Jet-like correlations with neutral pion triggers in pp and central Pb-Pb collisions at 2.76 TeV

Abstract

We present measurements of two-particle correlations with neutral pion trigger particles of transverse momenta $8<p_{\mathrm{T}}^{\mathrm{trig}}<16\mathrm{GeV}/c$ and associated charged particles of $0.5<p_{\mathrm{T}}^{\mathrm{assoc}}<10\mathrm{GeV}/c$ versus the azimuthal angle difference $\Delta \phi$ at midrapidity in pp and central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV with ALICE. The new measurements exploit associated charged hadrons down to $0.5\mathrm{GeV}/c$, which significantly extends our previous measurement that only used charged hadrons above $3\mathrm{GeV}/c$. After subtracting the contributions of the flow background, $v_2$ to $v_5$, the per-trigger yields are extracted for $|\Delta \phi |<0.7$ on the near and for $|\Delta \phi -\pi |<1.1$ on the away side. The ratio of per-trigger yields in Pb--Pb to those in pp collisions, $I_{\mathrm{AA}}$, is measured on the near and away side for the $0$--$10$\% most central Pb--Pb collisions. On the away side, the per-trigger yields in Pb--Pb are strongly suppressed to the level of $I_{\mathrm{AA}}\approx 0.6$ for $p_{\mathrm{T}}^{\mathrm{assoc}}>3\mathrm{GeV}/c$, while with decreasing momenta an enhancement develops reaching about $5$ at low $p_{\mathrm{T}}^{\mathrm{assoc}}$. On the near side, an enhancement of $I_{\mathrm{AA}}$ between $1.2$ at the highest to $1.8$ at the lowest $p_{\mathrm{T}}^{\mathrm{assoc}}$ is observed. The data are compared to parton-energy-loss predictions of the JEWEL and AMPT event generators, as well as to a perturbative QCD calculation with medium-modified fragmentation functions. All calculations qualitatively describe the away-side suppression at high $p_{\mathrm{T}}^{\mathrm{assoc}}$. Only AMPT captures the enhancement at low $p_{\mathrm{T}}^{\mathrm{assoc}}$, both on the near and away side. However, it also underpredicts $I_{\mathrm{AA}}$ above $5$ GeV/$c$, in particular on the near-side.

arXiv comment26 pages, 5 captioned figures, 1 table, authors from page 20, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/3021

References in corpus (73)

