Extended Air Shower Simulations Based on EPOS

We discuss air shower simulations based on the EPOS hadronic interaction model. A remarkable feature is the fact that the number of produced muons is considerably larger compared to other interaction models. We show that this is due to an improved treatment of baryon-antibaryon production.Comment: Talk presented at EDS0

Global properties of proton-proton collisions at s\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 $\sigma_{\rm inel}$ = 105 $\pm$ 2 mb; (ii) total charged multiplicity $\rm N_{_{\rm ch}}$ = 150 $\pm$ 20; (iii) charged particle pseudorapidity density at midrapidity $\rm dN_{ch}/d\eta|_{\eta=0} = 9.6 \pm 0.2$; (iv) energy density at midrapidity $\rm dE/d\eta|_{\eta=0} = 13.6 \pm 1.5$ 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 $\rm = 0.76 \pm 0.07$ GeV/c. At midrapidity, EPOS and QGSJET-II predict larger per-event multiplicity probabilities at very low ($\rm N_{\rm ch}100$) 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.Comment: 10 pages, 11 figures. Minor changes. Matches version published in JHE

Impact of QCD jets and heavy-quark production in cosmic-ray proton atmospheric showers up to 1020^{20} eV

The PYTHIA 6 Monte Carlo (MC) event generator, commonly used in collider physics, is interfaced for the first time with a fast transport simulation of a hydrogen atmosphere, with the same density as air, in order to study the properties of extended atmospheric showers (EAS) produced by cosmic ray protons with energies E$_{CR}\approx 10^{14}$--$10^{20}$ eV. At variance with the hadronic MC generators (EPOS-LHC, QGSJET, and SIBYLL) commonly used in cosmic-rays physics, PYTHIA includes the generation of harder hadronic jets and heavy (charm and bottom) quarks, thereby producing higher transverse momentum final particles, that could explain several anomalies observed in the data. The electromagnetic, hadronic, and muonic properties of EAS generated with various settings of PYTHIA 6, tuned to proton-proton data measured at the LHC, are compared to those from EPOS-LHC, QGSJET 01, QGSJET II, and SIBYLL 2.1. Despite their different underlying parton dynamics, the characteristics of the EAS generated with PYTHIA 6 are in between those predicted by the rest of MC generators. The only exceptions are the muonic components at large transverse distances from the shower axis, where PYTHIA predicts more activity than the rest of the models. Heavy-quark production, as implemented in this study for a hydrogen atmosphere, does not seem to play a key role in the EAS muon properties, pointing to nuclear effects as responsible of the muon anomalies observed in the air-shower data.Comment: 13 pages, 20 figure

Particle Production in Proton-Proton and Deuteron-Gold Collisions at RHIC

We try to understand recent data on proton-proton and deuteron-gold collisions at RHIC, employing a parton model approach called EPOS.Comment: Invited talk, given at SQM2004, Cape Town, South Africa, 15-20 September, 200

Collective flow in (anti)proton-proton collision at Tevatron and LHC

Collective flow as a consequence of hydrodynamical evolution in heavy ion collisions is intensively studied by theorists and experimentalists to understand the behavior of hot quark matter. Due to their large mass, heavy ions suffer collective effects even at low (SPS) or intermediate energies (RHIC). In case of light systems such as (anti)proton-proton interactions, collective effects was not expected. Within a global model such as EPOS, where light and heavy systems are treated using the same physics, it appears that Tevatron data are better described if a flow is introduced. Then the extrapolation to LHC can easily be done and we can compare to first data from ATLAS experiment.Comment: 4 pages, 6 figures, Proceeding of the 45th Rencontres de Moriond QC

Parton Ladder Splitting and the Rapidity Dependence of Transverse Momentum Spectra in Deuteron-Gold Collisions at RHIC

We present a phenomenological approach (EPOS), based on the parton model, but going much beyond, and try to understand proton-proton and deuteron-gold collisions, in particular the transverse momentum results from all the four RHIC experiments. It turns out that elastic and inelastic parton ladder splitting is the key issue. Elastic splitting is in fact related to screening and saturation, but much more important is the inelastic contribution, being crucial to understand the data. We investigate in detail the rapidity dependence of nuclear effects, which is actually relatively weak in the model, in perfect agreement with the data, if the latter ones are interpreted correctly.Comment: 39 pages, 28 figure

Hadronic Interactions and Air Showers: Where Do We Stand?

The interpretation of EAS measurements strongly depends on detailed air shower simulations. CORSIKA is one of the most commonly used air shower Monte Carlo programs. The main source of uncertainty in the prediction of shower observables for different primary particles and energies is currently dominated by differences between hadronic interaction models even after recent updates taking into account the first LHC data. As a matter of fact the model predictions converged but at the same time more precise air shower and LHC measurements introduced new constraints. Last year a new generation of hadronic interaction models was released in CORSIKA. Sibyll 2.3c and DPMJETIII.17-1 are now available with improved descriptions of particle production and in particular the production of charmed particles. The impact of these hadronic interaction models on air shower predictions are presented here and compared to the first generation of post-LHC models, EPOS LHC and QGSJETII-04. The performance of the new models on standard air shower observables is derived. Due to the various approaches in the physics treatment, there are still large differences in the model predictions but this can already be partially resolved by comparison with the latest LHC data