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Overview of Resonance Production

Overview of Resonance Production. P. Fachini Brookhaven National Laboratory. Motivation Measured Resonances Masses and Widths Spectra and Yields Ratios Outlook. Motivation. π -. ρ 0. π +. ρ 0. ρ 0. ρ 0. π -. π +. π -. ρ 0. +. +. +. π +. -. -. -. Motivation - I.

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Overview of Resonance Production

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  1. Overview of Resonance Production P. Fachini Brookhaven National Laboratory Patricia Fachini

  2. Motivation Measured Resonances Masses and Widths Spectra and Yields Ratios Outlook Patricia Fachini

  3. Motivation Patricia Fachini

  4. π- ρ0 π+ ρ0 ρ0 ρ0 π- π+ π- ρ0 + + + π+ - - - Motivation - I • Medium modification of mass and/or width  Chiral Symmetry Restoration, Collision Broadening and/or Phase Space? • ρ0leptonic decay channel probes all stages of the collision R. Rapp and J. Wambach, Adv. Nucl. Phys. 25, 1 (2000); G. E. Brown and M. Rho, Phys. Rev. Let. 66 2720 (1991); P. Braun-Munzinger, GSI Internal Report ρ0 c = 1.3 fm • ρ0hadronic decay channel probes latestages of the collision Patricia Fachini

  5. Motivation - II • Φ information early stages of the collision • Φ  modification mass shape and width • Φ  different production for hadronic and leptonic channels • Nucleon-nucleon collisions  η, ω and ρ0 at high pT  perturbative QCD • A+A collisions  η, ω and ρ0at high pT  nuclear effects can modify particle production • Δ++ mass and width modification in medium • K*  time between chemical and kinetic freeze-out Φ c = 44 fm S. Pal et al., Nucl.Phys. A707 (2002) 525-539 RHIC Δ++ Hees and Rapp Hot Quarks04 Hees and Rapp, HotQuarks04 Patricia Fachini

  6. π K* K K* measured π K* K*lost K π K* π π K* K K K K* measured Motivation - III • If resonance decays before kinetic freeze-out  not reconstructed due to rescattering of daughters • K*0(c = 4 fm)survival probability timebetween chemical and kinetic freeze-out, source size and pT of K*0 • Chemical freeze-out elastic interactionsπK  K*0 πKregenerate K*0(892)until kinetic freeze-out • K*0/K may reveal time between chemical and kinetic freeze-out Chemical freeze-out Kinetic freeze-out Patricia Fachini

  7. Measured Resonances Patricia Fachini

  8. Resonance Production ρ0(770)π+ π-B.R. ~1 c = 1.3 fm Δ++(1232)  p π+ B.R. ~1 c = 1.6 fm K*(892) πK B.R. ~1 c = 4 fm Σ(1385)  ΛπB.R. 0.88 c = 5.5 fm Λ(1520) p KB.R. 0.45 c = 12.6 fm Ξ(1530) ΞπB.R. ~1 c = 21 fm ω(782) π+ π-π0B.R. 0.89 c = 23 fm ω(782) π0 B.R. 0.089 c = 23 fm Φ(1020) K+ K-B.R. 0.49 c = 44 fm Φ(1020) e+e-B.R. 0.000296 c = 44 fm η(547) π+ π-π0B.R. 0.23 c = 167225 fm Life Time Patricia Fachini

  9. Δ++(1232)  p π+ B.R. ~1 c = 1.6 fm STAR Preliminary STAR Preliminary √sNN = 200 GeV √sNN = 200 GeV Patricia Fachini

  10. K*(892) πK B.R. ~1 c = 4 fm STAR Preliminary STAR Preliminary √sNN = 200 GeV √sNN = 200 GeV √sNN = 62 GeV STAR Preliminary Patricia Fachini

  11. Σ(1385)  ΛπB.R. 0.88 c = 5.5 fm Λ(1520) p KB.R. 0.45 c = 12.6 fm Ξ(1530) ΞπB.R. ~1 c = 21 fm Ξ* STAR Preliminary Au+Au √sNN = 200 GeV √sNN = 200 GeV STAR Preliminary Λ* Minimum Bias d+Au STAR Preliminary Patricia Fachini

