  Based on a newly proposed mirror-matter model of neutron-mirror neutron
($n-n'$) oscillations, the puzzles related to ultrahigh-energy cosmic rays
(UHECRs) are explained. In particular, the phenomena around the
Greisen-Zatsepin-Kuzmin (GZK) cutoff for UHECRs can be well understood under
the new mirror matter model assuming a mirror-to-ordinary temperature ratio of
$T'/T \sim 0.3$. The suppression factor of the GZK effect due to the opacity of
cosmic microwave background is calculated and agrees with the observations
well. Most of the super-GZK events (i.e., above the GZK cutoff), as predicted
in the new model, come from mirror matter sources that are invisible to
electromagnetic telescopes and can penetrate the mirror cosmic microwave
background at much further distances. Most remarkably, the anti-correlation
between super-GZK and sub-GZK events in the hotspot observed by the Telescope
Array (TA) collaboration can be naturally understood in this model. The
possible correlations between the UHECRs from the TA hotspot and other nearby
powerful sources such as high energy neutrinos detected by IceCube, the largest
black hole merger (GW170729) observed by LIGO, and the hottest star-forming
supercluster Lynx Arc, are discussed as well under the new theory.
