Semi-Hard Scattering Unraveled from Collective Dynamics by Two-Pion Azimuthal Correlations in 158 A GeV/c Pb + Au Collisions

Abstract

Elliptic flow and two-particle azimuthal correlations of charged hadrons and high-$p_T$ pions ($p_T>$ 1 GeV/$c$) have been measured close to mid-rapidity in 158A GeV/$c$ Pb+Au collisions by the CERES experiment. Elliptic flow ($v_2$) rises linearly with $p_T$ to a value of about 10% at 2 GeV/$c$. Beyond $p_T\approx$ 1.5 GeV/$c$, the slope decreases considerably, possibly indicating a saturation of $v_2$ at high $p_T$. Two-pion azimuthal anisotropies for $p_T>$ 1.2 GeV/$c$ exceed the elliptic flow values by about 60% in mid-central collisions. These non-flow contributions are attributed to near-side and back-to-back jet-like correlations, the latter exhibiting centrality dependent broadening.

Submitted to Phys. Rev. Letters, 4 pages, 5 figures

References in corpus (16)

• Methods for analyzing anisotropic flow in relativistic nuclear collisions
• Flow at the SPS and RHIC as a Quark Gluon Plasma Signature
• Disappearance of back-to-back high $p_T$ hadron correlations in central Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV
• Elliptic flow in Au+Au collisions at sqrt(s_NN) = 130 GeV
• Elliptic flow at SPS and RHIC: from kinetic transport to hydrodynamics
• Directed and elliptic flow of charged pions and protons in Pb+Pb collisions at 40 and 158A GeV
• Highly Sensitive Centrality Dependence of Elliptic Flow -- A Novel Signature of the Phase Transition in QCD
• Anisotropic flow
• Azimuthal anisotropy and correlations in the hard scattering regime at RHIC
• Observation of Anisotropic Event Shapes and Transverse Flow in Au+Au Collisions at AGS Energy
• Flow Measurements via Two-particle Azimuthal Correlations in Au + Au Collisions at sqrt(s_NN) = 130 GeV
• Beam Energy and Centrality Dependence of Two-Pion Bose-Einstein Correlations at SPS Energies
• Where is the jet quenching in Pb+Pb collisions at 158 AGeV?
• Effects of HBT correlations on flow measurements
• Flow and non-flow event anisotropies at the SPS
• Nuclear Broadening of Out-of-Plane Transverse Momentum in Di-Jet Production

Cited by in corpus (42)

• 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
• New Forms of QCD Matter Discovered at RHIC
• Hydrodynamic Models for Heavy Ion Collisions
• Perfect Fluidity of the Quark Gluon Plasma Core as Seen through its Dissipative Hadronic Corona
• Azimuthal anisotropy and correlations at large transverse momenta in $p+p$ and Au+Au collisions at $\sqrt{s_{{}_{NN}}}$= 200 GeV
• Mass, quark-number, and $\sqrt{s_{NN}}$ dependence of the second and fourth flow harmonics in ultra-relativistic nucleus-nucleus collisions
• Hydrodynamic afterburner for the Color Glass Condensate and the parton energy loss
• Early collective expansion: Relativistic hydrodynamics and the transport properties of QCD matter
• Azimuthally sensitive correlations in nucleus-nucleus collisions
• Indications of suppressed high p_T hadron production in nucleus-nucleus collisions at CERN-SPS
• Constraint fitting of experimental data with a jet quenching model embedded in a hydrodynamical bulk medium
• Saturation of azimuthal anisotropy in Au + Au collisions at sqrt(s_NN) = 62 - 200 GeV
• Elliptic flow contribution to two-particle correlations at different orientations to the reaction plane
• A local Monte Carlo framework for coherent QCD parton energy loss
• Non-Abelian Bremsstrahlung and Azimuthal Asymmetries in High Energy p+A Reactions
• Strangeness enhancements at central rapidity in 40 A GeV/c Pb-Pb collisions
• Causal Viscous Hydrodynamics for Relativistic Heavy Ion Collisions
• The QGP Discovered at RHIC
• Shear viscosity of the Quark-Gluon Plasma from a virial expansion
• Azimuthal dependence of pion source radii in Pb+Au collisions at 158 A GeV
• Elliptic flow of charged pions, protons and strange particles emitted in Pb+Au collisions at top SPS energy
• Blast-wave analysis of strange particle $m_T$ spectra in Pb-Pb collisions at the SPS
• Two particle azimuthal correlations at high transverse momentum in Pb-Au at 158 AGeV/c
• Proton-proton forward scattering at the LHC
• Hydrodynamic afterburner for the CGC at RHIC
• High pt Measurements at the CERN SPS
• Two- and three-particle azimuthal correlations of high-pt charged hadrons in Pb-Au collisions at 158A GeV/c
• Modification of jet-like correlations in Pb-Au collisions at 158A GeV/c
• Charge-multiplicity and collision-energy dependence of $p_t$ spectra from $p$-$p$ collisions at the relativistic heavy-ion collider and large hadron collider
• Has the Quark-Gluon Plasma been seen?
• Relativistic Nuclear Collisions and the QCD Phase Boundary
• Fermi motion and nuclear modification factor
• Two-particle azimuthal correlations at high transverse momentum in Pb-Au at 158 AGeV/c
• Semihard scattering unraveled from collective dynamics at $\sqrt{s}$=17 GeV
• From chemical freezeout to critical conditions in heavy ion collisions
• Recent high pT measurements in STAR
• Beam Energy Dependence of Azimuthal Anisotropy at RHIC-PHENIX
• Jet properties from ${\pi }^{\pm }$ - $h^{\pm }$ correlation in $p+p$ and $d$+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV
• The $v_3^{1/3}/v_2^{1/2}$ ratio in PbAu collisions at $\sqrt{s_{\mathrm{NN}}}=$ 17.3 GeV: a hint of a hydrodynamic behavior
• Modification of jet-like correlations in Pb-Au at the SPS
• Triangular flow of negative pions emitted in PbAu collisions at $\sqrt{s_{NN}}=$ 17.3 GeV