Book contents
- Frontmatter
- Contents
- Preface
- A note on choice of metric
- Text website
- Part 1 Effective field theory: the Standard Model, supersymmetry, unification
- Part 2 Supersymmetry
- Part 3 String theory
- 20 Introduction
- 21 The bosonic string
- 22 The superstring
- 23 The heterotic string
- 24 Effective actions in ten dimensions
- 25 Compactification of string theory I. Tori and orbifolds
- 26 Compactification of string theory II. Calabi–Yau compactifications
- 27 Dynamics of string theory at weak coupling
- 28 Beyond weak coupling: non-perturbative string theory
- 29 Large and warped extra dimensions
- 30 Coda: where are we headed?
- Part 4 The appendices
- References
- Index
20 - Introduction
from Part 3 - String theory
Published online by Cambridge University Press: 17 May 2010
- Frontmatter
- Contents
- Preface
- A note on choice of metric
- Text website
- Part 1 Effective field theory: the Standard Model, supersymmetry, unification
- Part 2 Supersymmetry
- Part 3 String theory
- 20 Introduction
- 21 The bosonic string
- 22 The superstring
- 23 The heterotic string
- 24 Effective actions in ten dimensions
- 25 Compactification of string theory I. Tori and orbifolds
- 26 Compactification of string theory II. Calabi–Yau compactifications
- 27 Dynamics of string theory at weak coupling
- 28 Beyond weak coupling: non-perturbative string theory
- 29 Large and warped extra dimensions
- 30 Coda: where are we headed?
- Part 4 The appendices
- References
- Index
Summary
String theory was stumbled on, more or less, by accident. In the late 1960s, string theories were first proposed as theories of the strong interactions. But, it was quickly realized that, while hadronic physics has a number of string-like features, string theories were not suitable for a detailed description. In their simplest form, string theories had massless spin-two particles and more than four dimensions of spacetime, hardly features of the strong interactions. But a small group of theorists appreciated that the presence of a spin-two particle implied that these theories were generally covariant and explored them through the 1970s and and early 1980s as possible theories of quantum gravity. Like field theories, the number of possible string theories seemed to be infinite, while, unlike field theories, there was reason to believe that these theories did not suffer from ultraviolet divergences. In the 1980s, however, studies of anomalies in higher dimensions suggested that all string theories with chiral fermions and gauge interactions suffered from quantum anomalies. But in 1984, it was shown that anomalies cancel for two choices of gauge group. It was quickly recognized that the non-anomalous string theories do come close to unifying gravity and the Standard Model of particle physics. Many questions remained. Beginning in 1995, great progress was made in understanding the deeper structure of these theories. All of the known string theories were understood to be different limits of some larger structure. As string theories still provide the only framework in which one can do systematic computations of quantum gravity effects, many workers use the term “string theory” to refer to some underlying structure which unifies quantum mechanics, gravity and gauge interactions.
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- Chapter
- Information
- Supersymmetry and String TheoryBeyond the Standard Model, pp. 305 - 312Publisher: Cambridge University PressPrint publication year: 2007