Symmetries in particle physics
Symmetries in particle physics
Symmetries in particle physics
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<strong>Symmetries</strong><br />
Isosp<strong>in</strong> and G-parity<br />
Pions and isosp<strong>in</strong>: G-parity<br />
How does this work for the mesons (the pions) <br />
Pions = bound states of a quark and an antiquark,<br />
so naively: “Just add the isosp<strong>in</strong>s like the sp<strong>in</strong>s”.<br />
But: Rules of sp<strong>in</strong> addition not sufficient. How to<br />
“bar” a sp<strong>in</strong> Problem: want to preserve some<br />
symmetries like charge conjugation under “barr<strong>in</strong>g”.<br />
G-parity (a group-theory construct) demands:<br />
conserved quantum number <strong>in</strong> strong <strong>in</strong>teractions.