Transverse sphericity of primary charged particles in minimum bias proton-proton collisions at $\sqrt{s}=0.9$, 2.76 and 7 TeV

Abstract

Measurements of the sphericity of primary charged particles in minimum bias proton--proton collisions at $\sqrt{s}=0.9$, 2.76 and 7 TeV with the ALICE detector at the LHC are presented. The observable is linearized to be collinear safe and is measured in the plane perpendicular to the beam direction using primary charged tracks with $p_{\mathrm{T}}\ge 0.5$ GeV/c in $|\eta |\le 0.8$. The mean sphericity as a function of the charged particle multiplicity at mid-rapidity ($N_{\mathrm{ch}}$) is reported for events with different $p_{\mathrm{T}}$ scales ("soft" and "hard") defined by the transverse momentum of the leading particle. In addition, the mean charged particle transverse momentum versus multiplicity is presented for the different event classes, and the sphericity distributions in bins of multiplicity are presented. The data are compared with calculations of standard Monte Carlo event generators. The transverse sphericity is found to grow with multiplicity at all collision energies, with a steeper rise at low $N_{\mathrm{ch}}$, whereas the event generators show the opposite tendency. The combined study of the sphericity and the mean $p_{\mathrm{T}}$ with multiplicity indicates that most of the tested event generators produce events with higher multiplicity by generating more back-to-back jets resulting in decreased sphericity (and isotropy). The PYTHIA6 generator with tune PERUGIA-2011 exhibits a noticeable improvement in describing the data, compared to the other tested generators.

21 pages, 9 captioned figures, 3 tables, authors from page 16, published version, figures from http://aliceinfo.cern.ch/ArtSubmission/node/3080

References in corpus (3)

• Hadron production in p+p, p+Pb, and Pb+Pb collisions with the HIJING 2.0 model at energies available at the CERN Large Hadron Collider
• Search for Randall-Sundrum Gravitons in the Diphoton Channel at CDF
• Measurement of Event Shapes in Proton-Antiproton Collisions at Center-of-Mass Energy 1.96 TeV

Cited by in corpus (49)

• Color reconnection and flow-like patterns in pp collisions
• Multiplicity dependence of the average transverse momentum in pp, p-Pb, and Pb-Pb collisions at the LHC
• Multiplicity dependence of charged pion, kaon, and (anti)proton production at large transverse momentum in p-Pb collisions at $\sqrt{{\text{s}}_{\mathrm{NN}}}$ = 5.02 TeV
• Charged-particle multiplicities in proton-proton collisions at $\sqrt{s}$ = 0.9 to 8 TeV
• Experimental evidence for an attractive p-$\varphi$ interaction
• Event-by-event mean $p_{\mathrm{T}}$ fluctuations in pp and Pb-Pb collisions at the LHC
• Charged-particle production as a function of multiplicity and transverse spherocity in pp collisions at $\sqrt{s}$ = 5.02 and 13 TeV
• Scattering studies with low-energy kaon-proton femtoscopy in proton-proton collisions at the LHC
• Mid-rapidity charged hadron transverse spherocity in pp collisions simulated with Pythia
• Constraining the $\overline{\mathrm{K}}\mathrm{N}$ coupled channel dynamics using femtoscopic correlations at the LHC
• Multiplicity dependence of two-particle azimuthal correlations in pp collisions at the LHC
• Jet and underlying event properties as a function of particle multiplicity in proton-proton collisions at sqrt(s) = 7 TeV
• Intriguing similarities between high-$p_{\mathrm{T}}$ particle production in pp and A-A collisions
• Universality of the underlying event in pp collisions
• Investigation into the event-activity dependence of ${\rm Y}$(nS) relative production in proton-proton collisions at $\sqrt{s}=$ 7 TeV
• Probing color reconnection with underlying event observables at the LHC energies
• Measurement of charged-particle event shape variables in sqrt(s) = 7 TeV proton-proton interactions with the ATLAS detector
• Heavy-ion physics at the LHC: Review of Run I results
• Event Shape Engineering and Multiplicity dependent Study of Identified Particle Production in proton+proton Collisions at $\sqrt{s}$= 13 TeV using PYTHIA8
• Novel model for particle emission in small collision systems
• Unveiling the effects of multiple soft partonic interactions in pp collisions at $\sqrt{\text{s}}=13.6$ TeV using charged-particle flattenicity
• Measurement of hadronic event shapes in high-$p_{\text{T}}$ multijet final states at $\sqrt{s}=13$ TeV with the ATLAS detector
• Event-shape and multiplicity dependence of freeze-out radii in pp collisions at $\sqrt{\text{s}}=7$ TeV
• Mean pt scaling with m/nq at the LHC: Absence of (hydro) flow in small systems?
• Event shape variables measured using multijet final states in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Noether Symmetries of a Modified Model in Teleparallel Gravity and a New Approach for Exact Solutions
• Universal geometrical scaling for hadronic interactions
• $J/\psi$ Production Dynamics: Event shape, Multiplicity and Rapidity dependence in Proton+Proton Collisions at LHC energies using PYTHIA8
• ${\mathrm{K}}^{\ast }(892{)}^0$ and $\varphi (1020)$ production in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV
• Electroweak, QCD and flavour physics studies with ATLAS data from Run 2 of the LHC
• Dark side of the universe in the Stephani cosmology
• Overview of ALICE results
• Extraction of the multiplicity dependence of Multiparton Interactions from LHC pp data using Machine Learning techniques
• Energy dependence of underlying-event observables from RHIC to LHC energies
• Effects produced by multi-parton interactions and color reconnection in small systems
• Event shapes and jets in $e^{+}{e}^{-}$ and pp collisions
• Femtoscopic correlations of identical charged pions and kaons in pp collisions at $\sqrt{s}=13$ TeV with event-shape selection
• Particle production as a function of charged-particle flattenicity in pp collisions at $\sqrt{s}$ = 13 TeV
• Probing strangeness with event topology classifiers in pp collisions at energies available at the CERN Large Hadron Collider with the rope hadronization mechanism in PYTHIA
• Investigating the p-${\pi }^{\pm }$ and p-p-${\pi }^{\pm }$ dynamics with femtoscopy in pp collisions at $\sqrt{s}=13$ TeV
• Strange particle production in jets and underlying events in pp collisions at $\sqrt{s}=7$ TeV with PYTHIA8 generator
• Optimizing the parton shower model in PYTHIA with pp collision data at $\sqrt{s}$ = 13 TeV
• Multiple Parton Interactions with ALICE: from pp to p-Pb
• Soft QCD Physics at the LHC: highlights and opportunities
• Investigating the most active pp collisions (top 0.1%) using the tools developed by experiments at the LHC
• Soft-QCD physics in pp and p-Pb with ALICE
• Measurement of event shapes in minimum-bias events from proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Intrinsic coupling between transverse spherocity and elliptic flow in heavy-ion collisions
• Review of recent results on heavy-ion physics and astroparticle physics in ALICE at the LHC