Measurement of the charge ratio and polarization of cosmic-ray muon using the tagged decay-e events in Super-Kamiokande

Neutrinos and muons from cosmic-ray interactions in the atmosphere originate from mesons, such as pions and kaons, in air-showers. An accuracy of the absolute atmospheric neutrino flux and its flavor ratio are limited due to the uncertainty of meson productions in hadronic interaction models. In order to reduce such uncertainty, measurements of the charge ratio and the polarization of cosmic-ray muons are important as new inputs to theoretical models which simulate the atmospheric neutrino flux. In this proceedings, we present the results of the charge ratio (R) and polarization (P^μ0) of cosmic-ray muon measurements using the decay electrons collected from 2008 September to 2022 June by the Super-Kamiokande (SK) detector. We measured muon charge ratio to be R = 1.32±0.02 (stat.+syst.) and the muon polarization at the production location to be P^μ0 = 0.52±0.01 (stat.+syst.). The SK detector uniquely measured the polarization of cosmic-ray muons with energies more than 1 TeV at sea-level because of its underground location.

Duke Scholars

Author Christopher Walter Physics

Author Kate Scholberg Physics