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

TL;DR

This paper investigates the production of $B_c$ and $ar{B}_c$ mesons and their excited states via top quark decays using NRQCD, highlighting potential experimental detection at current and future LHC runs.

Contribution

It provides a comprehensive theoretical analysis of $B_c$ meson production, including excited states and color-octet contributions, within the NRQCD framework, for the first time in this context.

Findings

Quantitative estimates of $B_c$ and excited state production rates.

Analysis of experimental prospects at LHC and future colliders.

Inclusion of color-octet contributions in production calculations.

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 $|(b\bar{c})(^1S_0)_{\bf 1}>$ or $|(c\bar{b})(^1S_0)_{\bf 1}>$ and $|(b\bar{c})(^3S_1)_{\bf 1}>$ or $|(c\bar{b})(^3S_1)_{\bf 1}>$, the production of the $P$-wave excited $(b\bar{c})$ or $(c\bar{b})$ states, i.e. the four color-singlet $P$-wave states $|(b\bar{c})(^1P_1)_{\bf 1}>$ or $|(c\bar{b})(^1P_1)_{\bf 1}>$, and $(b\bar{c})(^3P_J)_{\bf 1}>$ or $(c\bar{b})(^3P_J)_{\bf 1}>$ (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 $|(b\bar{c})(^1S_0)_{\bf 8}>$ or $|(c\bar{b})(^1S_0)_{\bf 8}>$ and $|(b\bar{c})(^3S_1)_{\bf 8}>$ or $|(c\bar{b})(^3S_1)_{\bf 8}>$ 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.