PYTHIA82025/08/05 by Agarwala, Rohit, Dey, Kalyan
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Nuclear Theory (nucl-th)
paper · doi:10.48550/arxiv.2508.03124
We employ PYTHIA8 simulations to study forward-backward (FB) correlations in pp collisions at LHC energies, probing non-perturbative QCD dynamics via color reconnection (CR) and QCD radiation (ISR/FSR). Using PYTHIA8 (v8.311) under ALICE/ATLAS kinematics, we analyze: extensive: FB multiplicity (b\rm corr\rm mult) and summed p\rm T (b\rm corr^∑ p\rm T) correlations; intensive: FB mean p\rm T (b\rm corr^ p\rm T) correlations; and strongly intensive: Σ\rm NF NB quantity in symmetric pseudorapidity intervals, validated against available experimental data. Systematic studies of b\rm corr\rm mult as functions of η\rm gap, η\rm sep, and η-φ sectors show MPI-based CR (ranges 3.6, 5.4) and QCD Color Rope significantly improve agreement with data. ISR/FSR critically influence b\rm corr\rm mult and b\rm corr^∑ p\rm T, with ISR dominant than FSR. Disabling ISR/FSR fails to replicate η\rm gap-dependent trends. Further, b\rm corr^∑ p\rm T shows minimal CR-range sensitivity but the correlation strength increases when CR is disabled. Intensive quantity, b\rm corr^ p\rm T, exhibit the opposite behavior to extensive observables i.e. the magnitude of b\rm corr^ p\rm T increases with the increase of CR strength, highlighting the distinct influence of CR on intensive versus extensive observables. Its azimuthal dependence indicates that parton showers drive short-range correlations. The analysis of the strongly intensive quantity as a function of pseudorapidity gap indicates that FSR plays a dominant role at larger gaps, in contrast to the behavior observed in FB multiplicity correlations.