Evolution of the pion wave function in the scalar $\varphi^3_{(6)}$ model: Two-loop calculation

For the example of the $\varphi^3_{(6)}$ model, the structure of the evolution kernels $V(x,y)$ and $P(z)$ is investigated in the two-loop approximation. The properties of the solution of the evolution equation for $b_0\neq 0$ are analyzed. In the case $b_0=0$ (which corresponds to the absence of charge renormalization in the one-loop approximation), the explicit form of the multiplicatively renormalizable composite operators is found. It is shown that these operators are not identical to conformal tensors, though they have a similar structure.