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Fragmentation and Recombination for Exotics in Heavy Ion Collisions

Explore fragmentation and recombination mechanisms in heavy ion collisions for exotic particles, focusing on baryon-meson differences, elliptic flow, and nuclear modification factors. Understand the transition from ReCo to fragmentation and the role of quark number scaling in elliptic flow. Investigate the ReCo + Fragmentation models and their impact on resonance particle production and hadron structure.

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Fragmentation and Recombination for Exotics in Heavy Ion Collisions

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  1. Fragmentation and Recombination for Exotics in Heavy Ion Collisions Chiho NONAKA Nagoya University May 21, 2010 @ExHIC10, Kyoto

  2. t collision thermalization hydrodynamic expansion hadronization freeze-out Hadronization Mechanism • Relativistic Heavy Ion Collision • Low PT • Thermal-statistical model:hadron ratios, chemical freezeout, P.Braun-Munsinger, PLB465,99 • Hydrodynamic expansion:PT spectra kinetic freezeout, Shnedermann,PRC48,93 • High PT • Perturbative QCD is applicable. • Fragmentation mechanism ?

  3. qq g : fragmentation functions Baryon Puzzle at RHIC • Large p/ ratio at high PT Fragmentation (PHENIX:nucl-ex/0307022) • p/p ratio ~ 1 (PT>2 GeV) • in central collisions • p/p ratio << 1

  4. hard scattering • in medium • jet quenching Baryon Puzzle at RHIC 2. Difference in baryon and meson jet-suppression Fragmentation • Parton energy loss at high PT • Suppression in RCPbaryon occurs at • higher PT than RCPmeson • RCPbaryon is the same as • RCPmeson.

  5. Baryon Puzzle at RHIC 3.Difference in baryon and meson elliptic flow Fragmentation parton energy lossL • Saturation in v2baryon occurs • at higher PT than v2meson. • v2baryon should be the same • as v2meson.

  6. Quark Number Scaling • Elliptic flow

  7. ReCo Models (RHIC) • ALCOR: Biro, Levai, Zimanyi, PLB347,6(1995), HIP17, 205(2003) • Dynamical model for hadronization • Duke:Fries, Nonaka, Bass, Asakawa, Mueller, PRL90,202303 (2003) • ReCo(thermal) + Fragmentation with energy loss No soft -hard ReCo • Texas:Greco, Ko, Levai, PRL90,202302(2003), PRC68,034904(2003) • Monte Carlo implementation • Soft (thermal/AMPT), hard (minijet) partons • Soft-hard ReCo • Resonance decay effect on v2, charm flow, v4, v6 • Ohio: Molnar, Lin, Voloshin, PRL90, 092301(2003),PRC68, 044901(2003) • Elliptic flow: quark number scaling, flavor ordering, charm hadrons • Oregon: Hwa,Yang, PRC67, 034902(2003),PRC67, 064902(2003) • Meson: Thermal-thermal, thermal-shower, shower-shower ReCo

  8. ReCo fragmenting parton: ph = z p, z<1 recombining partons: p1+p2=ph Frag. ReCo+Fragmentation Model Duke • Recombination at moderate PT • Recombination occurs • in an instant. • The parton spectrum is shifted to higher pT in the hadron spectrum. • Entropy and energy conservation • No gluon dynamics • Fragmentation at high PT • The parton spectrum has a power law tail (quarks and gluons) from pQCD. • The parton spectrum is shifted to lower pT in the hadron spectrum. PT>2GeV

  9. Meson: • ReCo up to ~3 GeV • Baryon: • ReCo up to ~5 GeV 2 4 6 8 10 12 PT(GeV) 2 4 6 8 10 PT(GeV) Hadron Spectra

  10. Hadron Ratios vs. PT R + F Statistical model • 2 < PT < 4~5 GeV ReCo • supports transition from • ReCo to fragmentation at intermediate • PT. baryon/meson~1 • 4 < PT < 6 GeV • steep drop: • transition from ReCo to fragmentation

  11. Nuclear Modification Factors Nuclear modification factor • 2 < PT < 4 GeV • RCP (baryon) > RCP (meson) • ReCo • 4 < PT < 6 GeV • steep drop • transition from ReCo to • fragmentation • High PT suppression • fragmentation R F R f ?

  12. Nuclear modification factor Velkovska(PHENIX)@QM2004 f Recombination mechanism works!

  13. Quark Number Scaling • Elliptic flow

  14. Quark Number Scaling elliptic flow of quarks elliptic flow of hadrons

  15. Elliptic Flow • v2 baryonsaturates at higher PT • at high PT: fragmentation • v2 baryon ~ v2meson Mesons meson • mass effect ? Hydrodynamical model • # of constituent quarks ? v2 ~ v2K Baryons PLB587,73(2004)

  16. v2 of  PHENIXPRL99(2007)052301 QM2005

  17. Elliptic Flow from fragmentation Fragmentation ReCo Frag. parton energy lossL • at high PT: fragmentation • v2 baryon ~ v2meson For resonances and exotics: universal v2 at high PT

  18. v2 for Resonance Particles n=2 scaling quarks n=4 scaling Total is determined by experiments and related to width of particles and cross section in the hadronic medium. • QGP resonances: • hadronizing QGP, no rescattering • HG resonances: • hadron final stage, h-h rescattering Final Interactions freeze-out process Key: v2 is additive for composite particles

  19. # of valence quarks K*0 Elliptic Flow (STAR) nucl-ex/0412019

  20. v2 for Exotics • Recombination: the same scaling for direct and molecule • Differences come from fragmentation mechanism

  21. v2 for Exotics 5 q state ReCo Frag. molecule (ReCo + Frag.) + (ReCo + Frag.)

  22. v2 for Exotics • Recombination: the same scaling for direct and molecule • Differences come from fragmentation mechanism • H dibaryon • heavy flavor, Lc, X, Y, Z, Tcc …? • thermalization, ReCo ? • universal v2 at high PT ? • v2 is measureable? • →yields, ratios

  23. Summary • elliptic flow analysis with ReCo + fragmentation model: useful tool of understanding of ・production process of resonance particles 　　　　・hadron structure ex. exotic particles

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