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Forward-Backward Correlations in Heavy Ion Collisions

Forward-Backward Correlations in Heavy Ion Collisions. Aaron Swindell, Morehouse College REU Cyclotron 2006, Texas A&M University Advisor: Dr. Che-Ming Ko. Quantum Chromodynamics (QCD). Utilized to strong interactions Standard model: Quarks and Gluons Color charge (Red, Blue, and Green)

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Forward-Backward Correlations in Heavy Ion Collisions

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  1. Forward-Backward Correlations in Heavy Ion Collisions Aaron Swindell, Morehouse College REU Cyclotron 2006, Texas A&M University Advisor: Dr. Che-Ming Ko

  2. Quantum Chromodynamics (QCD) • Utilized to strong interactions • Standard model: • Quarks and Gluons • Color charge (Red, Blue, and Green) • Six flavors (up, down, charm, strange, top, bottom) • SU(3) gauge group has 8 gauge bosons (gluon) • QCD Lagrangian • F=gluon field tensor • Ψ=Quark field • D=covariant derivative • Pertubative QCD • Running coupling: • Q=momentum transfer • asymptotic freedom • Length scale converges • Quark-Gluon Plasma

  3. QCD Matter (Quark Matter) • Phase Diagram http://www.pparc.ac.uk/frontiers/current/feature4.asp

  4. QCD Matter (cont.) • Experimental • Heavy-Ion Collisions (CERN, BNL, etc.) • Lorentz-contracted Nuclei • Hard Parton collisions/Jet Interactions • Parton Cascade/QGP • Hadron Phase

  5. Quark-Gluon Plasma (QGP) • Cosmic “soup” of almost-free quarks and gluons • Lattice-Gauge Theory • Used at low baryon densities & high temperatures • Predicts QGP transition at

  6. QGP (Experimental) • Collisions of large nuclei • Au+Au, Pb+Pb @ BNL & CERN • =200 GeV, 5.5 TeV respectively • “Fireball” • Main Observations • EM observables: photon(2-4 GeV) and dilepton enhancement • Strangeness: strangeness enhancement • Kinetic observable: elliptic flow • Hard probes: jet quenching, J/ψ suppression • Correlation: HBT Interferometry, fluctuations

  7. Theoretical Models • Thermal • Yield of various particles, ratios • Hydrodynamic • Behavior of low particles, elliptic flow • Transport • Treat chemical/thermal freeze-out dynamically • HBT Interferometry of hadrons

  8. A Multiphase Transport model (AMPT) • Describes collisions ranging from p+A to A+A systems • RHIC =200 GeV LHC (future) =5.5 TeV • HIJING (Heavy Ion Jet Interaction Generator) • Initial conditions • ZPC (Zhang’s Parton Cascade) • Lund string fragmentation/Quark coalescence • ART (ARelativistic Transport)

  9. AMPT (cont.) Default model (v1.11) String melting (v2.11)

  10. Forward-Backward Multiplicity Correlations using AMPT • Experimental collisions produce clusters of correlating partons • Au+Au collisions • = 200 GeV • 0-20% central • Event-wise observable (comparison) • Measure the variance

  11. Preliminary Data Nucl-ex/0603026

  12. Rapidity Distributions

  13. Variance

  14. Variance (cont.)

  15. Analysis • Evolution of hadrons in collisions is of much importance for fluctuations (the results from HIJING are much higher than from the AMPT model) • Partonic cascade and hadronic evolution have similar effects on fluctuations • The difference in magnitude between AMPT calculations and experimental data indicates that there may exist clusters of correlated particles in heavy ion collisions (clusters aren’t made in AMPT) L. J. Shi and S. Jeon, Phys. C72, 034904 (2005)

  16. Acknowledgements • Cyclotron Institute • Dr. Ko, Dr. Liu, Dr. Zhang • NSF • DOE • Fellow REU Participants

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