particle physics - Do the proton PDFs change much with Q?

Specifically, the second moments, do they change much from say 100 to 1000 GeV? Why or why not?

Answer

You can check directly yourself using the Durham HEPData page, which lets you plot PDFs as a function of $x$ or $Q^2$.

At large $x = 0.1$, they're fairly constant over a range of $Q^2$.

But at small $x = 10^{-4}$, they rise quickly with $Q^2$:

This is an illustration of Bjorken scaling at large $x$ and its breaking at small $x$.

I'd also mention that the $Q^2$-dependence of the PDFs is predicted from QCD by the DGLAP equations, so you can look at those to further understand the behavior.