If you're talking about QED, the usual textbook procedure is to sum the cross section over all possible configurations with soft photons in the final state. See, e.g., Peskin & Schroeder.ndung200790 said:Please teach me this:
The UV divergence problems are solved by Renormalization Procedure,but I do not understand how to solve IR divergence problems.
An IR divergence, or infrared divergence, is a type of mathematical singularity that occurs in quantum field theory calculations. It arises when the energy of a particle approaches zero, resulting in an infinite contribution to the calculation.
IR divergences occur because of the nature of the interactions between particles in quantum field theory. These interactions become stronger at low energies, leading to infinite contributions to calculations.
IR divergences can make it challenging to extract meaningful physical predictions from quantum field theory calculations. They can also indicate the limitations of the theory and may require additional techniques, such as renormalization, to make predictions.
One approach to solving IR divergences is through the use of resummation techniques, which involve summing an infinite number of terms to cancel out the divergences. Other methods include modifying the theory or using different mathematical tools, such as dimensional regularization.
While many techniques have been developed to deal with IR divergences, there are still open questions and ongoing research in this area. Some theories, such as quantum gravity, also continue to face challenges in dealing with IR divergences.