A Detailed Comparison of NLO QCD Evolution Codes
J. Blümlein, M. Botje, C. Pascaud, S. Riemersma, W. L. van Neerven, A. Vogt, F. Zomer
TL;DR
The paper conducts a meticulous comparison of seven NLO QCD evolution codes to quantify how different truncation prescriptions of the perturbative series affect predictions for parton densities and the structure function F2. It contrasts x-space and Mellin-N approaches, identifies NNLO truncation as a major source of discrepancies, and through targeted code refinements achieves agreement better than 0.1% across a wide kinematic range for five codes. Two sets of reference results are provided to enable precise future benchmarking. The work improves confidence in NLO evolution for high-precision QCD analyses, essential for extracting parameters like alpha_s from HERA data.
Abstract
Seven next-to-leading order QCD evolution programs are compared. The deviations of the results due to different theoretical prescriptions for truncating the perturbative series are clarified, and a numerical agreement between five codes of better than 0.1% is achieved. Reference results for further comparison are provided.