Kaons and Hyperons

New particles called kaons were discovered, about 3.5 times as massive as a pion but still only half as massive as a proton or neutron and was called a K-meson, which was sometimes abbreviated to kaon. Additional newly discovered particles heavier than kaons were termed hyperons.
 Marian Danysz, Jerzy Pniewski Poland 1952 Kaons and Hyperons

New particles called kaons were discovered, about 3.5 times as massive as a pion but still only half as massive as a proton or neutron and was called a K-meson, which was sometimes abbreviated to kaon. Additional newly discovered particles heavier than kaons were termed hyperons.