On the discovery of the Greisen-Zatzepin-Kuzmin cut-off

摘要

The recent claim of the ‘5 sigma’ observation of the Greisen-Zatzepin-Kuzmin cut-off by the HiRes group based on their nine years data is a significant step towards the eventual solution of one of the most intriguing questions in physics for more than 40 years. Recent results from Pierre Auger Observatory seem to confirm the statement. However, the word ‘significance’ is used in the mentioned paper in a sense which is not quite obvious. In the present paper we argue that this claim is a little premature.