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Measurement of the light mesons with the PHENIX experiment at RHIC

Measurement of the light mesons with the PHENIX experiment at RHIC. Victor Riabov for the Collaboration. Outline. What do we learn from light mesons ( , K, ,  ) PHENIX experimental capabilities Analyzed decays Detectors and triggers

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Measurement of the light mesons with the PHENIX experiment at RHIC

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  1. Measurement of the light mesons with the PHENIX experiment at RHIC Victor Riabov for the Collaboration Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  2. Outline • What do we learn from light mesons (, K,, ) • PHENIX experimental capabilities • Analyzed decays • Detectors and triggers • Experimental conditions and background • Results: • Spectra and cross checks • Integrated yields • Particle ratios • Nuclear modification factors RAB • Mass Peak Shape • Summary Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  3. Motivation • In p+p: • Test of pQCD at large momentum transfer (parton distribution and fragmentation functions) • Strangeness content of the event (K,) • Non-identical particle ratios (heavier mesons to 0) • Reference for heavy ion collisions • In Heavy Ions collisions: • Nuclear modification factors, high pT suppression, Cronin effect • An insight at the Chiral Symmetry Restoration (ω,) • line-shape analysis • particle yields in hadron and di-electron decay channels Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  4. Analyzed decays   K+K-BR = 49.2  0.7%   e+e-BR = 2.97 0.04%   e+e-BR = 7.18 0.12%  0BR = 8.90  0.25%   0+-BR = 89.1  0.7%    BR = 39.39  0.24%   0+-BR = 22.68  0.35% KS  00BR = 30.69  0.05% K±using ToF PHENIX acceptance : -0.35 < h < 0.35 2 x 90o for two arms BBC (vertex) dz = 0.5cm… 2cm BBC (trigger) ε = 50%… 92% DC/PC1 (tracking) dpT/pT ~ 1.0%•pT + 0.7% EMC (calorimetric) dE/E ~ 8.1%/√E + 3.0% EMC (t.o.f.) dτ ~ 500 ns EMC (e/π rejection) ~10 EMC (γ-trigger) 0.4GeV… 2.5GeV PC3 (matching) 2-4 mm TOF dτ ~ 100 ns RICH (e/π rejection) >1000 Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  5. Triggers Gamma Final meson • Minimum bias • EMC-RICH electron trigger • High pT gamma trigger Due to many particles in the final state of hadron decays even very high pT are affected by the efficiency rising region. Comparison to minimum bias trigger sample at low and intermediate pT is very important PRC75 (2007) 024909 Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  6.  - meson decay modes p+p d+Au Au+Au hadronic   e+e-Au+Au √sNN=200 GeV   e+e-d+Au √sNN=200 GeV   e+e-p+p √sNN=200 GeV Analysis is not complete  leptonic    K+K- p+p √sNN=200 GeV   K+K-d+Au √sNN=200 GeV   K+K-Au+Au √sNN=200 GeV PHENIX measures clear signal of K+K- in all collision systems Measurement of e+e- is complicated by combinatorial background Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  7.  - meson decay modes p+p d+Au Au+Au 0Au+Au √sNN=200 GeV hadronic ω e+e-d+Au √sNN=200 GeV ω e+e-Au+Au √sNN=200 GeV Analysis ω is not ω complete leptonic 0+-p+p √s =200 GeV 0p+p√s=200 GeV ω η ω e+e-p+p √s=200 GeV PHENIX has measurement of ω in p+p,d+Au & Au+Au Measurement of ωe+e- complicated by combinatorial background Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  8. , Ks - meson decay modes p+p d+Au Au+Au  Analysis is not complete Ks p+p √s =200 GeV d+Au√s=200 GeV Au+Au √sNN=200 GeV Ks 00p+p √s=200 GeV PHENIX has measurements of  in p+p,d+Au & Au+Au Measurement of Ks in Au+Au are in progress Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  9.  - meson spectra p+p d+Au Au+Au • PHENIX has a complete set of measurement of K+K- • First results on e+e- suffer from lack of statistics • e+e- analysis in p+p is in progress Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  10. ω - meson spectra ω e+e-Au+Au √sNN=200 GeV PHENIX Preliminary hadronic leptonic 0+- (0)p+p, d+Au, AuAu√sNN =200 GeV PHENIX mapped out high pTω in p+p, d+Au, produced a first result in Au+Au ω,e+e- in p+p are not ready yet, but the signal there is very clean Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  11. Result consistency checks Similar analysis Similar analysis Agree    K Agree Agree K  PRC75 (2007) 024909 nucl-ex/0702046 (QM2006) Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  12.  - meson yield and temperature • -meson temperature ~same @√sNN=62,200 GeV & is constant with Npart • -meson yield grows both with √sNN & centrality • Yield in e+e- channel seems to be higher than that in hadronic channel. More accurate measurements are required to make any conclusions Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  13. η,K / 0ratio  2 K0S 00 PRC75 (2007) 024909 nucl-ex/0702046 (QM2006)  /0 in p+p@√sNN = 200 GeV = 0.48 ± 0.02(stat) ± 0.02(syst)  /0 in d+Au @ √sNN = 200 GeV = 0.47 ± 0.02(stat) ± 0.02(syst)  /0 in Au+Au @ √sNN = 200 GeV = 0.40 ± 0.04(stat) ± 0.02(syst) Ks/0 in p+p @ √sNN = 200 GeV = 0.45 ± 0.01(stat) ± 0.05(syst) Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  14. ()/ 0ratio ω0+-ω0 nucl-ex/0611031 acc. to PRC nucl-ex/0702046 (QM2006) /0 inp+p Run5 @ √s = 200 GeV = 0.81 ± 0.02(stat) ± 0.07(syst) /0 ind+AuRun3 @ √sNN = 200 GeV = 0.94 ± 0.08(stat) ± 0.12(syst) Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  15. Nuclear Modification Factor d+Au Au+Au  ω RAA RdA for all light mesons compatible with one RAA for ω &  at high pT is below one, same as other mesons Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  16. Mass peak shape p+p d+Au Au+Au  PHENIX Preliminary PHENIX Preliminary ω All  measurements at low pT show agreement with PDG ω provides no evidence of change in mass at high pT Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  17. Summary • PHENIX has measured , Ks, ω and - mesons in hadronic and di-electron decay channels • All mesons behave consistently with other mesons in different collision systems and at different energies. • The baseline measurements (p+p √s=200GeV) exist in hadronic channels and are being analyzed in leptonic channel using accumulated data. • Measured particle ratios at high pT are: • /0 inp+p @ √s = 200 GeV = 0.81 ± 0.02(stat) ± 0.07(syst) • /0 ind+Au@ √sNN = 200 GeV = 0.94 ± 0.08(stat) ± 0.12(syst) • /0 in p+p@ √sNN = 200 GeV = 0.48 ± 0.02(stat) ± 0.02(syst) • Ks/0 in p+p@ √sNN = 200 GeV = 0.45 ± 0.01(stat) ± 0.05(syst) • Current di-electron analysis in heavy ion collisions is in progress and needs improvement on the background conditions and more data.Next major step is to take high statistics and high purity di-lepton measurement in (d)A+A Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  18. Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  19. Backups Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  20. PHENIX Experiment e+ ,ω e-   K+K- BR = 49.2  0.7%   e+e- BR = 2.97 0.04 10-4   e+e- BR = 7.18 0.12 10-5  0 BR = 8.90  0.25%   0+- BR = 89.1  0.7% PHENIX acceptance : -0.35 < h < 0.35 2 x 90o for two arms Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

  21. Compare of all ->KK data Run4 Victor Ryabov, PNPI SQM 2007 Levoca Jun.27, 2007

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