Book contents
- Frontmatter
- Contents
- Acknowledgements
- 1 Introduction
- 2 Relativistic kinematics, electromagnetic fields and the method of virtual quanta
- 3 The harmonic oscillator and the quantum field
- 4 The vacuum as a dielectric medium; renormalisation
- 5 Deep inelastic scattering and the parton model
- 6 The classical motion of the massless relativistic string
- 7 The decay kinematics of the massless relativistic string
- 8 A stochastic process for string decay
- 9 The properties of the Lund model fragmentation formulas; the external-part formulas
- 10 The internal-part fragmentation formulas and their relations to the unitarity equations of a field theory; Regge theory
- 11 The dynamical analogues of the Lund model fragmentation formulas
- 12 Flavor and transverse momentum generation and the vector meson to pseudoscalar meson ratio
- 13 Heavy quark fragmentation and baryon production
- 14 The Hanbury-Brown-Twiss effect and the polarisation effects in the Lund model
- 15 The Lund gluon model, its kinematics and decay properties
- 16 Gluon emission via the bremsstrahlung process
- 17 Multigluon emission, the dipole cascade model and other coherent cascade models
- 18 The λ-measure in the leading-log and modified leading-log approximations of perturbative QCD
- 19 The parton model and QCD
- 20 Inelastic lepto-production in the Lund model, the soft radiation model and the linked dipole chain model
- References
- Index
3 - The harmonic oscillator and the quantum field
Published online by Cambridge University Press: 23 September 2009
- Frontmatter
- Contents
- Acknowledgements
- 1 Introduction
- 2 Relativistic kinematics, electromagnetic fields and the method of virtual quanta
- 3 The harmonic oscillator and the quantum field
- 4 The vacuum as a dielectric medium; renormalisation
- 5 Deep inelastic scattering and the parton model
- 6 The classical motion of the massless relativistic string
- 7 The decay kinematics of the massless relativistic string
- 8 A stochastic process for string decay
- 9 The properties of the Lund model fragmentation formulas; the external-part formulas
- 10 The internal-part fragmentation formulas and their relations to the unitarity equations of a field theory; Regge theory
- 11 The dynamical analogues of the Lund model fragmentation formulas
- 12 Flavor and transverse momentum generation and the vector meson to pseudoscalar meson ratio
- 13 Heavy quark fragmentation and baryon production
- 14 The Hanbury-Brown-Twiss effect and the polarisation effects in the Lund model
- 15 The Lund gluon model, its kinematics and decay properties
- 16 Gluon emission via the bremsstrahlung process
- 17 Multigluon emission, the dipole cascade model and other coherent cascade models
- 18 The λ-measure in the leading-log and modified leading-log approximations of perturbative QCD
- 19 The parton model and QCD
- 20 Inelastic lepto-production in the Lund model, the soft radiation model and the linked dipole chain model
- References
- Index
Summary
Introduction
In this and the next chapter we will consider some properties of quantum fields. The examples taken will be mostly scalar fields and only when necessary will we invoke the complexities stemming from the vector nature of the interactions in QED and QCD; there are many good text-books devoted to a detailed treatment of the subject.
We need only intuition and a set of understood formulas for the investigations contained in this book. We start with a discussion of the quantum mechanical harmonic oscillator coupled to an external force. There are several reasons to dwell on this particular system. Firstly its sine and cosine behaviour in time is matched by the corresponding harmonic behaviour of the plane wave solutions for the quanta in a field theory.
It was noted even in the first papers on quantum field theory that a free or weakly interacting quantum field is in a rather precise way a superposition of an infinite, although enumerable, set of harmonic oscillators, one for each degree of freedom.
A real interacting-field theory does not behave in this way with respect to its excitations. There is always, however, at the basis of any experiment in high-energy particle physics the idea of a three-act scenario in time.
- Type
- Chapter
- Information
- The Lund Model , pp. 27 - 56Publisher: Cambridge University PressPrint publication year: 1998