We study the process qq → qqg at lowest order in QCD perturbation theory to understand gluon radiation in the fragmentation region of relativistic heavy ion collisions. We arrive at a formula for gluon multiplicity that interpolates between ∼1/k 2 ⊥ behavior at low k ⊥ , to ∼1/k 4 ⊥ at large k ⊥ .

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The renormalizable Kroll-Lee-Zumino field theory of pions and a neutral rho-meson is used to determine the scalar form factor of the pion in the space-like region at next-to-leading order. Perturbative calculations in this framework are parameter-free, as the masses and the rho-pion-pion coupling are known from experiment. Results compare favorably with lattice QCD calculations.

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The Kroll-Lee-Zumino renormalizable Abelian quantum field theory of pionic strong interactions is used to compute the rho-meson propagator at the two-loop level.