New Insights into $J/ψ$ and $ψ(2S)$ Production at 13 TeV

The LHCb collaboration has reported new measurements regarding the production of the $J/ψ$ and $ψ(2S)$ particles in proton-proton collisions at a center-of-mass energy of $13$ TeV. These measurements were conducted using data collected between 2016 and 2018. The study focused on the exclusive production processes where the $J/ψ$ decays into two muons ($μ^+μ^-$) and similarly for the $ψ(2S)$ particle.

The integrated cross-section for the $J/ψ$ production was measured to be:

[ \sigma_{J/ψ\toμ^+μ^-}(2.0<y_{J/ψ}<4.5,2.0<η_{μ^±}<4.5) = 400 \pm 2 \pm 5 \pm 12 \,\text{pb} ]\

For the $ψ(2S)$, the cross-section was found to be:

[ \sigma_{ψ(2S)\toμ^+μ^-}(2.0<y_{ψ(2S)}<4.5,2.0<η_{μ^±}<4.5) = 9.40 \pm 0.15 \pm 0.13 \pm 0.27 \,\text{pb} ]\

The uncertainties in these measurements include statistical, systematic, and those related to luminosity determination. Additionally, the ratio of the cross-sections for the $ψ(2S)$ to the $J/ψ$ was calculated, yielding:

[ \frac{\sigma_{ψ(2S)}}{\sigma_{J/ψ}} = 0.1763 \pm 0.0029 \pm 0.0008 \pm 0.0039 ]\

This study also marks the first time the dependence of the cross-sections on the total transverse momentum transfer has been determined in proton-proton collisions, showing consistency with previous observations in electron-proton collisions. The findings contribute to a deeper understanding of particle production mechanisms in high-energy physics and may have implications for future research in the field.

The full paper titled "Measurement of exclusive $J/ψ$ and $ψ(2S)$ production at $\sqrt{s}=13$ TeV" can be accessed here and was authored by the LHCb collaboration, including R. Aaij and over a thousand co-authors.