Ph.D., University of Cambridge, 1975

Mailing address: 104 Davey Lab. #208, Penn State University, University Park PA 16802, U.S.A.

jcc8@psu.edu

Elementary Particles and Fields

The theory of the strong nuclear interaction is quantum chromodynamics (QCD). Protons and other strongly interacting particles are bound states of quarks held together by what is called a "gluon field". A key property of QCD is "asymptotic freedom". This means that on long distance scales the interaction is strong, so that quarks are permanently confined, but that on shorter distance scales the interaction becomes progressively weaker. In principle, QCD should be able to predict the properties of atomic nuclei from first principles, but, in practice, this is very difficult because one has to treat strong coupling, relativistic many-body dynamics.

In the twenty years since the discovery of QCD, substantial progress has nevertheless been made in understanding the consequences of the theory. Much of the progress has been concerned with phenomena that occur on distance scales smaller than the size of a proton, for there one can try to exploit the weakness of the interactions that is a consequence of asymptotic freedom. Prof. Collins has played an important role in this work.

Originally, calculations in QCD were possible only for a few exotic processes. As experiments on elementary particle collisions have progressed to higher and higher energies, the products of the collisions have become more complex, but at the same time they probe shorter distances. The quantitative predictions that can now be made from first principles, for a wide range of processes, are in substantial agreement with experiment. In obtaining these predictions, Prof. Collins and many others have discovered interesting mathematical properties of the theory. Only with the aid of these results, can one interpret experimental data from modern high energy particle accelerators.

The result is that these accelerators can now be used in effect as microscopes which probe fundamental physics at distance scales that are now of the order of a hundredth or a thousandth of the size of a proton. One aim of current research in elementary particle physics is to discover what lies inside the many known "elementary" particles, and what causes them to have the properties that they have. In these investigations, the results of QCD calculations play a critical role.

Prof. Collins is an emeritus member of the CTEQ Collaboration, which is a collaboration of experimentalists and theorists at many universities and laboratories who work on QCD.

- John Collins, Foundations of Perturbative QCD (Cambridge University Press, 2011). Errata can be found here.
- John Collins, Renormalization: an introduction to renormalization, the renormalization group and the operator product expansion, (Cambridge University Press, Cambridge, 1984). The available formats are: Open Access pdf file, paperback, hardback. Errata can be found here. Russian translation (V.A. Smirnov and O.I. Zavialov trans.) published by Mir, Moscow, 1988.

Selected publications:

- John Collins, Ted C. Rogers, and Nobuo Sato, "Positivity and renormalization of parton densities", Phys. Rev. D 105, 076010 (2022); arXiv:2111.01170.
- John Collins, "Do fragmentation functions in factorization theorems correctly treat non-perturbative effects?", arXiv:1610.09994.
- Garrett Swan, John Collins, and Brad Wyble, "Memory for a single object has differently variable precisions for relevant and irrelevant features", Journal of Vision 16(3), 32 (2016).
- J.C. Collins and T.C. Rogers, "Understanding the large-distance behavior of transverse-momentum-dependent parton densities and the Collins-Soper evolution kernel", Phys. Rev. D91, 074020 (2015); arXiv:1412.3820.
- John Collins, "CSS Equation, etc, Follow from Structure of TMD Factorization", arXiv:1212.5974.
- S. Mert Aybat, John C. Collins, Jian-Wei Qiu, and Ted C. Rogers, "The QCD Evolution of the Sivers Function" arXiv:1110.6428.
- J. Collins, "New definition of TMD parton densities" in Proceedings of QCD Evolution workshop, Jefferson Laboratory, April 8--9, 2011, Int. J. Mod. Phys. Conf. Ser. 4, 85-96 (2011), arXiv:1107.4123.
- J. Collins, "Rapidity divergences and valid definitions of parton densities", in Proceedings of LIGHT CONE 2008 Relativistic Nuclear and Particle Physics July 7-11, 2008, Mulhouse, France, PoS LC2008:028,2008; arXiv:0808.2665.
- J.C. Collins and T.C. Rogers, "The Gluon Distribution Function and Factorization in Feynman Gauge", Phys. Rev. D77, 085009 (2008); arXiv:0805.1752.
- John Collins and Jian-Wei Qiu, "Factorization is violated in production of high-transverse-momentum particles in hadron-hadron collisions", Phys. Rev. D75, 114014 (2007); arXiv:0705.2141
- John Collins, Alejandro Perez, and Daniel Sudarsky, "Lorentz invariance Violation and its Role in Quantum Gravity Phenomenology", in Quantum Gravity, D. Oriti ed. (Cambridge University Press); hep-th/0603002.
- John C. Collins, Aneesh V. Manohar, and Mark B. Wise, "Renormalization of the Vector Current in QED", Phys. Rev. D 73, 105019 (2006); hep-th/0512187.
- J.C. Collins and A. Metz, "Universality of soft and collinear factors in hard-scattering factorization", Phys. Rev. Lett. 93, 252001 (2004); e-Print archive: hep-ph/0408249.
- J. Collins, A. Perez, D. Sudarsky, L. Urrutia, and H. Vucetich, "Lorentz invariance: an additional fine-tuning problem", Phys. Phys. Rev. Lett. 93, 191301 (2004); gr-qc/0403053.
- J.C. Collins, "What exactly is a parton density?" Acta Phys. Polon. B34, 3103 (2003); e-Print archive: hep-ph/0304122
- J.C. Collins, "Leading-twist Single-transverse-spin asymmetries: Drell-Yan and Deep-Inelastic Scattering", Phys. Lett. B536, 43 (2002); e-Print archive: hep-ph/0204004.
- J.C. Collins and Jon Pumplin, "Tests of goodness of fit to multiple data sets", e-print archive: hep-ph/0105207.
- L. Alvero, J.C. Collins, J. Terron and J. Whitmore, "Diffractive Hadronic Production of Jets and Weak Bosons", Phys. Rev. D59, 074022 (1999); e-print archive: hep-ph/9805268.
- J.C. Collins, "Hard-scattering factorization with heavy quarks: A general treatment", Phys. Rev. D 58, 094002 (1998); e-print archive: hep-ph/9806259.
- J.C. Collins, L. Frankfurt and M. Strikman, "Factorization for hard exclusive electroproduction of mesons in QCD", Phys. Rev. D56, 2982 (1997); e-print archive: hep-ph/9611433.
- J.C. Collins, "The Problem of Scales: Renormalization and All That", in "Theoretical Advanced Study Institute in Elementary Particle Physics, 1995: QCD and Beyond", D.E. Soper, ed., (World Scientific Singapore); e-print archive: hep-ph/9510276.
- X. Artru and J.C. Collins, "Measuring transverse spin correlations by 4-particle correlations in e^+ e^- to 2 jets'', Z. Phys. C. 69, 277 (1996); e-print archive: hep-ph/9504220.
- J.C. Collins and D.E. Soper, "Issues in the Determination of Parton Distribution Functions", e-Print archive: hep-ph/9411214.
- CTEQ Collaboration, G. Sterman et al., "Handbook of Perturbative QCD", Rev. Mod. Phys. 67, 157 (1995). Updated version

John Collins, jcc8@psu.edu, 12 November 2023.