QCD saturation at the LHC: comparisons of models to p+p and A+A data and predictions for p+Pb collisions
Prithwish Tribedy, Raju Venugopalan
TL;DR
This paper extends a CGC-based kt-factorization framework, constrained by HERA data, to compare saturation-model predictions with p+p, A+A, and p+A data at RHIC and LHC and to forecast p+Pb collisions. It shows that IP-Sat and rcBK saturation models describe bulk observables like multiplicity distributions and pseudorapidity spectra across collision systems, with running coupling improving high-energy behavior and centrality trends. The results support a picture where initial-state gluon saturation and Glasma flux tubes influence particle production, while residual discrepancies in peripheral A+A point to additional final-state entropy production. The work provides clear RpA predictions for LHC p+A and guides interpretation of upcoming p+Pb measurements.
Abstract
In a previous paper (arXiv:1011.1895), we showed that saturation models, constrained by e+p HERA data on inclusive and diffractive cross-sections, are in good agreement with p+p data at LHC in the soft sector. Particularly impressive was the agreement of saturation models with the multiplicity distribution as a function of $n_{\rm ch.}$. In this paper, we extend these studies further and consider the agreement of these models with data on bulk distributions in A+A collisions. We compare our results to data on central and forward particle production in d+Au collisions at RHIC and make predictions for inclusive distributions in p+Pb collisions at the LHC.