Production of $B_c$ or ${\bar{B}}_c$ meson and its excited states via $\bar{t}$-quark or $t$-quark decays

Abstract

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 $|(b\bar{c}){(}^1{S}_0{)}_1>$ or $|(c\bar{b}){(}^1{S}_0{)}_1>$ and $|(b\bar{c}){(}^3{S}_1{)}_1>$ or $|(c\bar{b}){(}^3{S}_1{)}_1>$, the production of the $P$-wave excited $(b\bar{c})$ or $(c\bar{b})$ states, i.e. the four color-singlet $P$-wave states $|(b\bar{c}){(}^1{P}_1{)}_1>$ or $|(c\bar{b}){(}^1{P}_1{)}_1>$, and $(b\bar{c}){(}^3{P}_J{)}_1>$ or $(c\bar{b}){(}^3{P}_J{)}_1>$ (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 $|(b\bar{c}){(}^1{S}_0{)}_8>$ or $|(c\bar{b}){(}^1{S}_0{)}_8>$ and $|(b\bar{c}){(}^3{S}_1{)}_8>$ or $|(c\bar{b}){(}^3{S}_1{)}_8>$ 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.

39 pages, 3 figures, regular paper

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