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Yuval Ne'eman


1962 International Conference at Geneva and the birth of quarks
Murray Gell-Mann Scientist
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In 1962, at the International Conference in Geneva, a… an excited psi particle was reported and I looked at the energies of the… the three-three resonance, which of course was now regarded as an excited particle, and the… an excited sigma. And there was the mass, newly reported mass of an excited psi, and the two mass intervals were equal. Well that suggested if the Eightfold Way scheme was correct, that we were dealing with a decimet. In the case of the decimet the two terms in the mass formula both gave the same result–so there was only one term really–and therefore a greater predictive power than for an octet. For an octet there was single linear relation among the masses of the, say the psi, sigma, lambda nucleon, but for the decimet, the prediction was stronger the spacing had to be equal. And the experimental result reported at the conference was that between the delta, as I called it–that is an i equal three halves… i equal three halves  version of the nucleon–between the delta and the sigma, and between the sigma and the psi there was the same spacing, so there ought to be a singlet, with a predictable mass, something like 1670, 1675 MeV.

We applied the formula to the masses themselves in the case of baryons, and to the mass squares in the case of bosons. Well, I got very excited and ran up to the front of the room and wrote something or other on the blackboard. But I was so excited that I had made a mistake: instead of saying that the prediction was of a… a negative particle of strangeness minus three, a singlet, an isotopic singlet, I said it was a neutral particle of strangeness minus three. And I corrected it of course after a while, but it just indicated how excited I was about it. And I indicated the decay schemes. It would have very conspicuous cascade, double cascade decays; decays into K-plus… -minus plus lambda, or into pi-minus plus psi-naught; pi-naught plus psi-minus also, but that would be less conspicuous. And at… immediately afterwards, I think it was at lunch, or at dinner, Nick Samios and Jack [sic] Leitner said that they wanted to search for this new predicted particle at Brookhaven using their bubble chamber research, and would I write a note to Maurice Goldhaber, the director of Brookhaven, suggesting that this is a good idea. So I scrawled a note on a napkin in the CERN cafeteria, or wherever it was we were meeting--I think it was, I'm not sure where we were meeting, CERN hadn't been fully established by then—anyway, I wrote a note on a napkin in the cafeteria and handed it to them. And I said the Eightfold Way scheme clearly predicted this particle with decays… indicated decays and it should be very conspicuous, and I suggested that they look for it. They were given permission to look for it and after scanning two million feet of film they finally found two examples within a few days of each other, one of each decay. One… one was an example of the decay into K-minus plus lambda; and the other was a… an… the first one was an example of pi-minus plus psi-naught, I believe. But that wasn't until, I think February 1st, 1964, the same day that the letter to the Physical Review about quarks appeared.

New York-born physicist Murray Gell-Mann (1929-2019) was known for his creation of the eightfold way, an ordering system for subatomic particles, comparable to the periodic table. His discovery of the omega-minus particle filled a gap in the system, brought the theory wide acceptance and led to Gell-Mann's winning the Nobel Prize in Physics in 1969.

Listeners: Geoffrey West

Geoffrey West is a Staff Member, Fellow, and Program Manager for High Energy Physics at Los Alamos National Laboratory. He is also a member of The Santa Fe Institute. He is a native of England and was educated at Cambridge University (B.A. 1961). He received his Ph.D. from Stanford University in 1966 followed by post-doctoral appointments at Cornell and Harvard Universities. He returned to Stanford as a faculty member in 1970. He left to build and lead the Theoretical High Energy Physics Group at Los Alamos. He has numerous scientific publications including the editing of three books. His primary interest has been in fundamental questions in Physics, especially those concerning the elementary particles and their interactions. His long-term fascination in general scaling phenomena grew out of his work on scaling in quantum chromodynamics and the unification of all forces of nature. In 1996 this evolved into the highly productive collaboration with James Brown and Brian Enquist on the origin of allometric scaling laws in biology and the development of realistic quantitative models that analyse the influence of size on the structural and functional design of organisms.

Tags: Geneva, Brookhaven National Laboratory, Physical Review, European Organization for Nuclear Research, Nick Samios, Jack Leitner, Maurice Goldharber

Duration: 5 minutes, 29 seconds

Date story recorded: October 1997

Date story went live: 24 January 2008