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Two-particle angular correlations in p+p and Cu+Cu at PHOBOS

Two-particle angular correlations in p+p and Cu+Cu at PHOBOS. Wei Li Massachusetts Institute of Technology for the Collaboration. 19th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2006), November 14-20, 2006, Shanghai, China.

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Two-particle angular correlations in p+p and Cu+Cu at PHOBOS

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  1. Two-particle angular correlations in p+p and Cu+Cu at PHOBOS Wei Li Massachusetts Institute of Technology for the Collaboration 19th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2006), November 14-20, 2006, Shanghai, China Wei Li, MIT

  2. Collaboration Burak Alver, Birger Back,Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Richard Bindel, Wit Busza (Spokesperson), Vasundhara Chetluru, Edmundo García, Tomasz Gburek, Joshua Hamblen, Conor Henderson, David Hofman, Richard Hollis, Roman Hołyński, Burt Holzman, Aneta Iordanova, Chia Ming Kuo, Wei Li, Willis Lin, Constantin Loizides, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Corey Reed, Christof Roland, Gunther Roland, Joe Sagerer, Peter Steinberg, George Stephans, Andrei Sukhanov, Marguerite Belt Tonjes, Adam Trzupek, Sergei Vaurynovich, Robin Verdier, Gábor Veres, Peter Walters, Edward Wenger, Frank Wolfs, Barbara Wosiek, Krzysztof Woźniak, Bolek Wysłouch ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORY INSTITUTE OF NUCLEAR PHYSICS PAN, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGY NATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGO UNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER 9 PhDs in progress！ Wei Li, MIT

  3. Outline • Introductions and motivations • Two-particle angular correlations in p+p • Two-particle angular correlations in Cu+Cu • Summary Wei Li, MIT

  4. Motivations PYTHIA p+p@200GeV -3<<3 (no weak decay) PHOBOS MC Two-particle correlation function 6 -6 Wei Li, MIT

  5. Motivations PYTHIA p+p@200GeV -3<<3 (no weak decay) No high pT trigger! PHOBOS MC Two-particle correlation function 6 -6 • All charged particles are included (soft physics) ! • Study particle correlations over a broad region -3<<3. • Shed light on the gross features of multi-particle production in p+p and A+A collisions. Wei Li, MIT

  6. Experimental setup PHOBOS apparatus Octagon Wei Li, MIT

  7. Experimental setup PHOBOS Octagon detector:  • Uniquely large acceptance: • -3<η<3 and almost full azimuthal angle . • Single-layer silicon detector: • No pT information, only (η,) of all charged particles. • Need corrections for secondary particles. • Holes for vertex detector and spectrometer: • Acceptance correction needed.  Wei Li, MIT

  8. Methodology Two-particle correlation function: Event 1 Foreground: ~ Background: Event 2 ~ Wei Li, MIT

  9. Two-particle correlations inp+p Wei Li, MIT

  10. Two-particle correlation function in p+p p+p@200GeV Foreground Background Wei Li, MIT

  11. Two-particle correlation function in p+p p+p@200GeV Foreground Background correlation function (uncorrected): Wei Li, MIT

  12. Two-particle correlation function in p+p p+p@200GeV Foreground Background correlation function (uncorrected): Secondary effects: -electron,  conversion etc. Wei Li, MIT

  13. Two-particle correlation function in p+p p+p@200GeV Two particle correlation function: Foreground Background correlation function (uncorrected): corrections by MC 6 Secondary effects: -electron,  conversion etc. -6 Wei Li, MIT

  14. Cluster model Isotropic cluster model: • Clusters are produced at the end of the collisions. • They are emitted independently. • They decay isotropically in their c.m.s into hadrons. C.Quigg, Phys. Rev. D 9, 2016 (1974) E. L. Berger, Nucl. Phys. B 85, 61 (1975).   Wei Li, MIT

