# B-meson production at forward and backward rapidity in $p$+$p$ and Cu+Au collisions at $\sqrt{s_{_{NN}}}$=200 GeV

## TL;DR

This paper measures the fraction of J/ψ mesons originating from B-meson decay in proton-proton and Cu+Au collisions at 200 GeV, revealing insights into heavy-flavor production and nuclear effects at different rapidities.

## Contribution

It provides the first measurement of B-meson decay contribution to J/ψ production at forward and backward rapidity in these collision systems.

## Key findings

- B→J/ψ fraction in p+p is 0.025 ± 0.006 (stat) ± 0.010 (syst).
- B→J/ψ fraction in Cu+Au is approximately 0.09 in both directions.
- Nuclear modification factor of B mesons is consistent with binary scaling in Cu+Au collisions.

## Abstract

The fraction of $J/\psi$ mesons which come from B-meson decay, $\textrm{F}_{B{\rightarrow}J/\psi}$, is measured for J/$\psi$ rapidity \mbox{$1.2<|y|<2.2$} and $p_T>0$ in $p$+$p$ and Cu+Au collisions at $\sqrt{s_{_{NN}}}$=200 GeV with the PHENIX detector. The extracted fraction is $\textrm{F}_{B{\rightarrow}J/\psi}$ = 0.025 $\pm$ 0.006(stat) $\pm$ 0.010(syst) for $p$+$p$ collisions. For Cu+Au collisions, $\textrm{F}_{B{\rightarrow}J/\psi}$ is 0.094 $\pm$ 0.028(stat) $\pm$ 0.037(syst) in the Au-going direction ($-2.2<y<-1.2$) and 0.089 $\pm$ 0.026(stat) $\pm$ 0.040(syst) in the Cu-going direction ($1.2<y<2.2$). The nuclear modification factor, $R_{\rm CuAu}$, of B mesons in Cu+Au collisions is consistent with binary scaling of measured yields in $p$+$p$ at both forward and backward rapidity.