Particle Physics Contributions

Haim Harari's first scientific paper was published at the age of 21. He received his Ph.D. in Israel in 1965 and became one of the first postdoctoral fellows in the newly established Stanford Linear Accelerator Center (SLAC), Stanford University.


In 1967, at the age of 26, Harari was appointed a tenured Associate Professor at the Weizmann Institute. He was and still is, the youngest Professor ever appointed at the Institute. He was promoted to Full Professor three years later, as the Annenberg Professor of High Energy Physics.


Harari’s contributions to Particle Physics are all in the area of the phenomenology and theory of particle interactions. He contributed mainly to five sub-fields, changing focus approximately every five years.


The first field (1962-1967) was symmetries of particle interactions, at a time when SU(3), SU(6) and other symmetries were being developed.


The second field (1968-1973) was “Duality” in Strong Interaction Physics and its connection to models for particle scattering. He published two of the first fundamental papers on duality, one about the role of Diffraction Scattering in Duality and the other, inventing the “Duality Diagrams”, and establishing, for the first time, a connection between duality and the quark hypothesis. The early work on duality led others later to the first ideas of string theory. He became a leading authority on phenomenological topics, such as photo-production, resonance models and hadronic processes and was invited to deliver one of the central summary talks in the main International Particle Physics Conference in every one of the years 1967, 1968, 1969 and 1971, and to deliver the Loeb Lectures at Harvard in 1970.


The third field (1974-1979) followed the experimental discovery of “hidden charm” in November 1974, when he became one of the leaders in the field of the new quarks and leptons. He was the first to propose a model of six quarks and six leptons, naming the two new quarks “top” and “bottom” (names presently accepted by all) and predicting the existence of six leptons. In August 1975, at the Stanford International Particle Physics conference he presented, for the first time ever, the full synthesis accepted today as “the standard model” of six quarks and six leptons. The term “(three) generations of quarks and leptons,” commonly used for describing the pattern of quarks and leptons in the standard model, was coined by Harari and was first introduced by him in 1976 at the Weak and Electromagnetic Interactions at High Energy, Les Houches Su​​mmer School and in 1977 at the 5th International Conference on Experimental Meson Spectroscopy, Boston. Between 1975 and 1988 he was invited to speak on these topics in many dozens of conferences and summer-schools, to deliver distinguished named lectures in UC Berkeley, Stanford, Carnegie-Mellon, Hebrew University and the Israel Academy, and numerous other talks. ​


The fourth field (1979-1985) was started with a simple model, according to which all quarks and leptons consist of various combinations of only two fundamental building blocks of matter, named “Rishons”. The model is striking in its simplicity, explains the systematic pattern but cannot explain the dynamics of creating the composite quarks and leptons. A later version of the model, published with then-graduate student Nathan Seiberg, proposed a dynamical model for the same idea, and additional papers elaborated on it. To date, there is no evidence for quark and lepton compositeness and most theoretical attempts proceed in entirely different directions. There is also no evidence against compositeness and no successful alternative explanation for the observed patterns. The "Rishons", if they exist, may play a role in the processes of the early universe, including the genesis of the Baryon number of the universe (matter-antimatter asymmetry) and the cosmological dark matter puzzle.


The fifth field (1985-1989) has been Neutrino Physics and its implications for astrophysics, cosmology and particle physics. Since becoming President of the Weizmann Institute, he has not been engaged in active research, although he kept an active interest and lectured often on topics in Neutrino Physics and on the speculation that an additional level of sub-particles exists.


Harari published more than 120 papers on particle physics in the leading international journals. He was elected to the Israel Academy of Sciences (1978) and the American Academy of Arts and Science (2010) and was awarded the Weizmann Prize (1973), the Rothschild Prize (1976) and the Israel Prize (1989). In 1999 he was appointed “Institute Professor” at the Weizmann Institute.