Renormalization is a fundamental concept in quantum field theory and quantum physics. It is a mathematical technique used to handle certain infinities that arise in the calculations of physical quantities within the framework of quantum field theories.
In quantum field theory, particles and their interactions are described by fields that pervade spacetime. When calculating the properties of these fields and their interactions, such as particle masses or interaction strengths, one often encounters divergent quantities. These divergences arise due to the self-interactions of particles and the inherent structure of the theory.
Renormalization provides a systematic way to remove these infinities and obtain meaningful and finite predictions from the theory. The process involves introducing counterterms, which are additional terms in the theory's equations that cancel out the infinities, leaving behind finite, observable quantities.
There are different types of renormalization techniques, such as perturbative renormalization, where calculations are done iteratively in terms of a coupling constant, and non-perturbative renormalization, which addresses certain situations where perturbation theory breaks down.
Renormalization is a powerful tool that has been successfully applied in various areas of quantum physics, including quantum electrodynamics (QED), the quantum field theory describing the electromagnetic interaction, as well as the strong and weak nuclear forces described by quantum chromodynamics (QCD) and the electroweak theory, respectively.
Overall, renormalization allows physicists to make meaningful predictions and compare them with experimental results, reconciling the divergences encountered in quantum field theory calculations and providing a solid foundation for our understanding of the microscopic world.