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Patricia Fachini Brookhaven National Laboratory

Resonance Production. Recent Results. Patricia Fachini Brookhaven National Laboratory. Motivation Measurements Results Summary. π -. ρ 0. π +. ρ 0. ρ 0. ρ 0. π -. π +. π -. ρ 0. +. +. +. π +. -. -. -. Motivation - I.

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Patricia Fachini Brookhaven National Laboratory

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  1. Resonance Production Recent Results Patricia Fachini Brookhaven National Laboratory Motivation Measurements Results Summary QM2004, Oakland, Jan 11-17 Patricia Fachini

  2. π- ρ0 π+ ρ0 ρ0 ρ0 π- π+ π- ρ0 + + + π+ - - - Motivation - I • In-medium modification of mass and/or width  Chiral Symmetry Restoration, Collision Broadening or Phase Space? • ρ0(770) Leptonic decay channel probes all stages of the collision. Hadronic decay channel probes only late stages of the collision • Φ Information from early time ? • K*0(892)  Regeneration and daughter rescattering time scale ? ρ0 c = 1.3 fm Φ c = 44 fm QM2004, Oakland, Jan 11-17 Patricia Fachini

  3. π K* K K* measured π K* K*lost K π K* π π K* K K K K* measured Motivation - II • 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 • Λ*/Λ,Δ++/p,ρ0/π, f0/π? Chemical freeze-out Kinetic freeze-out QM2004, Oakland, Jan 11-17 Patricia Fachini

  4. σ(πp) σ(ππ) π p Δ++ π π p π Δ++ ρ π π π π π ρ π p π Δ++ K* π K π K* π π ρ K π π σ(Kπ) σ(ππ) Motivation - III • K*0 regeneration  σ(Kπ) • K*0daughter rescattering σ(ππ) • σ(ππ)>>>> σ(Kπ) • σ(pπ)>σ(ππ) • Hadronic cross-sections Change yields of K*,Λ*,Δ++,ρ0, f0 Chemical freeze-out Kinetic freeze-out  Probe dynamics between chemical and kinetic freeze-out QM2004, Oakland, Jan 11-17 Patricia Fachini

  5. Resonance Production – Hadronic Channel ρ0(770)π+ π-B.R. ~1 c = 1.3 fm Δ++(1232)  p π+ B.R. ~1 c = 1.6 fm f0(980) π+ π-B.R. 2/3 c = 2.6 fm K*0±(892) πK B.R. 2/3 c = 4 fm Σ(1385)  ΛπB.R. 0.88 c = 5.5 fm Λ(1520) p KB.R. 0.45 c = 12.6 fm Φ(1020) K+ K-B.R. 0.49 c = 44 fm Life Time QM2004, Oakland, Jan 11-17 Patricia Fachini

  6. Raw Invariant Mass Distribution from Data -I STAR Preliminary PHENIX NA49 Preliminary Minimum bias p+p ΦK+K- ΦK+K- Minimum bias Au+Au ΦK+K- 0-7% Pb+Pb sNN = 200 GeV sNN = 12.3 GeV |y|<0.5 |y|<2.0 STAR Preliminary NA49 Preliminary Minimum bias Au+Au ΦK+K- ΦK+K- sNN = 200 GeV 0-7% Pb+Pb Statistical error only |y|<0.5 sNN = 8.76 GeV Invariant Mass (GeV/c2) Invariant Mass (GeV/c2) Invariant Mass (GeV/c2) QM2004, Oakland, Jan 11-17 Patricia Fachini

  7. Σ*± +Σ*± Ξ+Ξ Raw Invariant Mass Distribution from Data -II STAR Preliminary STAR Preliminary Δ++ Δ++ 30-50% Au+Au Minimun bias p+p 0.8 ≤pT< 1.4 GeV/c 0.8 ≤pT< 1.3 GeV/c sNN = 200 GeV |y|<0.5 Statistical error only Invariant Mass (GeV/c2) Invariant Mass (GeV/c2) Λ(1520) Λ(1520) STAR Preliminary STAR Preliminary STAR Preliminary Minimun bias p+p Minimun bias p+p 0.4 ≤pT< 2.0 GeV/c 0-10% Au+Au 0.9 ≤pT< 1.5 GeV/c Invariant Mass (GeV/c2) Invariant Mass (GeV/c2) Invariant Mass (GeV/c2) QM2004, Oakland, Jan 11-17 Patricia Fachini

  8. Raw Invariant Mass Distribution from Data -III Minimun bias p+p 40-80% Au+Au 0.6 ≤pT< 08 GeV/c 0.6 ≤pT< 08 GeV/c STAR Preliminary sNN = 200 GeV STAR Preliminary |y|<0.5 Statistical error only STAR Preliminary STAR Preliminary STAR Preliminary K*± Minimun bias p+p Minimun bias p+p K*0 K*0 0-10% Au+Au 0.0 ≤pT< 3.2 GeV/c 0.8 ≤pT< 3.5 GeV/c 0.1 ≤pT< 1.5 GeV/c QM2004, Oakland, Jan 11-17 Patricia Fachini

