Photon-hadron Interactions

Richard P. Feynman

• Publisher: CRC Press
• Year: 2018
• Print ISBN: 9780367841553
• eBook ISBN: 9780429972966
• Topic: Physical Sciences
• Subtopic: Physics
• Index: Physics

In these classic lectures, Feynman analyses the theoretical questions related to electron and photon interactions at high energies. These lectures are based on a special topics course taught by Feynman at Caltech in 1971 and 1972. The material is dealt with on an advanced level and includes discussions of vector meson dominance and deep inelastic scattering. The possible consequences of the parton model are also analyzed.

General Theoretical Background

Lecture 1

One very powerful way of experimentally investigating the strongly interacting particles (hadrons) is to look at them, to probe them with a known particle; in particular the photon (no other is known as well). This permits a much finer control of variables, and probably decreases the theoretical complexity of the interactions. For example in an ordinary hadron-hadron collision like πp → πp we are hitting two unknowns together, and further, we can only vary the energy, we cannot vary the q² of the pion which must be ${\text{m}}_{\text{π}}{}^2$. In fact a “pion far off its mass shell” may be a meaningless – or at least highly complicated idea. On the other hand in γ + p → p + π we know the γ is single and definite, and we can vary the q² of the γ by using virtual γ’s via, for example, electron scattering e + p → e + p + π.

We are assuming that we do know the photon. QED has been checked so closely that we know that if the photon propagator were off by a factor of the form (1 – q²/Λ²)⁻¹ then Λ exceeds 4 or 5 GeV. The amplitudes are known to about 5% for q² as high as (1 GeV)². For the rest of...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Editor’s Foreword
• Special Preface
• Vita
• Preface
• 1-5 GENERAL THEORETICAL BACKGROUND
• 6-8 LOW ENERGY PHOTON REACTIONS
• 8-10 QUARK MODEL OF RESONANCES
• 11-12 PSEUDOSCALAR MESON PHOTOPRODUCTION, HIGH ENERGY
• 13-14 t-CHANNEL EXCHANGE PHENOMENA
• 14-21 VECTOR MESONS AND VECTOR MESON DOMINANCE HYPOTHESIS
• 22-24 ELECTROMAGNETIC FORM FACTORS
• 25-26 ELECTRON-PROTON SCATTERING. DEEP INELASTIC REGION
• 26-33 PARTON MODEL
• 34-35 TESTS OF THE PARTON MODEL
• 36-37 INELASTIC SCATTERING AS PROPERTIES OF OPERATORS
• 38 LIGHT CONE ALGEBRA
• 39-41 PROPERTIES OF COMMUTATORS IN MOMENTUM SPACE
• 42-47 ELECTROMAGNETIC SELF ENERGY
• 48-49 OTHER TWO-CURRENT EFFECTS
• 50-51 HYPOTHESES IN THE PARTON MODEL
• 52-54 HADRON-HADRON COLLISIONS AT EXTREME ENERGIES
• 55 FINAL HADRONIC STATES IN DEEP INELASTIC SCATTERING
• 56-57 PARTONS AS QUARKS
• APPENDIX A The Isospin of Quark Fragmentation Products
• APPENDIX B A Test of Partons as Quarks
• INDEX