Editing Charm quark (section)

==== J/psi meson (1974) ====
{{Main|J/psi meson}}

In 1974, [[Samuel C. C. Ting]] was searching for charmed particles at [[Brookhaven National Laboratory]] (BNL).{{sfn|Riordan|1987|pp=[https://archive.org/details/huntingofquarktr00mich/page/297 297–298]}} His team was using an electron-pair detector.{{sfn|Ting|1977|p=239}} By the end of August, they found a peak at {{val|3.1|u=GeV/c2}} and the signal's width was less than {{val|5|u=MeV}}.{{sfn|Ting|1977|p=243}} The team was eventually convinced they had observed a massive particle and named it "J". Ting considered announcing his discovery in October 1974, but postponed the announcement due to his concern about the μ/π ratio.{{sfn|Ting|1977|p=244}}

At the [[Stanford Linear Accelerator Center]] (SLAC), [[Burton Richter]]'s team performed experiments on 9–10 November 1974. They also found a high probability of interaction at {{val|3.1|u=GeV/c2}}. They called the particle "psi".{{sfn|Southworth|1976|p=385}} On 11 November 1974, Richter met Ting at the SLAC,{{sfn|Southworth|1976|pp=385–386}} and they announced their discovery.{{sfn|Rosner|1998|p=16}}

Theorists immediately began to analyze the new particle.{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/300 300]}} It was shown to have a lifetime on the scale of 10<sup>−20</sup> seconds, suggesting special characteristics.{{sfn|Southworth|1976|p=385}}{{sfn|Riordan|1987|p=300}} [[Thomas Appelquist]] and [[David Politzer]] suggested that the particle was composed of a charm quark and a charm antiquark whose [[Spin (particle physics)|spins]] were aligned in parallel. The two called this configuration "charmonium".{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/300 300]}} Charmonium would have two forms: "orthocharmonium", where the spins of the two quarks are parallel, and "paracharmonium", where the spins align oppositely.{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/304 304]}} Murray Gell-Mann also believed in the idea of charmonium.{{sfn|Riordan|1987|loc = p. 300, "Murray&nbsp;... thinks that the charm–anticharm vector meson is more likely"}} Some other theorists, such as [[Richard Feynman]], initially thought the new particle consisted of an [[up quark]] with a charm antiquark.{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/300 300]}}

On 15 November 1974, Ting and Richter issued a press release about their discovery.{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/301 301]}} On 21 November at the SLAC, [[SPEAR]] found a resonance of the J/psi particle at {{val|3.7|u=GeV/c2}} as [[Martin Breidenbach]] and Terence Goldman had predicted.{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/301 301]}} This particle was called ψ′ ("psi-prime").{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/303 303]}} In late November, Appelquist and Politzer published their paper theorizing charmonium. Glashow and Alvaro De Rujula also published a paper called "Is Bound Charm Found?", in which they used the charm quark and [[asymptotic freedom]] to explain the properties of the J/psi meson.{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/305 305]}}

Eventually, on 2 December 1974, ''[[Physical Review Letters]]'' (PRL) published the discovery papers of J and psi, by Ting{{sfn|Aubert et al.|1974}} and Richter{{sfn|Augustin et al.|1974}} respectively.{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/305 305]}} The discovery of the psi-prime was published the following week.{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/305 305]}} Then, on 6 January 1975, ''PRL'' published nine theoretical papers on the J/psi particle; according to Michael Riordan, five of them "promoted the charm hypothesis and its variations".{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/306 306]}} In 1976, Ting and Richter shared the [[Nobel Prize in Physics]] for their discovery "of a heavy elementary particle of the new kind".{{sfn|Southworth|1976|p=383}}

In August 1976, in ''[[The New York Times]]'', Glashow recalled his wager and commented, "John [Iliopoulos]'s wine and my hat had been saved in the nick of time".{{sfn|Glashow|1976}} At the next EMS conference, spectroscopists ate Mexican candy hats supplied by the organizers.{{sfn|Riordan|1987|p=[https://archive.org/details/huntingofquarktr00mich/page/321 321]}}{{sfn|Rosner|1998|p=18}} [[Frank Close]] wrote a ''[[Nature (journal)|Nature]]'' article titled "Iliopoulos won his bet" in the same year, saying the 18th ICHEP was "indeed dominated by that very discovery".{{sfn|Close|1976|p=537}} No-one paid off their bets to Iliopoulos.{{sfn|Riordan|1987|pp=[https://archive.org/details/huntingofquarktr00mich/page/319 319–320]}}{{sfn|Rosner|1998|p=16}}