  9. Phase Space = π+ ρ0 π+ π- π- -  M2 + pT2 M e T  M2 + pT2 3 Γ(M) Mρ M2– 4mπ2 2 BW(M) = Γ(M) = Γρ (M2 – M2)2+ M2Γ(M)2 Mρ2– 4mπ2 M Phase Space • M = Invariant Mass; pT = transverse momentum; T = Temperature • pp particle composition reasonably reproduced by statistical model  T = 160 MeV F. Becattini, Nucl. Phys. A 702, 336 (2002); Z. Phys. C 69, 485 (1996); F. Becattini and U. Heinz, Z. Phys. C 76, 269 (1997) • Au+Au between chemical and kinetic freeze-out  resonances formed until particles too far apart  resonances emittedT = 120 MeV E.V. Shuryak and G.E. Brown, Nucl. Phys. A 717 (2003) 322 P. Braun-Munzinger et.al., CERES Int. Note, March 2000, unpublished; E.V. Shuryak and G.E. Brown, Nucl. Phys. A 717 (2003) 322; P.K. Kolb and M. Prakash, nucl-th/0301007; H.W. Barz et al., Phys. Lett. B 265, 219 (1991); R. Rapp, hep-ph/0305011. QM2004, Oakland, Jan 11-17 Patricia Fachini

  10. K*0Mass and Width |y|<0.5 sNN = 200 GeV STAR Preliminary STAR Preliminary AuAu AuAu PDG value pp pp PDG value • K*0mass  shifted in p+p and Au+Au at low pT • K*0 width  agrees with the MC (GEANT) calculation • Systematic and statistical error added in quadrature QM2004, Oakland, Jan 11-17 Patricia Fachini

  11. Δ++Mass and Width |y|<0.5 sNN = 200 GeV STAR Preliminary STAR Preliminary Δ++ Mass GeV/c2 Δ++ Width GeV/c2 0.6 ≤ pT < 1.6 AuAu pp AuAu pp PDG value 0.6 ≤ pT < 1.6 pp dNch/dη dNch/dη • p+p at s = 27.5 GeV  MΔ++= 1225 ± 2 MeV/c2 • Δ++mass lower in p+p and Au+Au at low Nch • Δ++mass  increases with increasing Nch • Statistical errors only QM2004, Oakland, Jan 11-17 Patricia Fachini

  12. ρ0Mass • p+p at s = 27.5 GeV  M= 762.6 ± 2.6 MeV/c2 • PDG average hadroproduced ρ0 M= 769.0 ± 0.9 MeV/c2 • PDG average e+e-ρ M= 775.9 ± 0.5 MeV/c2 • ρ0mass ptdependent and lower than previous p+p measurement in both p+p and peripheral Au+Au collisions • ρ0mass high multiplicityp+plower than minimum bias p+p  multiplicity dependent • Systematic errors  common and correlated between p+p and peripheral Au+Au • ρ0width no sensitivity for systematic study 10% of minimum bias p+p for |η|<0.5 STAR Preliminary sNN = 200 GeV |y|<0.5 QM2004, Oakland, Jan 11-17 Patricia Fachini

  13. Possible Explanations for Mass Shift - I R. Rapp, hep-ph/0305011 • 1. Dynamical effectρ0interactions at late stages of the collision • nucleons, hyperons and baryon resonances • pions, kaons and ρ0-mesons • t-channel exchanges Distortion of the ρ0 spectral shape mass shift and/or broadening E.V. Shuryak and G.E. Brown, Nucl. Phys. A 717 (2003) 322 -23 MeV/c2 shift in the ρ0 mass -38 MeV/c2 shift in the ρ0mass due to t-channel attraction Δ++ different fromρ0 mass should increase!(prediction) QM2004, Oakland, Jan 11-17 Patricia Fachini

  14. π+ π+ π+ ρ0 ρ0 A A D π- π- π- Possible Explanations for Mass Shift - II • 2. Interference between various π+π- scattering channels can effectively distort the line shape of resonances R. Longacre, nucl-exp/0305015 • 3. Bose-Einstein correlations between ρ0decay daughters and pions in the surrounding matter can also distort the resonance shape G.D. Lafferty, Z. Phys. C 60, 659 (1993); R. Rapp, hep-ph/0305011; S. Pratt et al., nucl-th/0308087. Interference QM2004, Oakland, Jan 11-17 Patricia Fachini

