ESHS/HSS Annual Meeting

The Evolution of Steven Weinberg's Conception of Effective Field Theories in the 1970s

• In Event: Developments in the History of Particle Physics

English Abstract

Effective field theories (EFTs) play a central role in contemporary physics, from subatomic particle physics to early universe cosmology. Yet their history remains largely underexplored. This talk traces the evolution of Steven Weinberg's mature conception of EFTs in the 1970s. I first briefly present Weinberg's early concept of effective theory in 1966-1968, namely, a covariant model expansion in some characteristic scale, built up independently of more fundamental models. Then, I discuss the impact of three main theoretical developments on Weinberg's conception of EFTs in the 1970s: (i) the revival of fundamental field theory in 1971-72 with the perturbative renormalizability proof of spontaneously broken non-abelian gauge theories; (ii) the development of Grand Unified Theories in 1973-1974; (iii) Weinberg's engagement with Wilsonian renormalization group methods in 1975-1976. I argue that none of those developments fundamentally changed Weinberg's distinctive conception of EFTs. At best, (i)-(ii) gave him an overarching framework in which to think about the relation between successive realistic EFTs. In particular, the existence of successive patterns of spontaneous symmetry breaking grounded the relevance of distinct covariant model expansions across scales. The perturbative renormalizability of realistic non-abelian gauge theories, in turn, left open the prospects of a fundamental field theory. By contrast, and contrary to what is usually believed, (iii) was somewhat of a missed opportunity. Weinberg did not incorporate much of Kenneth Wilson's take on EFTs. At best, Wilson's works gave him yet another instance of the physical relevance of perturbatively non-renormalizable models.

Author

• Sebastien Rivat, MCMP, LMU Munich