Energy Scaling of Minimum-Bias Tunes

Abstract

We propose that the flexibility offered by modern event-generator tuning tools allows for more than just obtaining "best fits" to a collection of data. In particular, we argue that the universality of the underlying physics model can be tested by performing several, mutually independent, optimizations of the generator parameters in different physical regions. For regions in which these optimizations return similar and self-consistent parameter values, the model can be considered universal. Deviations from this behavior can be associated with a breakdown of the modeling, with the nature of the deviations giving clues as to the nature of the breakdown. We apply this procedure to study the energy scaling of a class of minimum-bias models based on multiple parton interactions (MPI) and pT-ordered showers, implemented in the Pythia 6.4 generator. We find that a parameter controlling the strength of color reconnections in the final state is the most important source of non-universality in this model.

17 pages, 3 figures, 4 tables

References in corpus (5)

• PYTHIA 6.4 Physics and Manual
• Parton Distributions for LO Generators
• Systematic event generator tuning for the LHC
• Non-perturbative QCD Effects and the Top Mass at the Tevatron
• Charged-particle multiplicities in pp interactions at sqrt(s) = 900 GeV measured with the ATLAS detector at the LHC

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• Novel Collective Phenomena in High-Energy Proton-Proton and Proton-Nucleus Collisions
• Multiplicity dependence of the average transverse momentum in pp, p-Pb, and Pb-Pb collisions at the LHC
• MCPLOTS: a particle physics resource based on volunteer computing
• Introduction to QCD
• Measurement of dijet azimuthal decorrelations in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector and determination of the strong coupling
• The Development of MPI Modelling in PYTHIA
• Measurement of the ratio of three-jet to two-jet cross sections in pp-bar collisions at sqrt(s) = 1.96 TeV
• A new quantity for studies of dijet azimuthal decorrelations
• Average Event Properties from LHC to FCC-hh
• Transverse Momentum Distributions of Identified Particles in p-Pb Collisions at $\sqrt{{\mathrm{s}}_{\mathrm{NN}}}=5.02\mathrm{TeV}$