Ratio of $b_{corr}$ at 2.76 (blue squares) and 7 TeV (red circles) with respect to 0.9 TeV vs. $\eta_{\rm gap}$ The calculations from MC generators are also shown: PYTHIA Perugia 0 (solid line), Perugia 2011 (dotted line) and PHOJET (dashed line), for 2.76 TeV (blue lines) and 7 TeV (red lines).