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We evaluate all the primitive divergences contributing to the 7–loop β–function of φ 4 theory, i.e. all 59 diagrams that are free of subdivergences and hence give scheme– independent contributions. Guided by the association of diagrams with knots, we obtain analytical results for 56 diagrams. The remaining three diagrams, associated with the knots 10 124 ,(More)
We present the full analytic result for the three loop angle-dependent cusp anomalous dimension in QCD. With this result, infrared divergences of planar scattering processes with massive particles can be predicted to that order. Moreover, we define a closely related quantity in terms of an effective coupling defined by the lightlike cusp anomalous(More)
I discuss methods of calculation of propagator diagrams (massless, those of Heavy Quark Effective Theory, and massive on-shell diagrams) up to 3 loops. Integration-by-parts recurrence relations are used to reduce them to linear combinations of basis integrals. Non-trivial basis integrals have to be calculated by some other method, e.g., using Gegenbauer(More)
The large-β 0 limit of QCD is discussed, with the emphasize on simple technical methods of calculating various quantities at the order 1/β 0. Many examples, mainly from heavy quark physics, are considered. Some QCD results based on renormaliza-tion group (and not restricted to the large-β 0 limit) are also discussed. It is well known that perturbative(More)
The classical Lagrangian of chromodynamics, its quantization in the perturbation theory framework, and renormalization form the subject of these lectures. Symmetries of the theory are discussed. The dependence of the coupling constant α s on the renormalization scale µ is considered in detail.