Production of doubly heavy quarkonium associated with two heavy quarks via top quark decays

Abstract

In this paper, we analyze the $1\to 4$ decay channel for the production of doubly heavy quarkonium, $(b\bar{c})$ or $(c\bar{c})$, via top-quark decays, $t\to (b\bar{c})+c+c+\bar{s}$ and $t\to (c\bar{c})+b+c+\bar{s}$, within the framework of nonrelativistic QCD (NRQCD). The dominant contributions are considered in color-singlet S-wave states, i.e., $(b\bar{c}){[}^1{S}_0]$, $(b\bar{c}){[}^3{S}_1]$, $(c\bar{c}){[}^1{S}_0]$, and $(c\bar{c}){[}^3{S}_1]$. Our calculations show that the decay widths for $\overline{B_c}$, $\overline{B_c^{\ast }}$, ${\eta }_c$ and $J/\psi$ production are 0.2251, 0.3099, 0.0537 and 0.0555 MeV, respectively, resulting in $\mathcal{O}(10^4\text{–}10^6)$ level of ${\bar{B}}_c^{(\ast )}$ events and $\mathcal{O}(10^3\text{–}10^5)$ level of charmonium produced at LHC per year. In particular, we find that the dominant contribution to ${\eta }_c$ and $J/\psi$ production via top-quark decays arises from this decay channel proposed in this work. Moreover, this multi-body top-quark decay process can serve as a sensitive probe for validating the narrow-width approximation (NWA). Finally, we provide a detailed analysis of theoretical uncertainties and differential distributions to facilitate the corresponding experimental searches. The production of a hadron associated with three quarks contains rich physical information, providing new insights for the LHC to study $B_c$ mesons and charmonia.

Comments: 7 pages, 3 figures, 2 tables; v2: typo fixed