Vacuum expectation value

The vacuum expectation value (also called vacuum condensate) of an operator is its average, expected value in the vacuum. This concept is important for working with correlation functions in quantum field theory. It is also important in spontaneous symmetry breaking. For example the Higgs field has a vacuum expectation value of 250 GeV; this nonzero value allows the Higgs mechanism to work. See also chiral condensate.

See also Wightman axioms, correlation function, vacuum energy, dark energy.