Formula_25296

\[\left.\begin{array}{rl}P_{\mu} & =\int\left[a_{\lambda}^{+}(p) a_{\lambda}(p)+\tilde{a}_{\lambda}^{+}(p) \tilde{a}_{\lambda}(p)\right] p_{\mu} d p, \\Q & =e \int\left[a_{\lambda}^{+}(p) a_{\lambda}(p)-\tilde{a}_{\lambda}^{+}(p) \tilde{a}_{\lambda}(p)\right] \boldsymbol{d p}\end{array}\right\}\]