Electroweak theory

Electroweak theory unifies electromagnetic and weak interactions in a gauge framework with symmetry group SU(2) × U(1). The Higgs mechanism breaks this symmetry at low energies, leaving electromagnetism and producing massive W and Z bosons.

Electroweak symmetry breaking: The Higgs-field process that breaks electroweak symmetry while leaving electromagnetic gauge symmetry intact. It turns the unified gauge description into the low-energy electromagnetic and weak interactions.
Gauge theory: A field theory built around local symmetries and the gauge fields that implement them. Electroweak theory is defined by its local SU(2) × U(1) gauge symmetry.
Sheldon Glashow: A theoretical physicist who formulated an early gauge theory combining electromagnetic and weak interactions. His 1961 model established a key precursor to the unified theory.
Fermi interaction: A low-energy effective description of weak interactions using a four-fermion contact interaction. It approximates electroweak weak processes when W-boson details are unresolved.
Quantum electrodynamics: The quantum field theory of electromagnetic interactions between charged particles and photons. It is the electromagnetic sector that electroweak theory contains at low energies.
Higgs mechanism: A mechanism in which a field’s nonzero vacuum value gives mass to gauge bosons without explicit mass terms. It gives the W and Z bosons mass while the photon remains massless.
SU(2): The group of two-dimensional unitary matrices with determinant one. It supplies the weak-isospin gauge symmetry of the electroweak model.
Abdus Salam: A theoretical physicist who independently developed electroweak unification and shared the 1979 Nobel Prize for it. His work helped establish the theory alongside Weinberg’s and Glashow’s.
Beta decay: A radioactive decay in which a nucleus changes charge through emission of an electron or positron and a neutrino or antineutrino. It is a familiar weak process described by electroweak theory.
Quantum chromodynamics: The quantum field theory of the strong interaction between quarks and gluons. It is a separate Standard Model gauge theory, not part of electroweak unification.

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