High-density QCD and Cosmic Ray Air Showers

Abstract

We discuss particle production in the high-energy, small-x limit of QCD where the gluon density of hadrons is expected to become nonperturbatively large. Strong modifications of the phase-space distribution of produced particles as compared to leading-twist models are predicted which reflect in the properties of cosmic ray induced air showers in the atmosphere. Assuming hadronic primaries, our results suggest a light composition near GZK cutoff energies. We also show that cosmic ray data discriminate among various QCD evolution scenarios for the rate of increase of the gluon density at small x, such as fixed-coupling and running-coupling BFKL evolution. There are clear indications for a slower growth of the gluon density as compared to RHIC and HERA, due e.g. to running-coupling effects.

arXiv comment5 pages, 1 figure

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Cited by in corpus (14)

• The Color Glass Condensate
• The Color Glass Condensate and hadron production in the forward region
• The Large Hadron-Electron Collider at the HL-LHC
• Hadronic Multiparticle Production at Ultra-High Energies and Extensive Air Showers
• Small-x Physics: From HERA to LHC and beyond
• Remnant Break-up and Muon Production in Cosmic Ray Air Showers
• Lecture notes on high energy cosmic rays
• Constraining high energy interaction mechanisms by studying forward hadron production at the LHC
• Percolation Effects in Very High Energy Cosmic Rays
• Impact of Uncertainties in Hadron Production on Air-Shower Predictions
• Forward Hadron Productions in high energy pp collisions from a Monte-Carlo generator for Color Glass Condensate
• Strong interactions in air showers
• High Energy Cosmic Ray Air Showers and small-x QCD
• The QCD Black Disk Limit in Cosmic Ray Air Showers