top quark $t$ or top anti-quark $\bar{t}$ decays, $t\to (b\bar{c})+c+W^+$ or $\bar{t}\to (c\bar{b})+\bar{c}+W^-$, respectively is studied within the framework of NRQCD. In addition to the production of the two color-singlet $S$-wave states $|(b\bar{c})(^1S_0)_{\bf 1}\rangle$ or $|(c\bar{b})(^1S_0)_{\bf 1}\rangle$ and $|(b\bar{c})(^3S_1)_{\bf 1}\rangle$ or $|(c\bar{b})(^3S_1)_{\bf 1}\rangle$, the production of the $P$-wave excited $(b\bar{c})$ or $(c\bar{b})$ states, i.e. the four color-singlet $P$-wave states $|(b\bar{c})(^1P_1)_{\bf 1}\rangle$ or $|(c\bar{b})(^1P_1)_{\bf 1}\rangle$, and $(b\bar{c})(^3P_J)_{\bf 1}\rangle$ or $(c\bar{b})(^3P_J)_{\bf 1}\rangle$ (with $J=(1,2,3)$), is also studied. According to the velocity scaling rule of NRQCD, for the production of $P$-wave excited states the contributions from the two color-octet components $|(b\bar{c})(^1S_0)_{\bf 8}\rangle$ or $|(c\bar{b})(^1S_0)_{\bf 8}\rangle$ and $|(b\bar{c})(^3S_1)_{\bf 8}\rangle$ or $|(c\bar{b})(^3S_1)_{\bf 8}\rangle$ are also taken into account. We quantitatively discuss the possibility and the advantages in experimental studies of $B_c$ or $\bar{B}_c$ meson and its excited states via the indirect production at LHC in high luminosity runs and at LHC possible upgraded versions such as SLHC, DLHC, TLHC etc. in future.\\ {\bf PACS numbers:} 12.38.Bx, 14.40.Nd, 14.40.Lb, 14.65.Ha

© 2008 The American Physical Society.