Proton structure, high energy neutrinos, and dark matter searches
Astrophysics and Astronomy
Final Report Abstract
Accurate description of particle production in hadronic collisions is of extreme importance for experimental studies of ultra-high energy cosmic rays and high energy neutrinos, as well as to searches for dark matter signals. Among the main research activities pursued in the framework of the project has been a further development of the QGSJET-II and QGSJET-III Monte Carlo generators, aimed on improving the treatment of both high and low energy hadron-proton, hadron-nucleus, and nucleus-nucleus collisions, notably, concerning forward hadron production, for potential applications to various problems of high energy astrophysics. In particular, a significant research effort has been devoted to modeling of the nonperturbative structure of the proton, based on the “color fluctuations” approach; the corresponding formalism has been implemented in the QGSJET-II model. On the other hand, the phenomenological treatment of nonlinear interaction effects in the QGSJET-III model has been further developed, considering higher twist corrections to parton production processes, related to coherent multiple rescattering of s-channel partons. Based on a dedicated analysis of measured characteristics of extensive air showers induced by ultra-high energy cosmic rays, it has been shown that a coherent interpretation of those data, in terms of the primary cosmic ray composition, is not possible, unless one addresses systematic issues in the current experimental procedures. In relation to direct studies of charged cosmic rays, the impact of the isospin symmetry on near-threshold antinucleon production in proton-proton collisions has been studied. It has been demonstrated that the suppression of baryon resonance yields, close to the production threshold, gives rise to an almost a factor of two enhancement of the antineutron yield, compared to the one of antiprotons, and that such an enhancement quickly fades away with increasing energy. A new treatment for the production of light antinuclei in different reactions has been developed, combining a Monte Carlo description of the interactions with a semiclassical treatment of the coalescence process, based on Wigner function representations for produced antinuclei. The developed formalism has been applied for calculations of antinuclei signals of dark matter annihilations and of the fluxes of antinuclei produced by cosmic ray interactions with the interstellar medium, using the QGSJET-II model for the treatment of hadronic collisions and employing a two-zone diffusion model for the description of cosmic ray propagation in the Galaxy. In particular, the part of the energy spectrum of antinuclei, which is potentially interesting for experimental studies, due to an access of the respective dark matter signals over the backgrounds, has been identified.
Publications
- AAfrag: Interpolation routines for Monte Carlo results on secondary production in proton-proton, proton-nucleus and nucleus-nucleus interactions, Computer Physics Communications 245, 106846 (2019)
M. Kachelrieß, I. V. Moskalenko, and S. Ostapchenko
(See online at https://doi.org/10.1016/j.cpc.2019.08.001) - High energy interactions of cosmic rays, Advances in Space Research 64, 2445 (2019)
S. Ostapchenko
(See online at https://doi.org/10.1016/j.asr.2019.05.050) - Taming the Energy Rise of the Total Proton-Proton Cross-Section, Universe 5, 106 (2019)
S. Ostapchenko and M. Bleicher
(See online at https://doi.org/10.3390/universe5050106) - Alternative coalescence model for deuteron, tritium, helium-3 and their antinuclei, European Physical Journal A 56, 4 (2020)
M. Kachelrieß, S. Ostapchenko, and J. Tjemsland
(See online at https://doi.org/10.1140/epja/s10050-019-00007-9) - ELMAG 3.01: A three-dimensional Monte Carlo simulation of electromagnetic cascades on the extragalactic background light and in magnetic fields, Computer Physics Communications, 107163 (2020)
M. Blytt, M. Kachelrieß, and S. Ostapchenko
(See online at https://doi.org/10.1016/j.cpc.2020.107163)
