Introduction to QCD slides - P.Hoyer.pdf - High Energy Physics Group
Introduction to QCD slides - P.Hoyer.pdf - High Energy Physics Group
Introduction to QCD slides - P.Hoyer.pdf - High Energy Physics Group
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Paul <strong>Hoyer</strong> Mugla 2010<br />
The Pion as a carrier of the strong force<br />
In 1935 Hideki Yukawa suggested the existence of a new, strongly interacting<br />
particle “U” (later named the pion). The strength and range of the strong<br />
interaction could be unders<strong>to</strong>od as arising from pion exchange.<br />
• • •<br />
π<br />
• • •<br />
π<br />
π<br />
N<br />
• • •<br />
R < ∼ 1/Mπ<br />
Postulating a new particle was considered very bold in those days, when<br />
only a handful of elementary particles were known: pho<strong>to</strong>n, pro<strong>to</strong>n, neutron,<br />
electron, (neutrino).<br />
It has been suggested that “social pressure” may have kept physicists in the<br />
West from a similar proposal.<br />
Even <strong>to</strong>day in <strong>QCD</strong>, the pion is special: It is a Golds<strong>to</strong>ne boson.<br />
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