Investigating the most active pp collisions (top 0.1%) using the tools developed by experiments at the LHC

Abstract

The LHC data have unveiled unexpected features in proton-proton (pp) collisions, namely, collective-like behavior and strangeness enhancement. Originally, these new effects were discovered only in high-multiplicity pp collisions. However, recently the ALICE Collaboration has shown that even low-multiplicity pp collisions yield a non-zero elliptic flow ($v_2$). Moreover, analyses as functions of the event structure, such as transverse spherocity, suggest that multiplicity might not be the main driver of the new effects. Therefore, new ways of analyzing the data have to be explored in order to understand the origin of the new phenomena. In this paper, pp collisions simulated with PYTHIA 8 are analyzed using different event estimators (mid-pseudorapidity multiplicity, spherocity, sphericity, $R_T$, forward multiplicity and flattenicity). The features of the selected events for the top 0.1% using the different estimators are discussed. The transverse momentum spectrum of primary particles and the recoil jet distributions are analyzed. The results suggest that flattenicity is the estimator with the least bias on the neutral-to-charged particle ratio, and on the bias towards harder-than-average pp collisions.

14 pages, 8 figures

References in corpus (35)

• FastJet user manual
• Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC Collisions
• Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration
• Quark Gluon Plasma an Color Glass Condensate at RHIC? The perspective from the BRAHMS experiment
• The PHOBOS Perspective on Discoveries at RHIC
• Tuning PYTHIA 8.1: the Monash 2013 Tune
• Performance of the ALICE Experiment at the CERN LHC
• Observation of Long-Range Near-Side Angular Correlations in Proton-Proton Collisions at the LHC
• Enhanced production of multi-strange hadrons in high-multiplicity proton-proton collisions
• Parton distributions with QED corrections
• Glasma flux tubes and the near side ridge phenomenon at RHIC
• Initial state geometry and the role of hydrodynamics in proton-proton, proton-nucleus and deuteron-nucleus collisions
• Phenomenology of event shapes at hadron colliders
• The Angantyr model for Heavy-Ion Collisions in PYTHIA8
• Multiplicity dependence of light-flavor hadron production in pp collisions at $\sqrt{s}$ = 7 TeV
• The ALICE experiment: a journey through QCD
• Charged-particle production as a function of multiplicity and transverse spherocity in pp collisions at $\sqrt{s}$ = 5.02 and 13 TeV
• Transverse sphericity of primary charged particles in minimum bias proton-proton collisions at $\sqrt{s}=0.9$, 2.76 and 7 TeV
• Mid-rapidity charged hadron transverse spherocity in pp collisions simulated with Pythia
• First Measurement of Hadronic Event Shapes in pp Collisions at sqrt(s)=7 TeV
• Probing Collective Effects in Hadronisation with the Extremes of the Underlying Event
• Letter of intent for ALICE 3: A next-generation heavy-ion experiment at the LHC
• Measurement of charged-particle event shape variables in sqrt(s) = 7 TeV proton-proton interactions with the ATLAS detector
• Underlying Event properties in pp collisions at $\sqrt{s}$ = 13 TeV
• Unveiling the effects of multiple soft partonic interactions in pp collisions at $\sqrt{\text{s}}=13.6$ TeV using charged-particle flattenicity
• Apparent modification of the jet-like yield in proton-proton collisions with large underlying event
• Light-flavor particle production in high-multiplicity pp collisions at $\sqrt{\text{s}}=13$ TeV as a function of transverse spherocity
• Search for jet quenching effects in high-multiplicity pp collisions at $\sqrt{s}$ = 13 TeV via di-jet acoplanarity
• Production of pions, kaons, and protons as a function of the relative transverse activity classifier in pp collisions at $\sqrt{s}=13$ TeV
• Characterisation of plastic scintillator paddles and lightweight MWPCs for the MID subsystem of ALICE 3
• Particle production as a function of charged-particle flattenicity in pp collisions at $\sqrt{s}$ = 13 TeV
• Underlying-event properties in pp and p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV
• Fine structure in the azimuthal transverse momentum correlations at $\sqrt{s_{NN}}=200$ GeV using the event shape analysis
• Charged-particle production as a function of the relative transverse activity classifier in pp, p$-$Pb, and Pb$-$Pb collisions at the LHC
• ML-based muon identification using a FNAL-NICADD scintillator chamber for the MID subsystem of ALICE 3

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