Investigating the non-flow effects of long-lived stable hadrons in proton+proton collisions at LHC energies using PYTHIA8

Abstract

Traditionally proton+proton (pp) collision was considered to be the baseline in measurement for heavy-ion collisions. However, recent stud ies at the LHC suggest hints of collectivitiy in small systems, in tandem with strangeness enhancement and ridge-like structure at high multiplic ity pp events. This indicates towards the possible formation of a medium even in small systems like that is produced in pp collisions. During ultra relativisitc heavy-ion collisions, the system achieves a very large energy density (ϵc > 1 GeV/fm3) and high temperature (150-170 MeV, which is 105 hotter than the core of the sun), as a result of which quarks and gluons undergo multiple interactions. These interactions leads to a collective expansion and cooling of particles before they eventually hadronize. This expansion is called “flow”. However, this characteristic signal is not only generated by flow; there are also contributions that can mimic flow-like effects. These are referred to as “non-flow”. In small collision systems, these non-flow effects are more dominant than in large collision systems (e.g.,lead+lead (Pb+Pb), gold+gold (Au+Au). Thus non-flow effects in small systems needs to be studied in detail to have a better understanding of the dynamics of the system, With this moti vation, in this work we have investigated the contribution of non-flow effects in pp system by long-lived hadrons at √s = 13 TeVand 7 TeV using pQCD inspired model (PYTHIA8). We have extracted elliptic flow by virtue of non-flow effects and relative associated yield to have an idea about medium effects in pp system.