In a previous question, I asked about the apparent universality behaviour in hadron elastic scattering. I was particularly shocked to see that even $\gamma p$ showed that universal behaviour with respect the COM energy $s$. This can be seen in slides 35 and 36 in this presentation by Kazunori Itakura, Basics of Pomerons and Reggeons (NB: PDF)
As an explanation I received a vague statement about $\gamma$$\rho$ mixing which I do not understand. Could anybody try to explain and provide some references that I can study?
I apologize for asking over and over again, but it seems that Regge Theory is not a popular theory and I have nobody to ask when something puzzles me. Please believe me, I am totally uninterested in "reputation", "badges" and so on.
It is hard for me to believe that a photon is, in reality, a mixed state of a pure EM photon and a vector meson, as suggested in the comments. One of the referenced sources seems to indicate that it is just an effective model.
Could $\gamma\rho$ mixing be explained as a high energy renormalization effect induced by virtual quark-antiquark loops? This could be pure nonsense and I apologyze for it in advance in case it is.