when the concept of asymptotic freedom was identified. However, a naive mixture of electroweak theory and the quark model led to calculations about known decay modes that contradicted observation: In particular, it predicted Z boson-mediated flavor-changing decays of a strange quark into a down quark, which were not observed. A 1970 idea of Sheldon Glashow, John Iliopoulos, and Luciano Maiani, known as the GIM mechanism, showed that the flavor-changing decays would be strongly suppressed if there were a fourth quark (now called the charm quark) that was a complementary counterpart to the strange quark. By summer 1974 this work had led to theoretical predictions of what a charm + anticharm meson would be like. The predictions were ignored. The work of Richter and Ting was done mostly to explore new energy regimes, not to test the theoretical predictions. The group at Brookhaven, were the first to discern a peak at 3.1 GeV in plots of production rates, first recognizing the ψ meson – that Ting named the "J" meson (after himself – his last-name written in Chinese is 丁 – or maybe not after himself). Decay modes Hadronic decay modes of are strongly suppressed because of the OZI rule. This effect strongly increases the lifetime of the particle and thereby gives it its very narrow decay width of just . Because of this strong suppression, electromagnetic decays begin to compete with hadronic decays. This is why the has a significant branching fraction to leptons. The primary decay modes are: melting In a hot QCD medium, when the temperature is raised well beyond the Hagedorn temperature, the and its excitations are expected to melt. This is one of the predicted signals of the formation of the quark–gluon plasma. 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 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 are produced and/or destroyed at time of QGP hadronization. Thus, there is uncertainty in the prevailing conditions at the initial collisions. In fact, instead of suppression, enhanced production of is expected in heavy ion experiments at LHC where the quark-combinant production mechanism should be dominant given the large abundance of charm