Cosmic-ray muons are generated from the decay of mesons which are secondary particles produced via hadronic interaction between primary cosmic-ray particles and atmospheric nuclei at the upper the atmosphere. The mesons such pions and kaons mostly decay into muons immediately, reflecting
the details of the hadronic interactions depending on their energy and lifetime. The modulation of the cosmic-ray muon rate as well as the flux and the atmospheric kaon-to-pion production ratio are important to determine the flux and energy of the atmospheric neutrino. In particular, the kaon-to-pion production ratio ๐K/ ๐ is measured with the correlation coefficient ๐ผT between the cosmic-ray muon rate in the underground detector and the atmospheric temperature. As a result, we obtained the correlation coefficient ๐ผ๐ = 0.85 ยฑ 0.01 (statistical uncertainty only) and ๐K/ ๐ = 0.12 ยฑ 0.03 (statistical uncertainty only) using the data taken in 10 years at the Super-Kamiokande detector. In this article, we report the current status of measurement of the modulation of the comic-ray muon and the atmospheric kaon-to-pion production ratio.
