Pseudoscalar meson
= Pseudoscalar meson
{title2=$J^P=0^-$}
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A <meson> with zero <spin angular momentum> and negative <parity>. The <pion> and <kaon> are familiar examples. Between two <pseudoscalar mesons>, <parity conservation> in the strong interaction forces the <axial current> matrix element to vanish, while the <vector current> has <pseudoscalar-to-pseudoscalar form factors>. The weak decay as a whole need not conserve <parity>.