Titlebook: Applied Asymptotic Expansions in Momenta and Masses; Vladimir A. Smirnov Book 2002 Springer-Verlag Berlin Heidelberg 2002 Feynman diagrams

Anticoagulants

Sudakov Limits,e of the momentum transfer . . ≡ −(. . − . .). is large compared with the masses, and, for the four-point amplitudes, the Mandelstam variables . = (. . + . .)., . = (. . − . .). are larger than the masses. In the latter case, one has . = −.(1 − cos.)/2 in the centre-of-mass frame, so that this limit is connected with scattering at fixed angles.

温顺

Introduction,ntary-particle physics. In this book, it is explained how this problem is solved. To characterize, briefly, the main steps of the solution let us consider, for example, the process of . . . . annihilation, where an incoming electron and positron produce, according to the quantum-theoretical descript

Ejaculate

parasite

Why, Where and How to Expand,This is generally a rather complicated problem. It usually happens, however, that the parameters involved differ in scale so that it is reasonable to expand the diagram in their small ratio. We shall see in this book that an asymptotic expansion in an arbitrary limit with two scales can be written e

Outwit

monochromatic

Large-Mass Expansion,momentum expansion, so that we apply the method of expansion by subgraphs again here. We start with a one-loop example and then formulate general prescriptions. These prescriptions are given by the same formula (4.34) as for the off-shell large-momentum limit, with a suitable change of the class of

庄严

光滑

Threshold Expansion. Two Masses in the Threshold,We shall usually consider the case of two equal non-zero masses in the threshold, so that we shall typically deal with expansion at . . → 4. .. Guided by expansion by regions, we start with one-loop examples and a two-loop example, which will help us to characterize all the relevant regions, i.e. ha