@article{123652a291724f3fafc19d9d0baf2f7b,
title = "Measurement of J/ψ-pair production in pp collisions at s = 13 TeV and study of gluon transverse-momentum dependent PDFs",
abstract = "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 = "Hadron-Hadron Scattering, Multi-Parton Interactions, QCD, Quarkonium",
author = "\{The LHCb Collaboration\} and Ulrik Egede and Yuki Fujii and Tom Hadavizadeh and Riley Henderson and Lane, \{Jake J.\} and Monk, \{Matthew David\} and Rongrong Song and Eliot Walton and Ward, \{Jake Alexander\} and Williams, \{Mike P.\}",
note = "Funding Information: We would like to thank J.-P. Lansberg, H.-S. Shao, Y.-Q. Ma and L.-P. Sun for the helpful discussions on the quarkonium and quarkonium-pair production, and J.-P. Lansberg, H.-S. Shao, D. Boer, J. Bor, A. Colpani Serri, Z.-G. He and M. A. Nefedov for providing the SPS calculations. We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative staff at the LHCb institutes. We acknowledge support from CERN and from the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MCID/IFA (Romania); MICINN (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (U.S.A.). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), PIC (Spain), GridPP (United Kingdom), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), and Polish WLCG (Poland). We are indebted to the communities behind the multiple open-source software packages on which we depend. Individual groups or members have received support from ARC and ARDC (Australia); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and Sci. \& Tech. Program of Guangzhou (China); Minciencias (Colombia); EPLANET, Marie Sk\textbackslash{}u0142odowska-Curie Actions, ERC and NextGenerationEU (European Union); A*MIDEX, ANR, IPhU and Labex P2IO, and R\textbackslash{}u00E9gion Auvergne-Rh\textbackslash{}u00F4ne-Alpes (France); AvH Foundation (Germany); ICSC (Italy); GVA, XuntaGal, GENCAT, Inditex, InTalent and Prog. Atracci\textbackslash{}u00F3n Talento, CM (Spain); SRC (Sweden); the Leverhulme Trust, the Royal Society and UKRI (United Kingdom). Publisher Copyright: {\textcopyright} The Author(s) 2024.",
year = "2024",
month = mar,
day = "14",
doi = "10.1007/JHEP03(2024)088",
language = "English",
volume = "2024",
journal = "Journal of High Energy Physics",
issn = "1029-8479",
publisher = "Springer-Verlag London Ltd.",
number = "3",
}