Global properties of proton-proton collisions at $\sqrt{s}$ = 100 TeV

The global properties of the final states produced in hadronic interactions of protons at centre-of-mass energies of future hadron colliders (such as FCC-hh at CERN, and SppC in China), are studied. The predictions of various Monte Carlo (MC) event generators used in collider physics (PYTHIA 6, PYTHIA 8, and PHOJET) and in ultrahigh-energy cosmic-rays studies (EPOS, and QGSJET) are compared. Despite their different underlying modeling of hadronic interactions, their predictions for proton-proton (p-p) collisions at $\sqrt{s}$ = 100 TeV are quite similar. The average of all MC predictions (except PHOJET) for the different observables are: (i) p-p inelastic cross sections ${\sigma }_{\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{l}}$ = 105 $\pm$ 2 mb; (ii) total charged multiplicity ${\mathrm{N}}_{{}_{\mathrm{c}\mathrm{h}}}$ = 150 $\pm$ 20; (iii) charged particle pseudorapidity density at midrapidity $\rm dN_{ch}/d\eta|{\eta=0} = 9.6 \pm 0.2$;(iv)energydensityatmidrapidity$\rm dE/d\eta|{\eta=0} = 13.6 \pm 1.5$GeV,and$\rm dE/d\eta|{\eta=5} = 670 \pm 70$ GeV at the edge of the central region; and (v) average transverse momenta at midrapidities $<{\mathrm{p}}_{\mathrm{T}}>=0.76\pm 0.07$ GeV/c. At midrapidity, EPOS and QGSJET-II predict larger per-event multiplicity probabilities at very low ($\rm N{\rm ch}<3$)andveryhigh($\rm N_{\rm ch}>100$) particle multiplicities, whereas PYTHIA 6 and 8 feature higher yields in the intermediate region $\rm N_{\rm ch}\approx$ 30–80. These results provide useful information for the estimation of the detector occupancies and energy deposits from pileup collisions at the expected large FCC-hh/SppC luminosities.