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

Abstract

Abstract: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 ultrahighenergy 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 √ 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 σ inel = 105 ± 2 mb; (ii) total charged multiplicity N ch = 150 ± 20; (iii) charged particle pseudorapidity density at midrapidity dN ch /dη| η=0 = 9.6 ± 0.2; (iv) energy density at midrapidity dE/dη| η=0 = 13.6 ± 1.5 GeV, and dE/dη| η=5 = 670 ± 70 GeV at the edge of the central region; and (v) average transverse momenta at midrapidities p T = 0.76 ± 0.07 GeV/c. At midrapidity, epos and qgsjet-ii predict larger per-event multiplicity probabilities at very low (N ch < 3) and very high (N ch > 100) particle multiplicities, whereas pythia 6 and 8 feature higher yields in the intermediate region N ch ≈ 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.

Average event properties from LHC to FCC-hh

“…As a cross check, the fully inclusive distributions were also calculated, but the inclusion of neutrinos and muons only give rise to per-mille level differences. We note that our benchmark predictions for the Monash tune of Pythia are consistent 7 with the earlier study of [13]. We emphasise that although [13] considered a similar set of observables to ours, they were mainly concerned with the differences between a range of qualitatively different generators, while our study primarily addresses how the modelling uncertainties for Pythia scale with energy.…”

“…It is complementary to the that of [13] which considered extrapolations of the default predictions (i.e., without parameter variations) of several qualitatively different MC models of soft-inclusive QCD reactions, including Epos [14], Phojet [15], and Qgsjet [16]. We verify that we obtain consistent results for the common reference model considered in both studies (default Pythia 8.2), and note that most of the models considered in [13] exhibit a rather similar scaling behaviour of, e.g., the central charged-particle densities over the extrapolated region, predicting that it should grow by about a factor of 2 from 10 to 100 TeV. The exception is the significantly slower scaling exhibited by Phojet 1.12 which is however already in strong conflict with the LHC measurements, hence we do not consider it a realistic variation 1 .…”

Open issues in hadronic interactions for air showers

“…As shown in Fig. 6 (left-hand side) and in a more general way in [59], the average multiplicity is well reproduced by all the models up to 1 TeV and even up to 13 TeV for EPOS LHC and QGSJETII-04 [60] and a difference appears between these two models only at the highest energy (beyond 100 TeV). However, in the case of a nuclear target the slope of the rise of the multiplicity as function of the energy is different for all three models leading to a difference of about 20-30% at the highest energies in p or π -air interactions (Fig.…”

Review of Model Predictions for Extensive Air Showers

“…On the other hand the predictions from the models have larger differences for the multiplicity compared to the cross section. As shown in [46], the average multiplicity is well reproduced by all the models up to 1 TeV and even up to 13 TeV for EPOS LHC and QGSJETII-04 [47] and a difference appears between these two models only at the highest energy (beyond 100 TeV).…”