That model of this phenomenon was developed by Weinberg and Salam and is used to explain the Higgs mechanism.
The value square root of the coefficient of the kinetic term of the pion's low-energy action can be used to measure the magnitude of the "chiral" type of this phenomenon. When it occurs as a system cools, the order parameter's expectation value must be a  finite value. One example of this phenomenon arises from the use of a "Mexican hat potential" coupled to an electromagnetic term. That model of this phenomenon was developed by Weinberg and Salam and is used to explain the Higgs mechanism. The "explicit" type of this phenomenon is caused directly by terms in a system's equations of motion. Yoichiro Nambu took half of the 2008 Nobel Prize in Physics for finding its mechanism in strong interactions. With a Goldstone boson corresponding to each example of the spontaneous variety, for 10 points, identify this phenomenon in which small perturbations prevent a system from becoming invariant under operations such as time-reversal, rotation, or translation.
The value square root of the coefficient of the kinetic term of the pion's low-energy action can be used to measure the magnitude of the "chiral" type of this phenomenon.
symmetry breaking