Formula_22963

\[\begin{gathered}S_{2}=-\int a^{+}(x) K(x, y) a(x) d x d y=a^{+} K a \\S_{1}=\int\left[a^{+}(x) \eta(x)+\eta^{+}(x) a(x)\right] d x=\eta^{+} a+a^{+} \eta, \\D \mu=\prod_{x} d a^{+}(x) d a(x)\end{gathered}\]