  12. ω(782) π+ π-π0B.R. 0.89 c = 23 fm ω(782) π0 B.R. 0.089 c = 23 fm η(547) π+ π-π0B.R. 0.23 c = 167225 fm p+p Au+Au PHENIX η,ω π+π-π0 p+p ω π0 ω π0 PHENIX PHENIX √sNN = 200 GeV Patricia Fachini

  13. Φ(1020) K+ K-B.R. 0.49 c = 44 fm Φ(1020) e+e-B.R. 0.000296 c = 44 fm d+Au PHENIX Φ K+K- STAR Preliminary √sNN = 200 GeV Au+Au PHENIX Φ e+e- √sNN = 200 GeV Patricia Fachini

  14. Sub-Threshold Measurements K(892) (< 800 MeV) Σ(1385) (< 400 MeV) K*0 K+ + - Σ*±  + ± Al+Al 1.9 AGeV FOPI Al+Al 1.9 AGeV FOPI Patricia Fachini

  15. K0Sπ+π- ω(782) (π+π-) π0and π+ π- K0S ω η (π+π-) π0 and (π+π-) η’ (π+π-)ηand (π+π-) ρ0 η + η’ K*(892)0 Kπwith K misidentified as π K*0 + K*0misidentified π+π- Invariant Mass Distribution from Monte Carlo • HIJING events with a realistic simulation of detector response STAR Preliminary ρ0(770)  π+π- sNN= 200 GeV ρ0 • Use ωandK*0shape from HIJING to fit the data • K*0signal is fixed using STAR measurement Patricia Fachini

  16. ρ0(770)π+ π-B.R. ~1 c = 1.3 fm STAR Preliminary STAR Preliminary 20-40% dAu 0.6 ≤ pT < 0.8 GeV/c 40-100% dAu 0.6 ≤ pT < 0.8 GeV/c √sNN = 200 GeV √sNN = 200 GeV STAR Preliminary STAR Preliminary 40-80% Au+Au 0.6 ≤ pT < 0.8 GeV/c 0-20% dAu 0.6 ≤ pT < 0.8 GeV/c √sNN = 62 GeV √sNN = 200 GeV Patricia Fachini

  17. Masses and Widths Patricia Fachini

  18. K*  Mass and Width STAR Preliminary • K*0 pT < 1 GeV mass shift of ~10 MeV observed • K*± and K*0 pT > 1 GeV  mass agrees with PDG for all systems within errors • Width agrees with PDG for all systems within errors • Systematic error shown for minimum bias d+Au 200 GeV MC PDG K*0 PDG K*± PDG STAR Preliminary Patricia Fachini

  19. Δ++  Mass and Width PDG • Δ++ mass shift observed in both minimum bias p+p and d+Au at √sNN = 200 GeV • Width agrees with PDG for both systems within errors PDG Patricia Fachini

  20. ω  Mass • Nomass shift observed in both minimum bias p+p and d+Au at √sNN = 200 GeV • Statistical error shown fit PDG fit PDG Patricia Fachini

  21. ρ0  Mass • Mass shift observed for all systems • Towards the vacuum value at high pT? • Systematic errors shown for Minimum Bias d+Au 200 GeV STAR Preliminary Patricia Fachini

  22. STAR ρ0 Hadronic channel  STAR (RHIC) • Probing late of the collisions • Mass shift ~70 MeV Patricia Fachini

  23. ρ0  Dimuons channel  NA60 (SPS) Hees and Rapp, hep-ph/0603084 • Probing all stages of the collisions • Mass broadening Patricia Fachini

  24. STAR Mass Shift in A+A Hees and Rapp, hep-ph/0603084 SPS RHIC • ~70 MeV mass shift measured by STAR in peripheral Au+Au collisions and no apparent broadening • Broadening measured by NA60 in central In-In collisions and no mass shift • Are these measurements in agreement? • RHIC di-lepton measurements! Patricia Fachini

