Content deleted Content added
Line 269:
and
:<math>\int \exp\left[ i \int d^4x \left ( \frac 1 2 \varphi \hat A \varphi + J\varphi \right) \right ] D\varphi \; \propto \; \exp \left( { -i\over 2} \int d^4x \; d^4y J(x) D( x - y) J(y) \right).</math>
See [[Static forces and virtual-particle exchange#Path-integral formulation of virtual-particle exchange|Path-integral formulation of virtual-particle exchange]] for an application of this integral.
| |||