Flattenicity as centrality estimator in p–Pb collisions simulated with PYTHIA/Angantyr

Abstract In this paper, a centrality estimator based on flattenicity is studied using PYTHIA 8.312 Angantyr, whose existing implementation is enough to study the particle production in p–Pb collisions in the absence of medium effects. The number of binary nucleon–nucleon collisions for different centrality estimators are compared. The studies include forward multiplicity, forward flattenicity and midrapidity multiplicity. The results using flattenicity show the smallest deviations (<8%) with respect to the results which use impact parameter for centrality classes. On the other hand, the multiplicity-based estimators exhibit huge deviations (up to a factor 2) with respect to the results using impact parameter. The particle ratios (proton-to-pion and kaon-to-pion ratios) and nuclear modification factors as a function of p T are also studied for the different centrality estimators. The studies presented here are relevant to help in the investigation of the plethora of effects, which have been reported by experiments at the Large Hadron Collider.