  We discuss scattering in a CFT via the conformal partial-wave analysis and
the Regge limit. The focus of this paper is on understanding an OPE with
Minkowski conformal blocks. Starting with a t-channel OPE, it leads to an
expansion for an s-channel scattering amplitude in terms of t-channel
exchanges. By contrasting with Euclidean conformal blocks we see a precise
relationship between conformal blocks in the two limits without preforming an
explicit analytic continuation. We discuss a generic feature for a CFT
correlation function having singular $F^{(M)}(u,v)\sim {u}^{-\delta}\,$,
$\delta>0$, in the limit $u \rightarrow 0$ and $v\rightarrow 1$. Here,
$\delta=(\ell_{eff}-1)/2$, with $\ell_{eff}$ serving as an effective spin and
it can be determined through an OPE. In particular, it is bounded from above,
$\ell_{eff} \leq 2$, for all CFTs with a gravity dual, and it can be associated
with string modes interpolating the graviton in AdS. This singularity is
historically referred to as the Pomeron. This bound is nearly saturated by
SYK-like effective $d=1$ CFT, and its stringy and thermal corrections have
piqued current interests. Our analysis has been facilitated by dealing with
Wightman functions. We provide a direct treatment in diagonalizing dynamical
equations via harmonic analysis over physical scattering regions. As an example
these methods are applied to the SYK model.
