Figure 6

Ratio of data or theory calculations to a fit of the neutral pion spectrum in pp collisions at $\snn =  2.76 {TeV}$. The renormalization, factorization, and fragmentation scale of the next-to-leading order QCD calculation were varied simultaneously ($\mu = 0.5 p_{\rm T}$, $p_{\rm T}$, $2 p_{\rm T}$). The calculation employed the CTEQ6M5 parton distribution functions and the DSS fragmentation function . The solid red line is a comparison to the PYTHIA 8.176 (tune 4C) event generator .