Symmetry breaking

As symmetry breaking (English symmetry breaking; rarely also called symmetry breaking ) is called in physics the violation of a symmetry ( invariance ) and especially the phase transition from one phase or state of higher symmetry in a phase or a state of lower symmetry.

Breaking of a continuous symmetry

An example is a ferromagnet in solid state physics. Above the Curie temperature, the system is rotationally symmetrical, including a magnetization in a predetermined direction is provided. This is an example of the breaking of a continuous symmetry, which is always associated with the appearance of massless excitations, the so-called Goldstone bosons.

Breaking of a discrete symmetry

An example of a broken discrete symmetry is the violation of parity symmetry in the weak interaction (see parity violation ) and the CP violation that one of the conditions for the existence of the visible matter in the universe is in cosmology ( baryon asymmetry ).