• PYTHIA 6.4 Physics and Manual
• PYTHIA 6.2 Physics and 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
• A Multi-Phase Transport Model for Relativistic Heavy Ion Collisions
• Suppression of Hadrons with Large Transverse Momentum in Central Au+Au Collisions at $sqrt {s sub {sub {NN}}}_ = 130 GeV
• Performance of the ALICE Experiment at the CERN LHC
• Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV
• Observation of a Centrality-Dependent Dijet Asymmetry in Lead-Lead Collisions at sqrt(S(NN))= 2.76 TeV with the ATLAS Detector at the LHC
• Multiple Collisions and Induced Gluon Bremsstrahlung in QCD
• Transverse momentum and collision energy dependence of high $p_T$ hadron suppression in Au+Au collisions at ultrarelativistic energies
• Observation and studies of jet quenching in PbPb collisions at nucleon-nucleon center-of-mass energy = 2.76 TeV
• Disappearance of back-to-back high $p_T$ hadron correlations in central Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV
• Evidence from d+Au measurements for final-state suppression of high $p_T$ hadrons in Au+Au collisions at RHIC
• Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at 2.76 TeV
• Centrality dependence of high pT hadron suppression in Au+Au collisions at sqrt(sNN)=130 GeV
• Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV
• Study of high-pT charged particle suppression in PbPb compared to pp collisions at sqrt(sNN)=2.76 TeV
• Extracting jet transport coefficient from jet quenching at RHIC and LHC
• Centrality determination of Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV with ALICE
• Triangular flow in hydrodynamics and transport theory
• High-p_T Tomography of d+Au and Au+Au at SPS, RHIC, and LHC
• Dihadron azimuthal correlations in Au+Au collisions at sqrt(s_NN)=200 GeV
• The LPM effect in QCD and Radiative energy loss in a quark-gluon plasma
• Transverse Momentum Spectra in Au+Au and d+Au Collisions at $\sqrt{s_{NN}}$=200 GeV and the Pseudorapidity Dependence of High p${}_T$ Suppression
• Measurement of the pseudorapidity and transverse momentum dependence of the elliptic flow of charged particles in lead-lead collisions at sqrt(s_NN) = 2.76 TeV with the ATLAS detector
• Modifications to Di-Jet Hadron Pair Correlations in Au+Au Collisions at sqrt(s_NN) = 200 GeV
• Centrality dependence of dihadron correlations and azimuthal anisotropy harmonics in PbPb collisions at sqrt(s[NN]) = 2.76 TeV
• Jet momentum dependence of jet quenching in PbPb collisions at sqrt(sNN)=2.76 TeV
• Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
• Direct observation of dijets in central Au+Au collisions at sqrt(s_NN) = 200 GeV
• Harmonic decomposition of two-particle angular correlations in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Studies of jet quenching using isolated-photon + jet correlations in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV
• Measurement of the distributions of event-by-event flow harmonics in lead--lead collisions at sqrt(s_NN)=2.76 TeV with the ATLAS detector at the LHC
• Systematic Study of High p_T Hadron Spectra in pp, pA and AA Collisions from SPS to RHIC Energies
• Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV
• Measurements of the Nuclear Modification Factor for Jets in Pb+Pb Collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV with the ATLAS Detector
• Modification of jet shapes in PbPb collisions at sqrt(s[NN]) = 2.76 TeV
• Evidence for transverse momentum and pseudorapidity dependent event plane fluctuations in PbPb and pPb collisions
• Measurement of jet fragmentation in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV
• A perturbative framework for jet quenching
• Measurement of jet suppression in central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Dihadron Tomography of High-Energy Nuclear Collisions in NLO pQCD
• Measurement of higher-order harmonic azimuthal anisotropy in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV
• Measurement of inclusive jet charged-particle fragmentation functions in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV with the ATLAS detector
• Charged hadron transverse momentum distributions in Au+Au collisions at sqrt(s_NN) = 200 GeV
• Cherenkov Radiation from Jets in Heavy-ion Collisions
• Measurement of charged-particle spectra in Pb+Pb collisions at $\sqrt{s_{\mathsf{NN}}}=2.76$ TeV with the ATLAS detector at the LHC
• Dependence on pseudorapidity and centrality of charged hadron production in PbPb collisions at a nucleon-nucleon centre-of-mass energy of 2.76 TeV
• Measurement of jet fragmentation into charged particles in pp and PbPb collisions at sqrt(s[NN]) = 2.76 TeV
• Cronin Effect in Hadron Production off Nuclei
• Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV in a multiphase transport model
• Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Collisional energy loss of a fast heavy quark in a quark-gluon plasma
• Quantitative Constraints on the Transport Properties of Hot Partonic Matter from Semi-Inclusive Single High Transverse Momentum Pion Suppression in Au+Au collisions at sqrt(s_NN) = 200 GeV
• Large Angle Hadron Correlations from Medium-Induced Gluon Radiation
• Jets, Mach cone, hot spots, ridges, harmonic flow, dihadron and $\gamma$-hadron correlation in high-energy heavy-ion collisions
• Evidence of b-jet quenching in PbPb collisions at sqrt(s[NN]) = 2.76 TeV
• Centrality Dependence of the High p_T Charged Hadron Suppression in Au+Au collisions at sqrt(s_NN) = 130 GeV
• Transverse momentum and centrality dependence of dihadron correlations in Au+Au collisions at sqrt(s_NN)=200 GeV: Jet-quenching and the response of partonic matter
• Trends in Yield and Azimuthal Shape Modification in Dihadron Correlations in Relativistic Heavy Ion Collisions
• The QCD collisional energy loss revised
• System Size and Energy Dependence of Jet-Induced Hadron Pair Correlation Shapes in Cu+Cu and Au+Au Collisions at sqrt(s_NN) = 200 and 62.4 GeV
• Jet Shapes in Opaque Media
• Jet-like Correlations with Direct-Photon and Neutral-Pion Triggers at $\sqrt{s_{{}_{NN}}}=200$ GeV
• Medium modification of jet fragmentation in Au+Au collisions at sqrt(s_NN)=200 GeV measured in direct photon-hadron correlations
• Suppression of high transverse momenta hadrons in Pb+Pb collisions at LHC
• Away-side azimuthal distribution in a Markovian parton scattering model
• Quantifying jet transport properties via large $p_T$ hadron production
• Hydrodynamic Flow from Fast Particles
• Correction methods for finite-acceptance effects in two-particle correlation analyses

Cited by in corpus (17)

• K${}^{\ast }(892{)}^0$ and $\varphi (1020)$ meson production at high transverse momentum in pp and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Constraints on jet quenching in p-Pb collisions at $\sqrt{{\mathbf{s}}_{\mathbf{NN}}}$ = 5.02 TeV measured by the event-activity dependence of semi-inclusive hadron-jet distributions
• Measurement of inclusive charged-particle jet production in Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV
• Information field based global Bayesian inference of the jet transport coefficient
• Extracting jet transport coefficient via single hadron and dihadron productions in high-energy heavy-ion collisions
• Measurement of the inclusive isolated photon production cross section in pp collisions at $\sqrt{s}$ = 7 TeV
• Anomalous evolution of the near-side jet peak shape in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Performance of the ALICE Electromagnetic Calorimeter
• Evolution of the longitudinal and azimuthal structure of the near-side jet peak in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV
• Study of charged particle production at high $p_{\mathrm{T}}$ using event topology in pp, p$-$Pb and Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV
• Jet-hadron correlations measured relative to the second order event plane in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Jet modification via ${\pi }^0$-hadron correlations in Au$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV
• Jet-like correlations with respect to K${}_{\mathrm{S}}^0$ and $\Lambda$ ($\bar{\Lambda }$) in pp and central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
• Measurement of away-side broadening with self-subtraction of flow in Au+Au collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=200$ GeV
• Investigating $\Lambda$ baryon production in p-Pb collisions in jets and the underlying event using angular correlations
• Latest results from RHIC + Progress on determining $\hat{q}L$ in RHI collisions using di-hadron correlations
• Neutral meson production and correlation with charged hadrons in pp and Pb-Pb collisions with the ALICE experiment at the LHC