Difference between revisions of "Loop-induced"

In [[perturbative quantum field theory]], a '''loop-induced''' effect refers to any mechanism which is induced exclusively by [[loop diagrams]]. If no [[Tree level|tree-level]] coupling exists in the [[Lagrangian]] between a particular set of fields (for example, the [[Higgs boson]], which carries no [[colour charge]] and [[Gluon|gluons]]), and their lowest order correlation functions in perturbation theory are instead mediated through a closed loop of virtual particles (such as the [[top quark]]), this coupling is said to be loop induced. In cases where symmetries of the classical theory are broken for the first time by loop diagrams, these effects are said to generate [[Anomaly|anomalies]] of the quantum theory.