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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| J/psi meson | 2/2 | https://en.wikipedia.org/wiki/J/psi_meson | reference | science, encyclopedia | 2026-05-05T16:29:30.468827+00:00 | kb-cron |
== Name == Because of the nearly simultaneous discovery, the J/ψ is the only particle to have a two-letter name. Richter named it "SP", after the SPEAR accelerator used at SLAC; however, none of his coworkers liked that name. After consulting with Greek-born Leo Resvanis to see which Greek letters were still available, and rejecting "iota" because its name implies insignificance, Richter chose "psi" – a name which, as Gerson Goldhaber pointed out, contains the original name "SP", but in reverse order. Coincidentally, later spark chamber pictures often resembled the psi shape. Ting assigned the name "J" to it, saying that the more stable particles, such as the W and Z bosons had Roman names, as opposed to classical particles, which had Greek names. He also cited the symbol for electromagnetic current
j
μ
(
x
)
{\displaystyle j_{\mu }(x)}
which much of their previous work was concentrated on to be one of the reasons. 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". The first excited state of the J/ψ was called the ψ′; it is now called the ψ(2S), indicating its quantum state. The next excited state was called the ψ″; it is now called ψ(3770), indicating mass in MeV/c2. Other vector charm–anticharm states are denoted similarly with ψ and the quantum state (if known) or the mass. The "J" is not used, since Richter's group alone first found excited states. The name charmonium is used for the J/ψ and other charm–anticharm bound states. This is by analogy with positronium, which also consists of a particle and its antiparticle (an electron and positron in the case of positronium).
== See also == OZI rule List of multiple discoveries
== Footnotes ==
== References ==
== Sources == Glashow, S. L.; Iliopoulos, J.; Maiani, L. (1970). "Weak Interactions with Lepton–Hadron Symmetry". Physical Review D. 2 (7): 1285–1292. Bibcode:1970PhRvD...2.1285G. doi:10.1103/PhysRevD.2.1285. Aubert, J.; et al. (1974). "Experimental Observation of a Heavy Particle J". Physical Review Letters. 33 (23): 1404–1406. Bibcode:1974PhRvL..33.1404A. doi:10.1103/PhysRevLett.33.1404. Augustin, J.; et al. (1974). "Discovery of a Narrow Resonance in e+e− Annihilation". Physical Review Letters. 33 (23): 1406–1408. Bibcode:1974PhRvL..33.1406A. doi:10.1103/PhysRevLett.33.1406. Bobra, M. (2005). "Logbook: J/ψ particle". Symmetry Magazine. 2 (7): 34. Yao, W.-M.; et al. (Particle Data Group) (2006). "Review of Particle Physics: Naming Scheme for Hadrons" (PDF). Journal of Physics G. 33 (1): 108. arXiv:astro-ph/0601168. Bibcode:2006JPhG...33....1Y. doi:10.1088/0954-3899/33/1/001.