# Triple-parton scatterings in proton–nucleus collisions at high energies

The European Physical Journal C, May 2018

A generic expression to compute triple-parton scattering (TPS) cross sections in high-energy proton–nucleus (pA) collisions is derived as a function of the corresponding single-parton cross sections and an effective parameter encoding the transverse parton profile of the proton. The TPS cross sections are enhanced by a factor of about $$9\,A\simeq 2000$$ in pPb as compared to those in proton–nucleon collisions at the same center-of-mass energy. Estimates for triple charm ($$\mathrm{c}\overline{\mathrm{c}}$$) and bottom ($$\mathrm{b}\overline{\mathrm{b}}$$) production in pPb collisions at LHC and FCC energies are presented based on next-to-next-to-leading-order calculations for $$\mathrm{c}\overline{\mathrm{c}}$$ and $$\mathrm{b}\overline{\mathrm{b}}$$ single-parton cross sections. At $$\sqrt{s_{_{\textsc {nn}}}}= 8.8$$ TeV, about 10% of the pPb events have three $$\mathrm{c}\overline{\mathrm{c}}$$ pairs produced in separate partonic interactions. At $$\sqrt{s_{_{\textsc {nn}}}}= 63$$ TeV, the pPb cross sections for triple-$$J/\psi$$ and triple-$$\mathrm{b}\overline{\mathrm{b}}$$ are $${{\mathscr {O}}}$$(1–10 mb). In the most energetic collisions of cosmic rays in the upper atmosphere, equivalent to $$\sqrt{s_{_{\textsc {nn}}}}\approx$$ 400 TeV, the TPS $$\mathrm{c}\overline{\mathrm{c}}$$ cross section equals the total p–Air inelastic cross section.

This is a preview of a remote PDF: https://link.springer.com/content/pdf/10.1140%2Fepjc%2Fs10052-018-5687-2.pdf

David d’Enterria, Alexander M. Snigirev. Triple-parton scatterings in proton–nucleus collisions at high energies, The European Physical Journal C, 2018, 359, DOI: 10.1140/epjc/s10052-018-5687-2