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Full-Text Articles in Quantum Physics
What Is A Photon? Foundations Of Quantum Field Theory, Charles G. Torre
What Is A Photon? Foundations Of Quantum Field Theory, Charles G. Torre
All Physics Faculty Publications
This is a brief, informal, and relatively low-level course on the foundations of quantum field theory. The prerequisites are undergraduate courses in quantum mechanics and electromagnetism.
Positivity And Renormalization Of Parton Densities, John Collins, Ted C. Rogers, Nobuo Sato
Positivity And Renormalization Of Parton Densities, John Collins, Ted C. Rogers, Nobuo Sato
Physics Faculty Publications
There have been recent debates about whether MS parton densities exactly obey positivity bounds (including the Soffer bound) and whether the bounds should be applied as a constraint on global fits to parton densities and on nonperturbative calculations. A recent paper [Candido et al., Can MS parton distributions be negative?, J. High Energy Phys. 11 (2020) 129] appears to provide a proof of positivity in contradiction with earlier work by other authors. We examine their derivation and find that its primary failure is in the apparently uncontroversial statement that bare parton density (or distribution) function (pdfs) are always …