Charm quarks were produced almost simultaneously by two teams in November 1974 (see November Revolution) – one at SLAC under Burton Richter, and one at Brookhaven National Laboratory under Samuel Ting. The charm quarks were observed bound with charm antiquarks in mesons. The two parties had assigned the discovered meson two different symbols, J and ψ; thus, it became formally known as the J/ψ meson. The discovery finally convinced the physics community of the quark model's validity.[35]
In the following years a number of suggestions appeared for extending the quark model to six quarks. Of these, the 1975 paper by Haim Harari[41] was the first to coin the terms top and bottom for the additional quarks.[42]
In 1977, the bottom quark was observed by a team at Fermilab led by Leon Lederman.[43][44] This was a strong indicator of the top quark's existence: without the top quark, the bottom quark would have been without a partner. It was not until 1995 that the top quark was finally observed, also by the CDF[45] and DØ[46] teams at Fermilab.[5] It had a mass much larger than expected,[47] almost as large as that of a gold atom.[48]
No comments:
Post a Comment