Finance

Physics

Branching (polymer chemistry)

Particle physics

Quantum chromodynamics

Gluon

Inelastic scattering

Composite material

Economics

Parton

Scattering

Materials science

Quantum electrodynamics

Quantum mechanics

Deep inelastic scattering

Momentum (technical analysis)

Quark

Journal of High Energy Physics

We study parton-branching solutions of QCD evolution equations and present a method to construct both collinear and transverse momentum dependent (TMD) parton densities from this approach. We work with next-to-leading-order (NLO) accuracy in the strong coupling. Using the unitarity picture in terms of resolvable and non-resolvable branchings, we analyze the role of the soft-gluon resolution scale in the evolution equations. For longitudinal momentum distributions, we find agreement of our numerical calculations with existing evolution programs at the level of better than 1 percent over a range of five orders of magnitude both in evolution scale and in longitudinal momentum fraction. We make predictions for the evolution of transverse momentum distributions. We perform fits to the high-precision deep inelastic scattering (DIS) structure function measurements, and we present a set of NLO TMD distributions based on the parton branching approach.

Collinear and TMD quark and gluon densities from parton branching solution of QCD evolution equations