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
10 - Quantum chromodynamics: spin in the world of massless partons
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
Quantum chromodynamics (QCD) is the beautiful theoretical structure believed to control the strong interactions of elementary particles. On the one hand, being a theory of strong interactions it is surprising that one can attack certain problems by perturbative methods, and where this has been done the agreement between theory and experiment is generally impressive. On the other hand a number of non-perturbative problems, which used to seem intractable, are now being attacked by lattice methods, but it is too early to say how significant the results are vis-à-vis experiment.
Because the theory deals with partons (quarks and gluons), whereas experiments are performed with hadrons, there is always some uncalculable piece in any theoretical treatment of a reaction. Consequently there is, to date, no single crucial experiment, which, analogous to the Lamb shift in QED, could be said to prove or disprove the validity of QCD. It is thus important to test the theory in as many ways as possible.
Historically, spin-dependent experiments have played a seminal rôle in verifying or falsifying theories. QCD has a very simple and clear-cut spin structure, so that the study of spin-dependent reactions should provide an excellent way to probe and test the theory further. In fact, as we shall see in Section 14.3 there is apparently serious disagreement between theory and experiment in several reactions, but it is now believed that this is a result of the naivety of the calculations.
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- Chapter
- Information
- Spin in Particle Physics , pp. 258 - 297Publisher: Cambridge University PressPrint publication year: 2001