1964 PRL symmetry breaking papers

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Five of the six 2010 Sakurai Prize winners — Kibble, Guralnik, Hagen, Englert, and Brout
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In 1964 three teams proposed related but different approaches to explain how mass could arise in local gauge theories. These three, now famous, papers were written by Robert Brout and François Englert,[1][2] Peter Higgs,[3] and Gerald Guralnik, C. Richard Hagen, and Tom Kibble,[4][5] and are credited with the prediction of the Higgs boson and Higgs mechanism which provides the means by which gauge bosons can acquire non-zero masses in the process of spontaneous symmetry breaking.[6] The mechanism is the key element of the electroweak theory that forms part of the Standard Model of particle physics, and of many models, such as the Grand Unified Theory, that go beyond it. The papers that introduce this mechanism were published in Physical Review Letters (PRL) and were each recognized as milestone papers by PRL's 50th anniversary celebration.[7] Additionally, all of the six physicists were awarded the 2010 J. J. Sakurai Prize for Theoretical Particle Physics for this work.[8]

On 4 July 2012, the two main experiments at the LHC (ATLAS and CMS) both reported independently the confirmed existence of a previously unknown particle with a mass of about 125 GeV/c2 (about 133 proton masses, on the order of 10−25 kg), which is "consistent with the Higgs boson" and widely believed to be the Higgs boson.[9]

Contents

Introduction [edit]

A gauge theory of elementary particles is a very attractive potential framework for constructing the ultimate theory. Such a theory has the very desirable property of being potentially renormalizable—shorthand for saying that all calculational infinities encountered can be consistently absorbed into a few parameters of the theory. However, as soon as one gives mass to the gauge fields, renormalizability is lost, and the theory rendered useless. Spontaneous symmetry breaking is a promising mechanism, which could be used to give mass to the vector gauge particles. A significant difficulty which one encounters, however, is Goldstone's theorem, which states that in any quantum field theory which has a spontaneously broken symmetry there must occur a zero-mass particle. So the problem arises—how can one break a symmetry and at the same time not introduce unwanted zero-mass particles. The resolution of this dilemma lies in the observation that in the case of gauge theories, the Goldstone theorem can be avoided by working in the so-called radiation gauge. This is because the proof of Goldstone's theorem requires manifest Lorentz covariance, a property not possessed by the radiation gauge.

Manifest covariance overview [edit]

Most students who have taken a course in electromagnetism have encountered the Coulomb potential. It basically states that two charged particles attract or repel each other by a force which varies according to the inverse square of their separation. This is fairly unambiguous for particles at rest, but if one or the other is following an arbitrary trajectory the question arises whether one should compute the force using the instantaneous positions of the particles or the so-called retarded positions. The latter recognizes that information cannot propagate instantaneously, rather it propagates at the speed of light. Now the radiation gauge says that one uses the instantaneous positions of the particles, but doesn't violate causality because there are compensating terms in the force equation. In contrast, the Lorenz gauge imposes manifest covariance (and thus causality) at all stages of a calculation. Predictions of observable quantities are identical in the two gauges, but the radiation gauge formulation of quantum field theory conveniently avoids Goldstone's theorem.[10]

Combined contributions [edit]

Each of these papers is unique and demonstrates different approaches to showing how mass arise in gauge particles. Over the years, the differences between these papers are no longer widely understood, due to the passage of time and acceptance of end-results by the particle physics community. A study of citation indices is interesting—more than 40 years after the 1964 publication in Physical Review Letters there is little noticeable pattern of preference among them, with the vast majority of researchers in the field mentioning all three milestone papers.[citation needed]

See also [edit]

References [edit]

  1. ^ Englert, F.; Brout, R. (1964). "Broken Symmetry and the Mass of Gauge Vector Mesons". Physical Review Letters 13 (9): 321. doi:10.1103/PhysRevLett.13.321.  edit
  2. ^ R. Brout, F. Englert (1998). "Spontaneous Symmetry Breaking in Gauge Theories: A Historical Survey". arXiv:hep-th/9802142 [hep-th].
  3. ^ Higgs, P. (1964). "Broken Symmetries and the Masses of Gauge Bosons". Physical Review Letters 13 (16): 508. doi:10.1103/PhysRevLett.13.508.  edit
  4. ^ Guralnik, G.; Hagen, C.; Kibble, T. (1964). "Global Conservation Laws and Massless Particles". Physical Review Letters 13 (20): 585. doi:10.1103/PhysRevLett.13.585.  edit
  5. ^ G.S. Guralnik (2009). "The History of the Guralnik, Hagen and Kibble development of the Theory of Spontaneous Symmetry Breaking and Gauge Particles". International Journal of Modern Physics A 24 (14): 2601–2627. arXiv:0907.3466. Bibcode:2009IJMPA..24.2601G. doi:10.1142/S0217751X09045431. 
  6. ^ Kibble, T. (2009). "Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism". Scholarpedia 4: 6441–6410. doi:10.4249/scholarpedia.6441.  edit
  7. ^ M. Blume, S. Brown, Y. Millev (2008). "Letters from the past, a PRL retrospective (1964)". Physical Review Letters. Archived from the original on 10 January 2010. Retrieved 2010-01-30. 
  8. ^ "J. J. Sakurai Prize Winners". American Physical Society. 2010. Archived from the original on 12 February 2010. Retrieved 2010-01-30. 
  9. ^ "CERN experiments observe particle consistent with long-sought Higgs boson". CERN press release. 4 July 2012. Retrieved 4 July 2012. 
  10. ^ G.S. Guralnik, C.R. Hagen, T.W.B. Kibble (1968). "Broken Symmetries and the Goldstone Theorem". In R. L. Cool, R. E. Marshak. Advances in Particle Physics 2. Interscience Publishers. pp. 567–708. ISBN 0-470-17057-3. 

Further reading [edit]

External links [edit]

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