The concept of a nonlocal Lagrangian refers to a type of Lagrangian formulation in field theory where the interactions (or kinetic and potential terms) are not strictly local in space and time. In contrast, a local Lagrangian depends only on field values at a single point in spacetime and their derivatives at that point. A nonlocal Lagrangian, however, may involve fields evaluated at multiple points, typically through integrals or specific nonlocal functions.
New to topics? Read the docs here!