1 / 71

Overview of Resonance Production

Investigating resonance production, widths, and masses in various particle collision experiments to understand collision dynamics. Examining different decay channels and their implications on the final collision stages.

deloresk
Download Presentation

Overview of Resonance Production

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related