Measurement of Downward-going Milli-charged particles beyond GZK cutoff at the Pierre Auger Observatory

Fuente: arXiv
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Autor principal: Xu, Ye
Formato: Preprint
Publicado: 2025
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author Xu, Ye
author_facet Xu, Ye
contents It is assumed that superheavy dark matter particles (SHDM, $ϕ$) with $\mathcal{O}$(ZeV) mass may decay to relativistic milli-charged particles (MCPs, $χ$) via a channel $ϕ\toχ\barχ$ or $γχ\barχ$. The downward-going MCPs passing through the atmosphere can be measured by the Pierre Auger observatory (Auger). The massless hidden photon model is taken for MCPs to interact with nuclei, so that we evaluated the numbers and fluxes of expected MCPs at Auger assuming 14 years of Auger data. The hybrid data of Auger was fitted with the flux of UHE MCPs exceeding GZK-cutoff energy. Then the corresponding upper limits on $ε^2$ are calculated at 90\% C. L.. These results indicate that MCPs can be directly detected with $ε^2\gtrsim 2\times10^{-6}$ at Auger, when $m_ϕ=2\times10^{21}$ eV and $τ_ϕ=10^{27}$ s. And a new region of 10$^{9.6}$ < $m_{MCP}$ < 10$^{11.6}$ eV and $ε$ > $2.12\times10^{-2}$ is ruled out in the $m_{MCP}$-$ε$ plane with 14 years of Auger data. These results indicate potential existence of MCPs and SHDM in the Universe.
format Preprint
id arxiv_https___arxiv_org_abs_2506_07395
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Measurement of Downward-going Milli-charged particles beyond GZK cutoff at the Pierre Auger Observatory
Xu, Ye
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
It is assumed that superheavy dark matter particles (SHDM, $ϕ$) with $\mathcal{O}$(ZeV) mass may decay to relativistic milli-charged particles (MCPs, $χ$) via a channel $ϕ\toχ\barχ$ or $γχ\barχ$. The downward-going MCPs passing through the atmosphere can be measured by the Pierre Auger observatory (Auger). The massless hidden photon model is taken for MCPs to interact with nuclei, so that we evaluated the numbers and fluxes of expected MCPs at Auger assuming 14 years of Auger data. The hybrid data of Auger was fitted with the flux of UHE MCPs exceeding GZK-cutoff energy. Then the corresponding upper limits on $ε^2$ are calculated at 90\% C. L.. These results indicate that MCPs can be directly detected with $ε^2\gtrsim 2\times10^{-6}$ at Auger, when $m_ϕ=2\times10^{21}$ eV and $τ_ϕ=10^{27}$ s. And a new region of 10$^{9.6}$ < $m_{MCP}$ < 10$^{11.6}$ eV and $ε$ > $2.12\times10^{-2}$ is ruled out in the $m_{MCP}$-$ε$ plane with 14 years of Auger data. These results indicate potential existence of MCPs and SHDM in the Universe.
title Measurement of Downward-going Milli-charged particles beyond GZK cutoff at the Pierre Auger Observatory
topic High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2506.07395