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Identified Di-hadron Correlation in Au+Au & PYTHIA Simulation

CCAST Beijing,. Identified Di-hadron Correlation in Au+Au & PYTHIA Simulation. Jiaxu Zuo Shanghai Institute of Applied Physics & BNL. Outline. Motivation Results & Discussions Correlation in PYTHIA Summary. leading particle. hadrons. q. q. hadrons. leading particle.

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Identified Di-hadron Correlation in Au+Au & PYTHIA Simulation

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  1. CCAST Beijing, Identified Di-hadron Correlation in Au+Au & PYTHIA Simulation Jiaxu Zuo Shanghai Institute of Applied Physics & BNL

  2. Outline • Motivation • Results & Discussions • Correlation in PYTHIA • Summary

  3. leading particle hadrons q q hadrons leading particle Leading particle suppressed hadrons q q hadrons p+p collision Au+Au collision leading particle suppressed Jet in p+p & Au+Au • Jet • p+p collisions, the hard scattering of quarks and gluons • Jet quenching: • The hard jet loses a significant amount of its energy via radiating gluon induced by multiple scattering.

  4. pT,trig>2.5 GeV/c pT,ass>1.0 GeV/c 0.6 0.4 0.2 0.0 STAR preliminary Di-hadron correlations pT,trig>4 GeV/c pT,ass>2 GeV/c For high pT: away-side correlation is gone! back-to-back jets are quenched At lower pT: away-side correlations return but they are highly modified with a double bump!? We will try to understand what causes this behavior

  5. Centrality dependence M. Horner, QM06 pT,trig>2.5 GeV/c pT,ass>1.0 GeV/c Singly-peaked -> broadened -> becomes doubly bump What’s the baryon/meson ratio in the near- and away-side peak? What are the anti-baryon-to-baryon ratios? We will measure the ratios to try to understand the source of the correlations in different centralities.

  6. B/M Ratio Intermediate pT STAR preliminary large enhancement of baryon/meson ratio in central Au+Au relative to p+p reaches maximum at pT~3 GeV/c Perhaps related to faster increase with centrality of baryon production from recombination Intermediate pT, Baryon & Meson: Grouping of RCP and v2 ----recombination pictures Can recombination explain particle ratios in the jet cones?

  7. Anti-B/B Ratio Intermediate pT STAR preliminary We can also learn about gluons vs quarks from B/B ratios with the jet correlation. For example: anti-baryons  dominated by gluon jets baryons  mixture of quark and gluon

  8. STAR preliminary Anti-Baryon Density H.D.Liu QM06 • Collisions which containggg, qbar+g or qqbar+gprocesses have higher anti-baryon phase space density • Anti-baryon phase space density from collisions involving a gluon is much higher than those without a gluon H. Liu, Z. Xu nucl-ex/0610035 • From B/B ratios in the correlation • Baryon & Anti-baryon production with Jets • Gluon vs. Quarks with Jets

  9. Quark jet Gluon jet Gluon Jets Vs. Quark Jets • PYTHIA in the correlation • Quark jets & Gluon jets in the correlation • Correlation particle ratio in the PYTHIA with different jets • Baryon & Meson in the correlation STAR, Phys Lett B, 637 (2006) 161 • PYTHIA: • gluon jets: baryon-meson splitting • quark jets: mass splitting. • STAR data: • baryon-meson splitting • predicts a slight dependence forL/L dominated by the gluon jet events.

  10. away-side associated Λ, Λ, K0S parton parton near-side associated trigger hadron Λ, Λ, K0S Trigger-associate correlations • Identified particles correlations & B/M , B/B ratio can provide additional information on: • jet quenching • baryon/meson enhancement at STAR • particle production mechanisms • Di-hadron correlation Away-side shape • We’ll study identified associate particles using • Trigger: Charged hadron, pT>3.0 GeV/c • Associate:KS0, , or (i.e. V0 decay), pT>1.0 GeV/c

  11. Hadron_Ks & L+L Correlation 3<pT,trig<6 GeV/c 1<pT,ass<4 GeV/c • Centrality bin: 10-40% • The yellow band : systematic error • From the line: Left part: near-side Right part: away-side Near-Side Away-Side

  12. Hadron_L &L Correlation 3<pT,trig<6 GeV/c 1<pT,ass<4 GeV/c Centrality bin: 10-40% • The yellow band: Systematic error. • From the line: Left part: near-side Right part: away-side Near-Side Away-Side

  13. C. Nattrass QM2008 STAR Preliminary Baryon to Meson Ratio with Jets • Lambda to Ks Ratio : Away-Side > Near-Side • Anti-Proton to p-Ratio : Away-Side > Near-Side (PHENIX) • Away-Side ~ Au+Au Near-Side ~ p+p • B/M ratio in Near-Side & Away-Side: |Dh|<1.0 • Away-Side > Near-Side • Near-Side: Au+Au ~ p+p • Away-Side ~ inclusive • B/M ratio in Jet and Ridge: • Jet ~ p+p • Ridge ~ inclusive in Au+Au

  14. 3<pT,trig<6 GeV/c 1<pT,ass<4 GeV/c 3<pT,trig<6 GeV/c 1<pT,ass<4 GeV/c B/M & Bbar/B Ratio with Jets • B/M ratio: • Near-side : independent with the Npart • Away-side: increase with the Npart  parton density increase • Bbar/B ratio: • Near-side and Away-side seems consistent. • Also seems independent with the Npart with in the errors.

