Evolving images of the proton: Hadron physics over the past 40 years

Journal Article · Tue Apr 05 04:00:00 UTC 2016 · Journal of Physics. G, Nuclear and Particle Physics

DOI: https://doi.org/10.1088/0954-3899/43/5/054001 · OSTI ID:1248611

Pennington, Michael R. ^[1]

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1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

Once upon a time, the world was simple: the proton contained three quarks, two ups and a down. How these give the proton its mass and its spin seemed obvious. Over the past 40 years the proton has become more complicated, and how even these most obvious of its properties is explained in a universe of quarks, antiquarks and gluons remains a challenge. That this should be so should come as no surprise. Quantum chromodynamics, the theory of the strong interaction, is seemingly simple, and its consequences are straightforward in the domain of hard scattering where perturbation theory applies. However, the beauty of the hadron world is its diversity. The existence of hadrons, their properties, and their binding into nuclei do not appear in the Lagrangian of QCD. They all emerge as a result of its strong coupling. Strong coupling QCD creates complex phenomena, much richer than known 40 years ago: a richness that ensures colour confinement and accounts for more than 95% of the mass of the visible Universe. How strong coupling QCD really works requires a synergy between experiment and theory. Furthermore, a very personal view of these fascinating developments in cold QCD is presented.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
• Grant/Contract Number: AC05-06OR23177
• OSTI ID: 1248611
• Report Number(s): JLAB-THY--16-2239; DOE/OR/23177--5061
• Journal Information: Journal of Physics. G, Nuclear and Particle Physics, Journal Name: Journal of Physics. G, Nuclear and Particle Physics Journal Issue: 5 Vol. 43; ISSN 0954-3899
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English