August 11, 2016 9:28 The Standard Theory of Particle Physics - 9.61in x 6.69in b2471-ch02 page 29
Chapter 2
The Making of the Standard Theory
John Iliopoulos Laboratoire de Physique Th´eorique, Ecole´ Normale Sup´erieure, 24 rue Lhomond, 75005 Paris, France
1. Introduction
The construction of the Standard Model, which became gradually the Standard Theory of elementary particle physics, is, probably, the most remarkable achieve- ment of modern theoretical physics. In this Chapter we shall deal mostly with the weak interactions. It may sound strange that a revolution in particle physics was initiated by the study of the weakest among them (the effects of the gravitational interactions are not measurable in high energy physics), but we shall see that the weak interactions triggered many such revolutions and we shall have the occasion to meditate on the fundamental significance of “tiny” effects. We shall outline the various steps, from the early days of the Fermi theory to the recent experimental discoveries, which confirmed all the fundamental predictions of the Theory. We shall follow a phenomenological approach, in which the introduction of every new concept is motivated by the search of a consistent theory which agrees with experiment. As we shall explain, this is only part of the story, the other part being the requirement of mathematical consistency. Both went in parallel and the real history requires the understanding of both. In fact, as we intend to show, the initial motivation was not really phenomenological. It is one of these rare cases in which a revolution in physics came from theorists trying to go beyond a simple phenomenological model,
The Standard Theory of Particle Physics Downloaded from www.worldscientific.com not from an experimental result which forced them to do so. This search led to the introduction of novel symmetry concepts which brought geometry into physics. It is this exciting story which will be presented here. by EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) on 09/20/16. For personal use only.