Vacuum polarization

Vacuum polarization is a quantum-electrodynamic effect in which quantum fluctuations alter electromagnetic fields, changing how electric charge and photons behave in empty space.

Quantum electrodynamics: The quantum field theory describing interactions between charged particles and electromagnetic fields. Vacuum polarization is one of its quantum corrections to electromagnetic interactions.
Hans Bethe: A German-American physicist who made foundational contributions to nuclear physics and quantum electrodynamics. His 1947 Lamb-shift calculation helped establish the need for radiative corrections.
Hydrogen atom: The simplest atom, consisting of one proton and one electron. Vacuum polarization slightly shifts its energy levels, including the Lamb shift.
Electron self-energy: A quantum correction to an electron's energy arising from its interaction with its own electromagnetic field. It is another radiative correction, but modifies the charged particle rather than the photon field.
Photon propagator: A mathematical function describing how a photon propagates between interactions in quantum field theory. Vacuum polarization modifies the photon propagator through a charged-particle loop.
Julian Schwinger: An American theoretical physicist who developed a covariant formulation of quantum electrodynamics. He supplied a systematic framework for calculating radiative corrections, including vacuum polarization.
Muonium: An exotic atom composed of an antimuon and an electron. Its measured energy levels test vacuum-polarization calculations with high precision.
Vertex correction: A quantum correction to the interaction vertex between charged particles and photons. It changes the interaction point, unlike vacuum polarization's correction to photon propagation.
Feynman diagram: A diagrammatic method for representing terms in perturbative quantum field calculations. A closed charged-particle loop depicts the leading vacuum-polarization contribution.
Richard Feynman: An American theoretical physicist who developed path-integral methods and diagrammatic techniques for quantum electrodynamics. His diagrams made loop contributions to electromagnetic processes calculable.

Linked from 11 pages