https://doi.org/10.1007/s100520200905
Theoretical physics
New method for calculating helicity amplitudes of jet-like QED processes for high-energy colliders
LPNHE, IN2P3-CNRS, Université Paris VI, 75252, Paris, France
Institut für Theoretische Physik and NTZ, Universität Leipzig, 04109, Leipzig, Germany
Novosibirsk State University, 630090, Novosibirsk, Russia
* e-mail: carimalo@in2p3.fr
Received:
19
December
2001
Published online:
5
April
2002
Inelastic QED processes, the cross sections of which do not drop with increasing energy, play an important role at high-energy colliders. Such reactions have the form of two-jet processes with the exchange of a virtual photon in the t-channel. We consider them in the region of small scattering angles 
, which yields the dominant contribution to their total cross sections. A new effective method is presented and applied to QED processes with emission of real photons to calculate the helicity amplitudes of these processes. Its basic idea is similar to the well-known equivalent-lepton method. Compact analytical expressions for those amplitudes up to 
are derived omitting only terms of the order of 
and higher order. The helicity amplitudes are presented in a compact form in which large compensating terms are already cancelled. Some common properties for all jet-like processes are found and we discuss their origin.
© Springer-Verlag Berlin Heidelberg / Società Italiana di Fisica, 2002
