Anomalies (physics)

An instanton (or pseudoparticle) is a notion appearing in theoretical and mathematical physics. An instanton is a classical solution to equations of motion with a finite, non-zero action, either in quantum mechanics or in quantum field theory. More precisely, it is a solution to the equations of motion of the classical field theory on a Euclidean spacetime.

the failure of a symmetry of a theory's classical action to be a symmetry of any regularization of the full quantum theory

thumb|right|300px|An example of a saddle point (in red) on a simple function. A sphaleron ( "slippery") is a static (time-independent) solution to the electroweak field equations of the Standard Model of particle physics, and is involved in certain hypothetical processes that violate baryon and lepton numbers. Such processes cannot be represented by perturbative methods such as Feynman diagrams, and are therefore called non-perturbative. Geometrically, a sphaleron is a saddle point of the electroweak potential (in infinite-dimensional field space).

proposed resolution to the strong CP problem

anomalies that can arise in gauge theories coupled to gravity

term in theoretical physics