 Relativistic quantum field

A relativistic quantum field is a quantum field whose transformation and dynamics are compatible with special relativity. A scalar field, a Dirac field and a gauge field transform differently under Lorentz transformations, reflecting their different spin content.

Relativistic consistency also constrains locality. Microcausality requires local physical observables at spacelike separation to commute, so an operation in one region cannot immediately change measurement statistics in the other. Vacuum correlations across spacelike separation do not contradict that requirement. Field excitations can describe particles and antiparticles, allowing creation and annihilation processes when conserved quantities and available energy permit them. An interacting theory's observables therefore cannot generally be organized using one permanently fixed particle number.