A problem with the Standard Model is the question of why is it that the W⁺, W^-, and Z⁰ particles that mediate the weak force have mass, while the other force carriers, the photon, eight gluons, and graviton, are massless. A new ingredient for the formulation of gauge theories was introduced by F. Englert and Robert H. Brout of the University of Brussels, and by Peter Higgs of the University of Edinburgh. They found a way to endow some of the Yang-Mills fields with mass while retaining exact gauge symmetry. This technique is now called the Higgs Mechanism.

The fundamental idea of the Higgs Mechanism is to include in the theory an extra field, one having the unusual property that it does not vanish in the vacuum. You usually think of vacuum as space with nothing in it, but in physics, vacuum is defined as the state in which all fields have their lowest possible energy. For most fields, the energy is minimized when the value of the field is zero everywhere. An electron field, for instance, has its minimum energy when there are no electrons. The Higgs field is unusual in this respect. Reducing it to zero costs energy. The energy of the field is smallest when the field has some uniform value greater than zero. Therefore, Higgs particles will exist in any vacuum.

The effect of the Higgs field is to provide a frame of reference in which the orientation of the isotropic arrow can be determined. The Higgs field can be represented as an arrow superimposed on the other isotropic indicators in the imaginary internal space of the hadron. What distinguishes the arrow of the Higgs field is that it has a fixed length, established by the vacuum of the field. The orientation of the other isotropic spin arrows can then be measured with respect to the axis defined by the Higgs field. In this way, a proton can be distinguished from a neutron.

Before symmetry breaking, you have two neutral Higgs particles (H⁰), one negative Higgs particle (H^-), and one positive Higgs particle (H⁺). After symmetry breaking, you have one neutral Higgs particle, H⁰, and the three intermediate vector bosons: W⁺, W^-, and Z⁰.