Electroweak theory

Definition

Electroweak theory is a unified framework that describes two of the four fundamental forces: electromagnetism and the weak nuclear force. It was developed in the 1970s and forms a key part of the Standard Model of particle physics.

5 Must Know Facts For Your Next Test

1. The electroweak theory was formulated by Sheldon Glashow, Abdus Salam, and Steven Weinberg, for which they received the Nobel Prize in Physics in 1979.
2. It predicts the existence of W and Z bosons, which were later experimentally confirmed.
3. Electromagnetic and weak interactions are described by different components of a single gauge symmetry group, $SU(2)_L \times U(1)_Y$.
4. Spontaneous symmetry breaking through the Higgs mechanism gives mass to the W and Z bosons while leaving photons massless.
5. The unification occurs at high energy levels where electromagnetic and weak forces become indistinguishable.

Review Questions

• What are the gauge bosons predicted by electroweak theory?
• How does spontaneous symmetry breaking relate to electroweak theory?
• At what energy levels do electromagnetic and weak forces unify according to electroweak theory?

Related terms

Standard Model: A theory describing three of the four known fundamental forces (electromagnetic, weak, and strong interactions) as well as classifying all known elementary particles.

Higgs Mechanism: A process by which gauge bosons can acquire mass through spontaneous symmetry breaking in gauge theories.

$W$ and $Z$ Bosons: Elementary particles that mediate the weak force; their discovery provided strong support for electroweak theory.