Various models were proposed to explain the observed spectrum and composition of ultra-high-energy cosmic rays (UHECRs), but they remain inconclusive in constraining their source of origin. A significant neutrino event with an estimated energy between 72 PeV and 2.6 EeV was recently observed by the KM3NeT experiment (KM3-230213A). When interpreted as cosmogenic in origin, this event can provide constraints on several phenomenological parameters of UHECR sources. In this contribution, we aim to constrain a two-population model of UHECRs using the cosmic-ray data of the Pierre Auger Observatory and multi-messenger constraints. The first population is mixed in composition, while the second population is comprised of ultra-high-energy (UHE) protons with a higher maximum rigidity. We present the best-fit solution to the spectrum and composition of UHECRs that is consistent with the detection of a single neutrino event by the KM3NeT detector at the energy range of KM3-230213A.
A. R. Alhebsi (Tue,) studied this question.