  25. ρ0Mass at High-PT Patricia Fachini

  26. ρ0  Mass at High pT • η production fixed according to PHENIX data • K0s production fixed according to STAR data • ρ0 mass = 775.9 MeV fixed • ρ0 width = 160 MeV fixed • f0mass = 980 MeV fixed • f0width = 100 MeV fixed • f2mass = 1275 MeV fixed • f2width = 185 MeV fixed • In p+pω and ρ0 production are assumed to be the same Patricia Fachini

  27. ρ0  Mass at High pT STAR Preliminary • ρ0mass at high pT pure relativistic BW function • ρ0 mass at high pT equivalent measurement e+e- • Mass shift observed at low pT is not a detector effect! Background STAR Preliminary p+p 200GeV Central Au+Au 200GeV STAR Preliminary Phys. Rev. Lett. 92 (2004) 092301 Minimum Bias Au+Au 200GeV Patricia Fachini

  28. Masses and Widths • No mass or width modification of η, ω, Φ, Λ*, Σ* or Ξ* • Mass shift observed for K*, Δ++ and ρ0 at low-pT  possible explanations • π+π- rescattering in p+p collisions • Medium modifications • Bose-Einstein correlations • ρ0 at high-pT No apparent mass shift! P. Fachini et.al., J.Phys.G33:431-440,2007 R. Rapp, Nucl.Phys. A725, 254 (2003), E.V. Shuryak and G.E. Brown, Nucl. Phys. A 717 (2003) 322 G.D. Lafferty, Z. Phys. C 60, 659 (1993); R. Rapp, Nucl.Phys. A725 (2003) 254-268 S. Pratt et al., Phys.Rev. C68 (2003) 064905 Patricia Fachini

  29. Spectra Patricia Fachini

  30. Spectra-I STAR Preliminary STAR Preliminary Patricia Fachini

  31. Spectra-II K*0 Au+Au √sNN = 62 GeV STAR Preliminary STAR Preliminary √sNN = 200 GeV Patricia Fachini

  32. Spectra-III Φ K+ K- STAR Preliminary STAR Preliminary STAR Preliminary Patricia Fachini

  33. Spectra-IV Au+Au 62 GeV Patricia Fachini

  34. ΦProduction K+K- and e+e- e+e- K+K- • The leptonic channel yield is a little higher than hadronic channel • More accurate measurement is required to confirm whether there is branch ratio modification Patricia Fachini

  35. Φ Production K+K- J. Rafelski et al.,Phys.Rev. C72 (2005) 024905 STAR • Φ production  there is a factor of ~2 difference between PHENIX and STAR! • BRAHMS measurement agrees with STAR at midrapidity PHENIX STAR +PHENIX √sNN = 200 GeV Patricia Fachini

  36. Ratios Patricia Fachini

  37. Φ Ratios STAR Preliminary • Φ/K- independent of centrality • UrQMD does not reproduce data  kaon coalescence not the main production mechanism for Φ! • Φ/K- reproduced by thermal models  no rescattering (or regeneration) due to c= 44 fm Patricia Fachini

  38. Resonance to stable particle ratios √sNN = 200 GeV c = 1.3 fm c = 4 fm c = 1.6 fm • ρ0,Δ++andΣ* ratios independent of centrality or system size • K* andΛ*  suppression compared to p+p collisions c = 12.6 fm c = 5.5 fm STAR Preliminary Patricia Fachini

  39. t - c N(Δt) = N0 e 0.23 Au+Au = 0.35 K*0 K*0 p+p K- K- Δt - c e = Time between freeze-outs • If rescattering is the dominantprocess, • And the time between chemical and kinetic freeze-out should be Δt = 2 ± 1 fm • If no regeneration is present Δt = 2 ± 1 fm • Blast-Wave fit to π±, K±, p, and p  Δt > 6 fm Patricia Fachini

  40. K*  Ratios STAR Preliminary Statistical errors only • K*/K- ratio in central collisions at 62 GeV and 200 GeV are comparable same time between chemical and kinetic freeze-outs Patricia Fachini

