Wightman function
= Wightman function
{wiki}
A <Wightman function> is an unordered vacuum <correlation function>. For a free scalar mode $f_k(t)$, the positive-frequency <two-point function> is $G^>(t_1,t_2;k)=f_k(t_1)f_k^*(t_2)$.
= Wightman function
{wiki}
A <Wightman function> is an unordered vacuum <correlation function>. For a free scalar mode $f_k(t)$, the positive-frequency <two-point function> is $G^>(t_1,t_2;k)=f_k(t_1)f_k^*(t_2)$.