  15. Cluster model Isotropic cluster model: • Clusters are produced at the end of the collisions. • They are emitted independently. • They decay isotropically in their c.m.s into hadrons. :clusters C.Quigg, Phys. Rev. D 9, 2016 (1974) E. L. Berger, Nucl. Phys. B 85, 61 (1975).         Wei Li, MIT

  16. Cluster model Isotropic cluster model: • Clusters are produced at the end of the collisions. • They are emitted independently. • They decay isotropically in their c.m.s into hadrons. :clusters C.Quigg, Phys. Rev. D 9, 2016 (1974) E. L. Berger, Nucl. Phys. B 85, 61 (1975).         Wei Li, MIT

  17. Cluster model Isotropic cluster model: • Clusters are produced at the end of the collisions. • They are emitted independently. • They decay isotropically in their c.m.s into hadrons. :clusters C.Quigg, Phys. Rev. D 9, 2016 (1974) E. L. Berger, Nucl. Phys. B 85, 61 (1975).         • Cluster model is a very generic model. • It is not clear whether it has any significance in QCD. • Or it is just a phenomenological description. Wei Li, MIT

  18. Cluster-like correlation structure higher pT clusters 6 lower pT clusters e.g. Resonance decay Wei Li, MIT -6

  19. Cluster-like correlation structure average over 6 -6 Wei Li, MIT

  20. Cluster-like correlation structure Two-particle rapidity correlation function:  average over scale error 6 -6 6  short-range rapidity correlations -6 Wei Li, MIT

  21. Parameterize cluster size (multiplicity) Quantitatively understand cluster phenomena Two-particle rapidity correlation function: K. Eggert et al., Nucl. Phys. B 86:201, 1975 Wei Li, MIT

  22. Parameterize cluster size (multiplicity) Quantitatively understand cluster phenomena correlations between particles from one cluster Two-particle rapidity correlation function: Decay width:  K. Eggert et al., Nucl. Phys. B 86:201, 1975 Wei Li, MIT

  23. Parameterize cluster size (multiplicity) Quantitatively understand cluster phenomena correlations between particles from one cluster Two-particle rapidity correlation function: Decay width:  K. Eggert et al., Nucl. Phys. B 86:201, 1975 k: cluster size Keff: effective cluster size Wei Li, MIT

  24. Parameterize cluster size (multiplicity) Quantitatively understand cluster phenomena correlations between particles from one cluster Two-particle rapidity correlation function: Decay width:  K. Eggert et al., Nucl. Phys. B 86:201, 1975 k: cluster size Keff: effective cluster size : background distribution Wei Li, MIT

  25. Cluster size and decay width scale error Wei Li, MIT

  26. Cluster size and decay width Scale error: 5% for Keff 4% for  (90% C.L.) Keff =2.44±0.08 =0.66 ±0.03 (90% C.L.) scale error Wei Li, MIT

  27. Cluster size and decay width Scale error: 5% for Keff 4% for  (90% C.L.) Keff =2.44±0.08 =0.66 ±0.03 (90% C.L.) On average, every charged particle is correlated with about another 1.5 particles! scale error Wei Li, MIT

  28. Clusters in p+p collisions Energy dependence of Keff and  PHOBOS preliminary p+p PHOBOS preliminary scale error Cluster size increases with energy! Wei Li, MIT

  29. Clusters in p+p collisions Energy dependence of Keff and  PHOBOS preliminary scale error UA5 HIJING ISR PYTHIA Cluster size increases with energy! Wei Li, MIT

  30. Clusters in p+p collisions Energy dependence of Keff and  PHOBOS preliminary scale error UA5 HIJING ISR PYTHIA Expected from resonances (UA5 collaboration) Cluster size increases with energy! Wei Li, MIT

  31. Clusters in p+p collisions Energy dependence of Keff and  PHOBOS preliminary scale error UA5 HIJING scale error ISR PYTHIA Expected from resonances (UA5 collaboration) Cluster size increases with energy! Wei Li, MIT

