Measurement of the prompt J/ $\psi $ pair production cross-section in pp collisions at $\sqrt{s} = 8$  TeV with the ATLAS detector

• Autor(a) principal: ATLAS collaboration (2854 authors)
• Data de Publicação: 2017
• Outros Autores: Aguilar-Saavedra, Juan Antonio, Amor Dos Santos, Susana Patricia, Anjos, Nuno, Araque, Juan Pedro, Carvalho, João, Castro, Nuno Filipe, Conde Muiño, Patricia, Da Cunha Sargedas De Sousa, Mario Jose, Fiolhais, Miguel, Galhardo, Bruno, Gomes, Agostinho, Gonçalo, Ricardo, Jorge, Pedro, Machado Miguens, Joana, Maio, Amélia, Maneira, José, Oleiro Seabra, Luis Filipe, Onofre, António, Pedro, Rute, Santos, Helena, Saraiva, João, Silva, José, Tavares Delgado, Ademar, Veloso, Filipe, Wolters, Helmut
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Texto Completo: http://dx.doi.org/10.1140/epjc/s10052-017-4644-9; http://hdl.handle.net/10400.26/27250

The production of two prompt $J/\psi $ mesons, each with transverse momenta $p_{\mathrm {T}}>8.5$  GeV and rapidity $|y| < 2.1$ , is studied using a sample of proton-proton collisions at $\sqrt{s} = 8$  TeV, corresponding to an integrated luminosity of 11.4 fb$^{-1}$ collected in 2012 with the ATLAS detector at the LHC. The differential cross-section, assuming unpolarised $J/\psi $ production, is measured as a function of the transverse momentum of the lower- $p_{\mathrm {T}}$ $J/\psi $ meson, di- $J/\psi $ $p_{\mathrm {T}}$ and mass, the difference in rapidity between the two $J/\psi $ mesons, and the azimuthal angle between the two $J/\psi $ mesons. The fraction of prompt pair events due to double parton scattering is determined by studying kinematic correlations between the two $J/\psi $ mesons. The total and double parton scattering cross-sections are compared with predictions. The effective cross-section of double parton scattering is measured to be $\sigma _{\mathrm {eff}} = 6.3 \pm 1.6 \mathrm {(stat)} \pm 1.0 \mathrm {(syst)}$  mb.