Analytic properties of the differential cross section of inelastic scattering

Analyticity regions of the differential cross-section $d^2\sigma/d \cos\theta\, d\varphi$ and the function $\Phi$ (see (2)) with respect to $\cos\theta$ at physical values of $\varphi$ are found for the process $a+b\to c+d+f$ in the approximation of pole diagrams. At all energies above the threshold and $0\leq\varphi\leq 2\pi$ for $d^2\sigma/d \cos\theta\, d\varphi$ ($\varphi\neq 0, \pi, 2\pi$ for $\Phi$) these regions include fixed neighbourhoods of physical values of $\cos\theta$.