Speaker
Description
A measurement of the fragmentation properties of $\Upsilon(\mathrm{nS})$ mesons inside jets using $138~\mathrm{fb}^{-1}$ of proton--proton collisions at $\sqrt{s} = 13$ TeV is presented. The $\Upsilon(\mathrm{nS})$ mesons are reconstructed via their decays to pairs of oppositely charged muons and are associated with anti-$k_{\mathrm{T}}$ jets if both muons are clustered among the jet constituents and the angular distance between the $\Upsilon(\mathrm{nS})$ candidate and the jet axis is smaller than the jet distance parameter, $R = 0.4$. The longitudinal and transverse projections of the momenta of the $\Upsilon(\mathrm{nS})$ mesons along the momenta of the corresponding jets are studied and corrected for detector effects, and the experimental uncertainties in the measurements are evaluated. The results are compared with Monte Carlo predictions, including recent developments in quarkonia production in parton showers. The description of the data by these Monte Carlo predictions is found to be unsatisfactory, leaving room for improvements in the modelling of such processes.