Ultrahigh-Energy Proton–Proton Interaction in the Laboratory Frame as a Source of Proton, Neutrinos, and Gamma-Ray Spectra in Astrophysics

Abstract

Similar spectral features are observed in the ultrahigh-energy cosmic-ray proton, neutrino, and gamma-ray spectra. The proton production spectra measured in proton–proton collisions at colliders exhibit structures whose prominence increases with collision energy. When the simulated accelerator spectrum is transformed from the center-of-mass frame to the laboratory frame, a feature analogous to the so-called knee appears at the position corresponding to the central rapidity region. At the high-energy end of the spectra, cosmic neutrinos and gamma rays, originating from the decays of secondary heavy hyperons and neutral pions, exhibit a humplike structure that is not expected within conventional models of cosmic proton acceleration. Assuming that primary protons are emitted from the source with already ultrahigh energies and that secondary particles are produced there through quark–gluon string fragmentation, it follows that the observed features in the proton, neutrino, and gamma-ray spectra may result from triple-Pomeron diffractive scattering. From the energy position of the knee in the proton spectrum, the initial proton energy near the cosmic source is estimated to be E₀ ~10¹² GeV.