  32. Clusters in p+p collisions Multiplicity dependence of Keff and  410GeV 200GeV scale error scale error Cluster size increases with event multiplicity! Wei Li, MIT

  33. Clusters in p+p collisions Multiplicity dependence of Keff and  scale error scale error Cluster size increases with event multiplicity! Wei Li, MIT

  34. Two-particle correlations inCu+Cu Wei Li, MIT

  35. Two-particle correlations in Cu+Cu PHOBOS preliminary PHOBOS preliminary p+p@200GeV Cu+Cu@200GeV, 0%-10% 6 6 -6 -6 Wei Li, MIT

  36. Two-particle correlations in Cu+Cu PHOBOS preliminary PHOBOS preliminary p+p@200GeV Cu+Cu@200GeV, 0%-10% 6 6 -6 -6 Evolution of correlation structure from p+p to Cu+Cu: • Clear elliptic flow signals which extends to very high  in Cu+Cu. • Similar cluster-like structure as in p+p. Wei Li, MIT

  37. Two-particle correlations in Cu+Cu Cu+Cu@200GeV Wei Li, MIT

  38. Two-particle correlations in Cu+Cu Cu+Cu@200GeV Wei Li, MIT

  39. Two-particle correlations in Cu+Cu Cu+Cu@200GeV Wei Li, MIT

  40. Two-particle correlations in Cu+Cu Cu+Cu@200GeV Wei Li, MIT

  41. Two-particle correlations in Cu+Cu Cu+Cu@200GeV Wei Li, MIT

  42. Two-particle correlations in Cu+Cu Cu+Cu@200GeV More work will follow to subtract flow and study the medium effects on the correlation structures! Wei Li, MIT

  43. Cluster parameterization in Cu+Cu -5 5 Cu+Cu@200GeV -5 5 -5 5 Wei Li, MIT

  44. Cluster parameterization in Cu+Cu Scale error: 7% forKeff 8% for  (90% C.L.) Keff =2.76±0.11  =0.81±0.05 Kef f=2.89±0.14  =0.78±0.06 Keff =2.85±0.13  =0.80±0.06 (90% C.L.) (90% C.L.) (90% C.L.) -5 5 Kef f=2.49±0.12  =0.78±0.08 Keff= 2.19±0.12  = 0.74±0.06 (90% C.L.) (90% C.L.) Cu+Cu@200GeV Extract cluster parameters in Cu+Cu using two-particle rapidity correlation function -5 5 -5 5 Wei Li, MIT

  45. Clusters in Cu+Cu scale error Wei Li, MIT

  46. Clusters in Cu+Cu • To first order, cluster size • in Cu+Cu is similar to p+p. p+p scale error Wei Li, MIT

  47. Clusters in Cu+Cu • To first order, cluster size • in Cu+Cu is similar to p+p. • In Cu+Cu, cluster size • decreases with centrality. p+p scale error Wei Li, MIT

  48. Clusters in Cu+Cu • To first order, cluster size • in Cu+Cu is similar to p+p. • In Cu+Cu, cluster size • decreases with centrality. • Model comparison: • AMPT shows the same trend • but systematically lower in magnitude. • HIJING remains constant. p+p scale error Wei Li, MIT

  49. Clusters from Cu+Cu to Au+Au peripheral Phys. Rev. C74, 011901(R) (2006) =2 central Cu+Cu@200GeV Au+Au@200GeV • Cluster sizes from the two methods are similar in magnitude. • Cluster sizes decrease with centrality both in Cu+Cu and Au+Au. Wei Li, MIT

  50. Clusters from Cu+Cu to Au+Au peripheral Phys. Rev. C74, 011901(R) (2006) =2 central Cu+Cu@200GeV Au+Au@200GeV • Cluster sizes from the two methods are similar in magnitude. • Cluster sizes decrease with centrality both in Cu+Cu and Au+Au. Ongoing studies of two-particle correlations in Cu+Cu and Au+Au! Wei Li, MIT

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