Phenomenological analysis of associated production of $Z^0+b$ in the $b \rightarrow J/\psi X$ decay channel at the LHC

TL;DR

This paper analyzes the production of Z bosons with non-prompt J/psi particles at the LHC, highlighting the role of single and double parton scatterings and emphasizing the importance of QCD corrections in theoretical models.

Contribution

First phenomenological analysis of Z plus non-prompt J/psi production at NLO, showing limited DPS contribution and emphasizing QCD corrections.

Findings

Data do not strongly indicate significant double parton scattering.

Lower limit of sigma_eff is close to 5 mb.

QCD corrections are crucial for matching ATLAS data.

Abstract

The ATLAS collaboration recently reported on the first observation of associated-production of a $Z^0$ boson with a $J/\psi$. We recently claimed that the corresponding yield of the {\it prompt} $J/\psi$ was dominated by double parton scatterings in the ATLAS acceptance with a somewhat small value of $\sigma_{\rm eff}$. We also found out that single parton scatterings were only dominant at large transverse momenta. We present here the first phenomenological analysis of another part of the ATLAS data sample, namely of a $Z^0$ boson plus a {\it non-prompt} $J/\psi$. Our study is performed at next-to-leading order in $\alpha_s$ and includes parton-shower effects via the {\sc\small MadGraph5_aMC@NLO} framework. We find out that the data, unlike the case of prompt $J/\psi+Z^0$, do not hint at significant DPS contributions. Owing to the current experimental and theoretical uncertainties, there is still a room for these but with a lower limit of $\sigma_{\rm eff}$ close to 5 mb. We stress the importance of QCD corrections to account for the ATLAS data.