  15. Spectra - I |y|<0.5 sNN = 200 GeV K*0 STAR Preliminary pp minbias ρ0 f0 K*± Au+Au Au+Au STAR Preliminary K*0 p+p STAR Preliminary p+p STAR Preliminary pp minbias Λ(1520) • Au+Au and K*0,Λ(1520)p+p spectra fit to exponential in mT-m0 • p+p  spectra fit to power-law Statistical error only QM2004, Oakland, Jan 11-17 Patricia Fachini

  16. Spectra - II sNN = 200 GeV NA49 Preliminary Δ++ Φ sNN = 200 GeV Au+Au Au+Au Φ |y|<0.5 p+p STAR Preliminary Central Pb+Pb p+p STAR Preliminary pp minbias Σ(1385) • Au+Au and Σ(1385)p+p  spectra fit to exponential • p+p  spectra fit to power-law sNN = 200 GeV Statistical error only QM2004, Oakland, Jan 11-17 Patricia Fachini

  17. Δ++ p ρ0 Φ π- K- K*0 K- Particle Ratios – Beam Energy Dependence STAR Preliminary STAR Preliminary STAR/NA49 Preliminary STAR Preliminary No strong energy and system size dependence (except K*0/K-) QM2004, Oakland, Jan 11-17 Patricia Fachini

  18. Particle Ratios – Multiplicity Dependence M. Bleicher et al. J. Phys. G 25 (1999) 1859 σ(Kπ) σ(ππ) Statistical and systematic errors added in quadrature σ(πp) • Φ/K-independent of centrality Φnot produced via kaon coalescence ? • Cross-section regeneration or rescattering ? QM2004, Oakland, Jan 11-17 Patricia Fachini

  19. t - c N(Δt) = N0 e K*0 K*0 K- K- 0.205 Au+Au = Δt - 0.385 c p+p e = Time between Chemical and Kinetic Freeze-out • If rescattering is the dominantprocess, • And the time between chemical and kinetic freeze-out should be Δt ~ 3 fm • If regeneration is the dominant process, Δt > 3 fm QM2004, Oakland, Jan 11-17 Patricia Fachini

  20. Δ++ p ρ0 π- K*0 K- Thermal Models - I Chemical freeze-out Au+Au Kinetic freeze-out Chemical = Kinetic freeze-out sNN = 200 GeV mρ=700MeV mρ=770MeV Statistical and systematic errors added in quadrature QM2004, Oakland, Jan 11-17 Patricia Fachini

  21. Λ(1520) Λ f0 π- Φ K- Thermal Models - II Chemical freeze-out sNN = 200 GeV Chemical freeze-out = Kinetic freeze-out Au+Au • Thermal calculations  Do not reproduce ratios of short-lived resonances Statistical and systematic errors added in quadrature QM2004, Oakland, Jan 11-17 Patricia Fachini

  22. Summary • Significantresonanceproduction measured from hadronic interactions • ρ0, K*0andΔ++mass shiftobserved in p+p and Au+Au collisions even after phase space correction • Δ++widthbroadening in central Au+Au collisions • Mass shift expected due to in-medium modifications, interference and Bose-Einstein correlations ? • Φ/K-independent of centrality Φnot produced via kaon coalescence ? • Short-lived resonances Regeneration and daughter rescattering driven by hadronic cross-sections ? • Resonancescan provide information on the collision dynamics QM2004, Oakland, Jan 11-17 Patricia Fachini

  23. PHENIX Preliminary Φe+e- dN/dy 1/2mT dN/dmTdy(GeV/c2)-2 ΦK+K- Minimum bias d+Au sNN = 200 GeV MT (GeV/c2) Outlook • What’s next? • We need: • Systematic study of K*0 and Δ++mass and widthin Au+Au • ρ0 in central Au+Au • Λ(1520),Σ(1385),Ξ(1530)… Other higher state resonances… • High-pTand v2 measurements of resonances • Leptonic Channel • Φ, ρ, ω… • Φ, ρComparison between leptonic and hadronic channels in Au+Au!!! • Requires • Large statistics RUN 4 @RHIC • RHIC Upgrades • Low mass dileptons  PHENIX • TOF  STAR QM2004, Oakland, Jan 11-17 Patricia Fachini

  24. Experimental References H. Zhangρ0(770), K*(892), Δ++(1232) STARPoster QM2004 S. SalurΣ(1385) STARPoster QM2004 C. Markert Λ(1520) STARTalk QM2004 J. MaΦ(1020)STAR Poster QM2004 L. Gaudiche Λ(1520) STARSQM2003 P. Fachinif0(980) STARSQM2003 R. SetoΦ(1020)PHENIX Talk QM2004 D. MukhpadhyayΦ(1020)PHENIX QM2002 C. MaguirreΦ(1020)PHENIX Poster QM2004 Marek Gazdzicki Φ(1020)NA49 Talk QM2004 V. Friese Φ(1020)NA49 SQM2003 QM2004, Oakland, Jan 11-17 Patricia Fachini

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