Measurement of $J/\psi$-pair production in $pp$ collisions at $\sqrt{s} = 13$ TeV and study of gluon transverse momentum-dependent PDFs

Journal of High Energy Physics. 2024. Vol. 2024. Article 88.

Aaij R., Abdelmotteleb A. S., Abellan Beteta C., Abudinén F., Ackernley T., Adeva B., Adinolfi M., V. Bocharnikov, A. Boldyrev, M. Hushchyn, F. Ratnikov, A. Ryzhikov

The production cross-section of J/ψ pairs in proton-proton collisions at a centre-of-mass energy of s = 13 TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fb−1 collected by the LHCb experiment. The measurement is performed with both J/ψ mesons in the transverse momentum range 0 < pT < 14 GeV/c and rapidity range 2.0 < y < 4.5. The cross-section of this process is measured to be 16.36 ± 0.28 (stat) ± 0.88 (syst) nb. The contributions from single-parton scattering and double-parton scattering are separated based on the dependence of the cross-section on the absolute rapidity difference ∆y between the two J/ψ mesons. The effective cross-section of double-parton scattering is measured to be σeff = 13.1 ± 1.8 (stat) ± 2.3 (syst) mb. The distribution of the azimuthal angle ϕCS of one of the J/ψ mesons in the Collins-Soper frame and the pT-spectrum of the J/ψ pairs are also measured for the study of the gluon transverse-momentum dependent distributions inside protons. The extracted values of ⟨cos 2ϕCS⟩ and ⟨cos 4ϕCS⟩ are consistent with zero, but the presence of azimuthal asymmetry at a few percent level is allowed.

 

Keywords: машинное обучение, QCD, новая физика, глубокое обучение, Quarkonium, Hadron-Hadron Scattering, анализ данных и искусственный интеллект

Publication based on the results of: Neuromorphic optimization of complex experimental setups at dynamically changing quality metrics and boundary conditions (2024)