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arXiv · hep-ph/0002225

Exact and Broken Symmetries in Particle Physics

R. D. Peccei
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Abstract

In these lectures, I discuss the role of symmetries in particle physics. I begin by discussing global symmetries and show that they can be realized differently in nature, depending on whether or not the vacuum state is left invariant by the symmetry. I introduce next the notion of local symmetries and show how these symmetries can be implemented through the introduction of gauge fields. Using the simple example of a spontaneously broken U(1) symmetry, I discuss the Higgs mechanism showing that it provides a natural way for the gauge fields to acquire mass. Finally, I show how these concepts are used as the basis for the Standard Model of particle physics, ending with a brief description of some of the salient aspects of Quantum Chromodynamics and of the electroweak theory.

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R. D. Peccei. 2000-02-21. Exact and Broken Symmetries in Particle Physics. https://arxiv.org/abs/hep-ph/0002225

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