Disentanglement of hard and soft QCD processes using two-particle correlation functions

Abstract

Transverse spherocity (S 0) has evolved as a powerful method to distinguish between soft and hard contributions in an event in small collision systems. We used the two-particle differential-number correlation functions (R 2) and transverse momentum correlation functions (P 2) of charged particles produced in pp collisions at TeV with the PYTHIA8 model to explore this phenomena. The Δφ projections of these correlation functions in different multiplicity and S 0 classes are discussed. We find that these correlation functions show different shapes and sizes in both near- and away-side with multiplicity and S 0 classes. We observe a strong correlation in the near- and away-side of these correlation functions for jetty-like (hard QCD processes), which become weaker for isotropic (soft QCD processes) in spherocity classes as compared to multiplicity classes. Finally, it is observed that S 0 should be a good observable as compared to multiplicity to disentangle hard and soft QCD processes in a small collision system.