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23 - From the S-matrix to string theory
- from Part IV - The string
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- By Yoichiro Nambu, University of Chicago
- Edited by Andrea Cappelli, Elena Castellani, Università degli Studi di Firenze, Italy, Filippo Colomo, Paolo Di Vecchia
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- Book:
- The Birth of String Theory
- Published online:
- 05 May 2012
- Print publication:
- 12 April 2012, pp 275-282
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Summary
String theory traces its origin to the Veneziano model of 1968. It also happens that the Weinberg–Salam model was born about the same time. The latter has led to the successful Standard Model. The descendants of the former, on the other hand, are still struggling to be relevant to the real world in spite of their enormous theoretical appeal. Indeed there exist two pathways in the development of theoretical particle physics since its beginnings in the Thirties. I will call them the quantum field theory and the S-matrix theory respectively. In its historical lineage, the Standard Model belongs to the former, whereas the superstring theory belongs to the latter. Even though the former has turned out to be the Royal Road of particle physics, this was not entirely clear before its final triumph, and the latter has also played very important contributing roles which continue to this day. The purpose of this note is to follow this other pathway and discuss the topics that have influenced my thoughts.
In the Thirties, when nuclear physics was developing, there were uncertainties in the minds of physicists about the efficacy of quantum field theory which was still in its early stages of development. For one thing, quantum field theory had inherited the self-energy difficulty from classical theory although the degree of divergence was found to be milder. For another, the unknown nature of nuclear forces and the much higher energy range involved than in atomic phenomena made people suspect that quantum mechanics might fail in dealing with nuclear phenomena, just as the classical theory failed with atomic phenomena.
28 - Panel Session: Spontaneous Breaking of Symmetry
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- By Laurie M. Brown, Born Brooklyn, New York, 1923; Ph.D., 1951 (physics), Cornell University; Professor Emeritus of Physics and Astronomy at Northwestern University; high-energy physics (theory) and history of physics., Robert Brout, Born New York City, 1928; Ph.D., 1953 (physics), Columbia University; Professor of Physics at the Université Libre de Bruxelles; statistical mechanics and high-energy physics (theory)., Tian Yu Cao, Born Shanghai, China, 1941; Ph.D., 1987 (history and philosophy of science), University of Cambridge; Assistant Professor of Philosophy, Boston University; history and philosophy of science., Peter Higgs, Born Newcastle-upon-Tyne, United Kingdom, 1929; Ph.D., 1954 (physics), King's College, London; Professor of Theoretical Physics at the University of Edinburgh; high-energy physics (theory)., Yoichiro Nambu, Born Tokyo, Japan, 1921; Sc.D., 1952 (theoretical physics), University of Tokyo; Professor Emeritus of Physics, Enrico Fermi Institute, University of Chicago; high-energy physics (theory).
- Edited by Lillian Hoddeson, University of Illinois, Urbana-Champaign, Laurie Brown, Northwestern University, Illinois, Michael Riordan, Stanford University, California, Max Dresden, Stanford University, California
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- Book:
- The Rise of the Standard Model
- Published online:
- 03 February 2010
- Print publication:
- 13 November 1997, pp 478-522
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Summary
This panel was intended to function as a discussion, but instead it emerged as a series of short presentations by the participants Robert Brout, Tian Yu Cao, and Peter Higgs, with an introductory discussion by the chair. The present chapter consists of a revised and edited version of those reports and also includes a later submission by Yoichiro Nambu, who was scheduled to be on the panel originally but was unable to attend.
Introduction
The two sectors of the current Standard Model of particle physics, the strong color and the electroweak sectors, are distinct and are tied together only by ontology. Together, they describe the interactions, other than gravitation, of the three generations of quarks and leptons. The dream of representing the strong and weak “nuclear” interactions (as they were known before the acceptance of the quarks) as quantum field theories (QFT) goes back to the 1930s. The first such QFT, other than quantum electrodynamics, was Enrico Fermi's weak-interaction theory of 1934. This theory was almost immediately extended by Werner Heisenberg in 1935 to include the strong interactions (thus making it the first unified QFT) whose exchanged “quanta” were those of the electron-neutrino “Fermi-field.” In 1935, Hideki Yukawa invented “U-quanta,” now called pions, to represent the field of strong interactions, adjusting their mass to fit the range of nuclear forces. This was again a unified QFT, as the U-quanta were also intended to serve as intermediate bosons of the weak interaction.
44 - Gauge principle, vector-meson dominance, and spontaneous symmetry breaking
- Edited by Laurie Mark Brown, Max Dresden, Lillian Hoddeson
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- Book:
- Pions to Quarks
- Published online:
- 07 May 2010
- Print publication:
- 24 November 1989, pp 639-642
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Summary
With the benefit of hindsight, I would like to speak on certain theoretical developments that occurred during the late 1950s. The subject matter I shall discuss centers around the views regarding the meaning and role of symmetries, or the lack thereof. I shall talk in particular about the happenings in Chicago, not only because they are what I experienced at first hand but also because one of the participants, Jun John Sakurai, unfortunately cannot be heard any more. Let me begin by stating that, at the risk of oversimplification, I regard Ernest Lawrence and Hideki Yukawa as the two founding fathers of particle physics, in that they respectively established the basic experimental and theoretical methodologies in this field. That these are the basic methodologies still holds true, with some qualifications that I shall come to in a moment.
Limiting myself to the theoretical side only, Yukawa's way was to freely invent (or postulate) new particles in order to explain phenomena that are new or not yet understood. Although Yukawa stopped pursuing this direction after his success with the meson theory, the philosophy behind it was articulated and practiced by his collaborator Shoichi Sakata, yielding further successes. The two-meson theory was one such example. At any rate, Yukawa's approach was phenomenological and ad hoc, in that it lacked a theoretical guiding principle of its own, which was perhaps the reason why he stopped pursuing it. This contrasts with the current situation in which gauge theory has established itself as the supreme principle.