  41. η, ω and ρ0 Ratios η STAR Preliminary • ω/π0 ratio constant for pT> 2 GeV  lower than PYTHIA  ω/π0= 1.0 • ρ0/π-ratio constant for 5 < pT < 10 GeV  lower than PYTHIA • η/π0ratio  comparable to PYTHIA • ω/π0and ρ0/π-measuredcomparable √sNN = 200 GeV ρ0π+π- Patricia Fachini

  42. Ratios • Φ/K- independent and constant for all collision systems kaon coalescence not the main production mechanism for Φ! • Φ/K- reproduced by thermal models  no rescattering (or regeneration) due to c = 44 fm • ρ0,Δ++andΣ* ratios independent of centrality • K* andΛ* suppression compared to p+p collisions • K*/K- ratio in central collisions at 62 GeV and 200 GeV are comparable same time between chemical and kinetic freeze-outs • ρ0/π-ratio constant for 5 < pT < 10 GeV  lower than PYTHIA • ω/π0and ρ0/π0measuredcomparable Patricia Fachini

  43. Outlook • What’s next? • We need: • Systematic study of K*0 and Δ++mass and widthin Au+Au (RUN4) • ρ0 in central Au+Au  overwhelming combinatory background • ρ0 in central Cu+Cu  doable… • Λ(1520),Σ(1385),Ξ(1530)… Other higher state resonances… • High-pTand v2 measurements of resonances • a1  γπ±  e+e-π± • Leptonic Channel • Φ, ρComparison between leptonic and hadronic channels in A+A!!! • Requires • Large statistics • RHIC Upgrades • Low mass dileptons  PHENIX (HBD) and STAR (TOF) • TOF full coverage  STAR Patricia Fachini

  44. Backup Slides Patricia Fachini

  45. Φ  Mass and Width STAR Preliminary • pT > 1 GeV  mass and width agree with MC and PDG for all systems • pT < 1 GeV  mass agrees with MC for all systems within errors • pT < 1 GeV  width higher than MC for all systems  real physics or detector effect? • No significant mass or width modification observed PDG STAR Preliminary PDG Patricia Fachini

  46. an v2(pT,n) = - dn 1 + exp[-(pT/n – b)/c] Elliptic Flow - I • KS0 and Λv2 scale number constituent quarks  v2/n • Resonance v2 • πK  K* n = 4 • qq  K* n = 2 • Significant K*0v2 measured • Fitting K*0 v2to a, b, c, and d constants extracted using KS0and Λ v2 • K*0 v2n= 2.0 ± 0.3 C. Nonaka et al., Phys.Rev. C69 (2004) 031902 X. Dong et al., Phys.Lett. B597 (2004) 328 Minimum Bias Au+Au 200GeV STAR Preliminary Patricia Fachini

  47. Elliptic Flow - II • Significant Φ v2 measured • v2 increases with decreasing centrality • Φnot produced via kaon coalescence  Φinformation fromearly stagesnon-zeroΦv2 s-quarks flow Partonic collectivity • Intermediate pTΦ v2 consistent with KS0than Λ  favors NCQ=2  Recombination/ Coalescence models • Φ v2n= 2.3 ± 0.4 Au+Au 200GeV Patricia Fachini

  48. Elliptic Flow • s-quarks flow as u- and d-quarks • Φ not produced via kaon coalescence and do not participate strongly in hadronic interactions  evidence for partonic collectivity! • Φ and K*  intermediate pT formed via quark-quark coalescence Patricia Fachini

  49. Nuclear Modification Factor • K*(892) andΦ mesons • K*(892) and Φ mass closer to Λ mass • K* and ΦRCP intermediate pT closer to KS0than Λ evidence for baryon/meson effect  favors parton recombination Patricia Fachini

  50. STAR Φ Ratios Chemical freeze-out Chemical = Kinetic freeze-out • Φ/K- ratio reproduced by thermal model  Φ has long lifetime!not affected by rescattering (or regeneration) Patricia Fachini

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