J/psi meson

The importance of this discovery[citation needed] is highlighted by the fact that the subsequent, rapid changes in high-energy physics at the time have become collectively known as the "November Revolution".

Despite the ability of quark models to bring order to the "elementary particle zoo", they were considered something like mathematical fiction at the time, a simple artifact of deeper physical reasons.

[3] Starting in 1969, deep inelastic scattering experiments at SLAC revealed surprising experimental evidence for particles inside of protons.

On the theoretical front, gauge theories with broken symmetry became the first fully viable contenders for explaining the weak interaction after Gerardus 't Hooft discovered in 1971 how to calculate with them beyond tree level.

Gauge theories with quarks became a viable contender for the strong interaction in 1973, when the concept of asymptotic freedom was identified.

The group at Brookhaven,[a] were the first to discern a peak at 3.1 GeV in plots of production rates and named the particle the ψ meson.

Heavy-ion experiments at CERN's Super Proton Synchrotron and at BNL's Relativistic Heavy Ion Collider have studied this phenomenon without a conclusive outcome as of 2009.

This is due to the requirement that the disappearance of J/ψ mesons is evaluated with respect to the baseline provided by the total production of all charm quark-containing subatomic particles, and because it is widely expected that some J/ψ are produced and/or destroyed at time of QGP hadronization.

Aside of J/ψ, charmed B mesons (Bc), offer a signature that indicates that quarks move freely and bind at-will when combining to form hadrons.

[4] Much of the scientific community considered it unjust to give one of the two discoverers priority, so most subsequent publications have referred to the particle as the "J/ψ".