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
16 - Gluon emission via the bremsstrahlung process
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
Bremsstrahlung emission is an inherent property of all gauge field theories. It can be understood even within classical mechanics, at least for the soft part of the spectrum. Suppose that we consider a charge surrounded by its Coulomb field, which necessarily is extended in space outside the charge. Then suppose that there is a sudden change in the state of motion of the charge itself. The result will be that the outlying field will need some time to readjust to the new situation.
Therefore there will be, as in all other situations of sudden change in physics, a brief interlude of compressions and extensions in the field before it comes back to a stable state. The ensuing radiation field, to be described below, is a bremsstrahlung field. Its properties depend upon the way in which the charge distribution is changed. For a single charge with a sudden momentum transfer, or for the situation when a charge and anticharge suddenly emerge, the bremsstrahlung is essentially of a dipole character. This approximation means that the current contains a direction, the dipole axis, but the size of the interaction region is neglected. We will consider a ‘classical’ current with these properties.
Some warning is needed against taking the classical picture too far. We have shown in Chapter 2 how the method of virtual quanta describes the Coulomb field of a fast-moving charge.
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- The Lund Model , pp. 302 - 317Publisher: Cambridge University PressPrint publication year: 1998