Eq. (4.4): $\sum_{\rm perm}i\int_{-\infty}^0 d\eta\,k_1^2k_2^2e^{ik_t\eta}+{\rm c.c.} = 4\frac{\sum_{i>j}k_i^2k_j^2}{k_t}$

Initializing...

Eq. (4.4): $\sum_{\rm perm}i\int_{-\infty}^0 d\eta\,k_1^2k_2^2e^{ik_t\eta}+{\rm c.c.} = 4\frac{\sum_{i>j}k_i^2k_j^2}{k_t}$ · Prove2Me