High Energy Hadronic Interactions and the Puzzles of the Cosmic Radiation

• Applicant: Sergey Ostapchenko, Ph.D.
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields ; Astrophysics and Astronomy
• Term: from 2021 to 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 465275045

• Final Report Year: 2025

Final Report Abstract

The principal goals of the project have been to apply novel theoretical approaches regarding the treatment of various aspects of high energy interactions to a number of challenging problems of high energy astrophysics, related to investigations of ultrahigh energy cosmic rays, measurements of high energy neutrino fluxes, and searches for extraterrestrial fluxes of antinuclei. In the framework of the project, the development of the QGSJET-III Monte Carlo (MC) generator of high energy hadronic collisions has been finalized, including a treatment of “color fluctuations” in interacting hadrons, of higher twist corrections to hard parton scattering processes, and of the pion exchange process. The MC generator has been applied to modeling of the development of extensive air showers (EAS) initiated by ultrahigh energy cosmic rays and a general quantitative analysis of model uncertainties for EAS predictions has been performed, within the standard physics picture and within the limits allowed by available accelerator data. The obtained uncertainties proved to be relatively small: up to 10% for EAS muon content and up to ≃ 10 g/cm2 for the EAS maximum depth, thereby indicating that model predictions for basic EAS characteristics are substantially constrained by accelerator data. The second part of the project has been devoted to a treatment of charmed hadron production in hadronic collisions, in relation to calculations of the atmospheric neutrino background. In particular, it has been demonstrated that the perturbative contribution to the prompt neutrino flux can be conveniently studied at the level of charm quark production, both regarding the respective theoretical uncertainties and for specifying the kinematic regions relevant for the corresponding calculations. Further, it has been demonstrated that the potential contribution to the prompt neutrino flux, arising from the nonperturbative intrinsic charm content of the proton, is substantially constrained by the data of the IceCube Observatory: with the allowed intrinsic charm being at the level of one per mille, i.e., one order of magnitude lower than previous estimations. A treatment of charmed hadron production in the framework of the QGSJET-III MC generator has been developed, including both the leading order perturbative description for charm (anti)quark production and a phenomenological modeling of the nonperturbative intrinsic charm content of hadrons. A further development of the treatment of the production of light antinuclei in small interacting systems has been performed, including a generalization of the corresponding approach, for going beyond the equal-time approximation. The corresponding production cross sections have been calculated for different reactions and for a wide energy range relevant for astrophysical studies and made publicly available.

Publications

• Energy spectra of secondaries in proton-proton interactions. Physical Review D, 104(12).
  Koldobskiy, S.; Kachelrieß, M.; Lskavyan, A.; Neronov, A.; Ostapchenko, S. & Semikoz, D. V.
  
• QGSJET-III Model: Novel Features. Physics of Atomic Nuclei, 84(6), 1017-1025.
  Ostapchenko, S.
  
• AAfrag 2.01: interpolation routines for Monte Carlo results on secondary production including light antinuclei in hadronic interactions. Computer Physics Communications, 287, 108698.
  Kachelrieß, M.; Ostapchenko, S. & Tjemsland, J.
  
• Cosmic ray interactions in the atmosphere: QGSJET-III and other models. SciPost Physics Proceedings(13).
  Ostapchenko, Sergey
  
• Effect of nonequal emission times and space-time correlations on (anti-) nuclei production. Physical Review C, 108(2).
  Kachelrieß, M.; Ostapchenko, S. & Tjemsland, J.
  
• On the prompt contribution to the atmospheric neutrino flux. Physical Review D, 107(2).
  Ostapchenko, Sergey; Garzelli, Maria Vittoria & Sigl, Günter
  
• Model uncertainties for the predicted maximum depth of extensive air showers. Physical Review D, 110(6).
  Ostapchenko, Sergey & Sigl, Günter
  
• On the model uncertainties for the predicted muon content of extensive air showers. Astroparticle Physics, 163, 103004.
  Ostapchenko, Sergey & Sigl, Günter
  
• QGSJET-III model of high energy hadronic interactions. II. Particle production and extensive air shower characteristics. Physical Review D, 109(9).
  Ostapchenko, Sergey
  
• QGSJET-III model of high energy hadronic interactions: The formalism. Physical Review D, 109(3).
  Ostapchenko, Sergey