Chapter 4 on Richard Feynman, my theoretical physics thesis advisor, is a collection of vignettes that reveal aspects of behavior and thought that contributed to his mystique and unique accomplishments in physics.

After relating the history behind Feynman’s V-A theory of party violation, much of it in Feynman’s own words, the rest of the chapter is based on my personal interactions with Feynman lasting for a little more than twenty years, from the time I arrived at Caltech in 1959 till I left in 1981. Feynman’s attitude towards experimental results related to parity violation provides an informative background to how he would handle experimental information related to the discovery of quarks. The intent here, and in the remainder of the Chapter, is to give the reader a sense of how Feynman thought about physics, how he practiced it, and what he valued. His struggle with constituent quarks (aces), and what to make of them, lasted considerably longer than a decade, passing though several phases, including one with partons, but eventually ending with his fully accepting their reality.

In high-energy scattering processes, hadrons can be described as a set of partons. This picture is compatible with QCD, where the partons are identified as quarks, anti-quarks, and gluons. In this picture, we consider electron–positron annihilation, which can lead to hadrons or a muon–anti-muon pair. The R-ratio of the cross sections for these scenarios allows us to identify the number of colors, Nc = 3, experimentally. Next we discuss deep inelastic electron–nucleon scattering, which leads to the concepts of the Bjorken variable, structure functions, the parton distribution function, Bjorken scaling, the Callan–Gross relation, and the DGLAP evolution equation. The hadronic tensor takes us to the scaling functions, where high-energy neutrino–nucleon scattering provides further insight, in particular a set of constraints which are expressed as sum rules.