Originally known as a V particle due to its decay pattern, its tendency to decay into either two or three pions led to the Tau-Theta puzzle.
Along with an electron, this particle is the product of the semileptonic decay of a D meson. Gell-Mann and Pais investigated the oscillations in its neutral type, noticing that a pure beam would become a beam of its anti-particle. Leon Lederman established that it had two different weak eigenstates, which are labeled "short" and "long." Its (*) charged type contains an up quark and is 4-mega-electron volts lighter than its neutral type, which contains a down quark. Originally known as a V particle due to its decay pattern, its tendency to decay into either two or three pions led to the Tau-Theta puzzle. FTP, name this meson which is heavier than a pion and contains a strange quark or antiquark.
Along with an electron, this particle is the product of the semileptonic decay of a D meson.
kaon or K-meson (accept k-zero until the asterisk)