Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- Notational conventions
- Errata
- 1 Spin and helicity
- 2 The effect of Lorentz and discrete transformations on helicity states, fields and wave functions
- 3 The spin density matrix
- 4 Transition amplitudes
- 5 The observables of a reaction
- 6 The production of polarized hadrons
- 7 The production of polarized e±
- 8 Analysis of polarized states: polarimetry
- 9 Electroweak interactions
- 10 Quantum chromodynamics: spin in the world of massless partons
- 11 The spin of the nucleon: polarized deep inelastic scattering
- 12 Two-spin and parity-violating single-spin asymmetries at large scale
- 13 One-particle inclusive transverse single-spin asymmetries
- 14 Elastic scattering at high energies
- Appendix 1 The irreducible representation matrices for the rotation group and the rotation functions djλμ(θ)
- Appendix 2 Homogeneous Lorentz transformations and their representations
- Appendix 3 Spin properties of fields and wave equations
- Appendix 4 Transversity amplitudes
- Appendix 5 Common notations for helicity amplitudes
- Appendix 6 The coefficients involved in the parity-invariance relations amongst the dynamical reaction parameters
- Appendix 7 The coefficients involved in the additional invariance constraints on the dynamical reaction parameters for a spin-s particle
- Appendix 8 Symmetry properties of the Cartesian reaction parameters
- Appendix 9 ‘Shorthand’ notation and nomenclature for the Argonne Lab reaction parameters
- Appendix 10 The linearly independent reaction parameters for various reactions and their relation to the helicity amplitudes
- Appendix 11 The Feynman rules for QCD
- Appendix 12 Dirac spinors and matrix elements
- References
- Index
7 - The production of polarized e±
Published online by Cambridge University Press: 13 January 2010
- Frontmatter
- Contents
- Preface
- Acknowledgements
- Notational conventions
- Errata
- 1 Spin and helicity
- 2 The effect of Lorentz and discrete transformations on helicity states, fields and wave functions
- 3 The spin density matrix
- 4 Transition amplitudes
- 5 The observables of a reaction
- 6 The production of polarized hadrons
- 7 The production of polarized e±
- 8 Analysis of polarized states: polarimetry
- 9 Electroweak interactions
- 10 Quantum chromodynamics: spin in the world of massless partons
- 11 The spin of the nucleon: polarized deep inelastic scattering
- 12 Two-spin and parity-violating single-spin asymmetries at large scale
- 13 One-particle inclusive transverse single-spin asymmetries
- 14 Elastic scattering at high energies
- Appendix 1 The irreducible representation matrices for the rotation group and the rotation functions djλμ(θ)
- Appendix 2 Homogeneous Lorentz transformations and their representations
- Appendix 3 Spin properties of fields and wave equations
- Appendix 4 Transversity amplitudes
- Appendix 5 Common notations for helicity amplitudes
- Appendix 6 The coefficients involved in the parity-invariance relations amongst the dynamical reaction parameters
- Appendix 7 The coefficients involved in the additional invariance constraints on the dynamical reaction parameters for a spin-s particle
- Appendix 8 Symmetry properties of the Cartesian reaction parameters
- Appendix 9 ‘Shorthand’ notation and nomenclature for the Argonne Lab reaction parameters
- Appendix 10 The linearly independent reaction parameters for various reactions and their relation to the helicity amplitudes
- Appendix 11 The Feynman rules for QCD
- Appendix 12 Dirac spinors and matrix elements
- References
- Index
Summary
Quite dramatic progress has been made in the production and utilization of polarized e± beams at CERN's LEP, at HERA at DESY and at the Stanford linear collider SLC. The motivation for trying to overcome the tremendous technical problems involved derives from two sources:
(i) the realization that longitudinally polarized electrons permit extremely accurate measurement of the fundamental parameters of the Standard Model of electroweak interactions;
(ii) the discovery in 1987, by the European Muon Collaboration (Ashman et al., 1988), that only a very small fraction of the proton's spin appeared to be carried by its quarks, leading to what was characterized as a ‘crisis in the parton model’ (Leader and Anselmino, 1988). This made it important to carry out further studies of deep inelastic lepton–hadron scattering using longitudinally polarized leptons colliding with a longitudinally polarized proton target.
Though not a primary impetus, it turns out also that polarized e± permit an exceedingly accurate calibration of the beam energy at LEP and HERA.
The problems involved in having stable polarized beams are quite different in circular storage rings and in linear accelerators. Hence we shall discuss the two cases separately.
The natural polarization of electrons circulating in a perfect storage ring
As mentioned in the introduction to Chapter 6, in principle a circulating electron beam gradually acquires a natural polarization in which its magnetic moment μe becomes aligned parallel to the guide field B.
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- Chapter
- Information
- Spin in Particle Physics , pp. 165 - 184Publisher: Cambridge University PressPrint publication year: 2001