Wellenpaket

$Ψ (\underline{x}, t) = {(2 π)}^{-^{d} ╱_{2}} \int φ (\underline{k}) e^{- ω (\underline{k}) t + \underline{k} . \underline{x}} d^{d} \underline{k}$ d Raumdimension

$ω (\underline{k}) = \sqrt{{\underline{k}}^{2} + m^{2}}$