  15. pT,trig>2.5 GeV/c pT,ass>1.0 GeV/c near 0.6 0.4 0.2 Medium away mach cone 0.0 STAR preliminary near Medium away deflected jets The shape of the ratio • Mach Cone Concept/Calculations • Stoecker, Casalderry-Solana et al; Muller et al.; Ruppert et al., … • Cherenkov RadiationMajumder, Koch, & Wang; Vitev • Jet Deflection (Flow) • Fries; Armesto et al.; Hwa • Strong Parton Interaction • G.L. Ma, S. Zhang M. Horner, QM06 • Can we learn something about the shape on the away-side? • For our pT range slower particles would have to be heavy • For production from sound wave excitation the bumps should have mostly heavy particles (+)/KS0 would get large in the bump region

  16. near Medium mach cone away Δ = p/2 Trigger Associate Δ=p Medium B/M Ratio in DFDistribution • B/M ratio: Away-Side seems to increase in the "cone" region - as it maybe for sound wave excitation. • Increased B/M ratio may also be consistent with recombination in high density region of the shock-wave • Error bars too large to get strong conclusions • The same shape in the away-side using v2 background from three different methods • The shape of Baryon to Meson ratio on the away-side seems to be independent of v2 background and background subtraction method. • Perhaps a slope , but error bars are still too large to draw conclusions. L+L/KS0

  17. Preliminary Results Preliminary Results Identified Correlation in PYTHIA • Correlation function: • particle dependence • Clearly away-side peak ~ p+p data in STAR • Quark & Gluon Jet: • gluon jet > quark jet Quark jet: pp->qq Gluon jet: pp->gg

  18. Preliminary Results Preliminary Results Identified Correlation in PYTHIA • Pbar/pion Ratio • Near-Side > Away-Side • Gluon jet ~ ee->ggg • Quark jet ~ ee->qqbar • Gluon jet > Quark jet • Anti-Lambda/Lambda Ratio • Almost consistent with STAR data • Gluon jet: Near < Away • Quark jet: Away > Near • Quark jet > Gluon jet

  19. Summary • Measured the Conditional Yields of identified associate particles on the near- and away-side of jets • Extracted particle ratios on the near and away-side • Away-Side ~ Au+Au • Near-Side ~ p+p • B/M ratio: • Near-side : independent with the Npart • Away-side: increase with the Npart => parton density increase • Shape of away-side has been studied • some indication of a slope for B/M on the away-side (mach-cone? gluon vs. quark? Or others?) • slope of B/M on the away-side seems to be independent of v2 and background subtraction method • Di-Hadron in PYTHIA • Correlation Conditional yields: gluon jet > quark jet • Particle ratios with jet => energy loss in the gluon & quark anti-baryon production with jet strangeness production with jet Thanks!!

  20. Backup

  21. Correlation Physics • Hard scatterings in p+p collisions produce back-to-back "jets" of particles • In nuclear collisions, jets instead serve as a penetrating probe of the extremely dense nuclear matter • Comparing characteristics of jets in nuclear collisions to jets in p+p collisions has uncovered special properties of dense nuclear matter. • Azimuthal correlations

  22. Ratio vs.Df • B/B Ratio at Near-Side • B/B Ratio vs.Df at Away-Side • B/M Ratio at Near-Side • B/M Ratio vs.Df at Away-Side

  23. Preliminary Results STAR Data Strange particle ratio with Jet • Anti-B/B Ratio • Pbar/p: • Near > Away • Near: gluon jet ~ quark jet ~ 1.0 • Away: gluon jet > quark jet • Gluon jet: Near ~ Away • Lbar/L: • RatioLbar/L > Ratiopbar/p • Near > Away • Quark jet > Gluon jet • Gluon jet: Near < Away • Energy loss: gluon & quark • Strangeness production: gluon & quark

  24. Particle Ratio with Correlation • Jet like p+p • Ridge like bulk • Away-Side ~ Ridge • B/M ratio in Near-Side & Away-Side: |Dh|<1.0 • Away-Side > Near-Side • Near-Side: Au+Au ~ p+p • Away-Side ~ inclusive • B/M ratio in Jet and Ridge: • Jet ~ p+p • Ridge ~ inclusive in Au+Au

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