I'm having some difficulty finding some clear data on the relationship of the average mass of emitted particles in collision experiments with respect to the center-of-mass energy. My understanding is that the average mass does generally increase with energy but due to parton saturation and perhaps other effects, heavier particles are less favored in these highly-dense conditions. This seems to suggest that as $\sqrt{s}$ increases, the contribution of the rapidity to the momentum of outgoing particles would increasingly dominate the contribution of their mass. Or am I missing something here?
Bonus for any references to data on this. Thanks!