Unveiling the effects of multiple soft partonic interactions in pp collisions at s =13.6 TeV using a new event classifier

Abstract

Event classifiers based either on the charged-particle multiplicity or the event shape have been extensively used in proton-proton (pp) collisions by the ALICE Collaboration at the LHC. The use of these tools became very instrumental since the observation of fluidlike behavior in high-multiplicity pp collisions. In particular, the study as a function of the charged-particle multiplicity registered in the forward V0 ALICE detector allowed for the discovery of strangeness enhancement in high-multiplicity pp collisions. However, one drawback of the multiplicity-based event classifiers is that requiring a high charged-particle multiplicity biases the sample towards hard processes like multijet final states. These biases make it difficult to perform jet-quenching searches in high-multiplicity pp collisions. In this context, the present paper explores the use of the new event classifier, flattenicity

which uses the multiplicity calculated in the forward pseudorapidity region. To illustrate how this tool works, pp collisions at s=13.6 TeV simulated with pythia 8 are explored. The sensitivity of flattencity to multipartonic interactions as well as to the "hardness"of the collision are discussed. pythia 8 predictions for the transverse momentum spectra of light- and heavy-flavored hadrons as a function of flattenicity are presented. © 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.