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f- Meson Production in d - Au Collisions at √s = 200 GeV

Dipali Pal Vanderbilt University (for the PHENIX Collaboration). f- Meson Production in d - Au Collisions at √s = 200 GeV. Outline. Physics motivation PHENIX experiment Particle identification Data analysis f meson reconstruction Corrections

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f- Meson Production in d - Au Collisions at √s = 200 GeV

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  1. Dipali Pal Vanderbilt University (for the PHENIX Collaboration) f-Meson Production in d - Au Collisions at √s = 200 GeV Hot Quarks 2004, Taos Valley

  2. Outline • Physics motivation • PHENIX experiment • Particle identification • Data analysis • f meson reconstruction • Corrections • Results ( f  K+K- and f e+e-) • Summary and outlook Hot Quarks 2004, Taos Valley

  3. Physics motivation f mesons • Chiral symmetry restoration and medium effects - mass shift, width broadening - branching ratios in K+K- and e+e- decay channel  Simultaneous measurement of f K+K- and f  e+e- • Strangeness production - f meson yield • Particle production mechanism - Rcp, elliptic flow • Au – Au & d – Au collisions • Distinguish between hot and cold partonic matter • Evolution of medium properties with density and temperature • Probing nuclear effects Hot Quarks 2004, Taos Valley

  4. PHENIX Setup Collision vertex and centrality: Beam-beam Counter K- K+K- Tracking : DC – PC1 – PC3 Momentum K+ K- •  K+K- Kaon identification: TOF: |Dh| < 0.35, Df = 45o PbSc (East): |Dh| < 0.35, Df = 45o PbSc (West): |Dh| < 0.35, |Df| = 90o K+ K+K- fK+K- Minimum-bias |zVertex| < 30 cm Nevt = 54 M f e+e- ERT_Electron trigger |zvertex| < 30 cm Nevt (ERT) = 31M  1.9 G Minimum bias f e+e- Electron identification: RICH + EMC |Dh| < 0.35, Df = 90o, both arms Hot Quarks 2004, Taos Valley

  5. Kaon identification PbSc East and West: 0.3 < p(GeV/c) < 1.0 st ~ 450 ps Time of flight (TOF): 0.3 < p (GeV/c) < 2 st = 130 ps Hot Quarks 2004, Taos Valley

  6. Energy / Momentum Electron identification • Electron PID cuts • NRICH PMT  2 • 0.5<E/p<1.5 • E - from EMC • p from tracking Hot Quarks 2004, Taos Valley

  7. Data analysis and corrections • Same event K+K- and e+e- invariant mass distributions (R). • Combinatorial background (CB) Event mixing within same centrality and Zvertex  Normalization to 2√N++N— • Signal = R - CB • Acceptance correction:  PHENIX Single particle Monte-Carlo simulation - Event generation + Detector hit + Detector response + offline analysis • Other experimental quality control correction:  Run (time) dependent corrections Hot Quarks 2004, Taos Valley

  8. Invariant mass distributions fà K+K- @ d – Au, √sNN = 200 GeV K+ and K- are selected from TOF fà e+e- @ d – Au, √s = 200 GeV Mixed Background Counts per 1 MeV/c2 bin Counts per 10 MeV/c2 S ~ 120 S/B = 1/4 G = 4.409 ± 0.711 MeV/c2 e+e- invariant mass (GeV/c2) Hot Quarks 2004, Taos Valley

  9. f meson transverse mass spectra (I) Fitted with exponential function in mT e+e- 1/2mT dN/dmTdy(GeV/c2)-2 PHENIX Preliminary PHENIX Preliminary mT(GeV/c2) PHENIX Preliminary PHENIX Preliminary dN/dy=0.0560.015(stat) 50%(syst) T=326 94(stat)  53%(syst) MeV Hot Quarks 2004, Taos Valley

  10. meson transverse mass spectra (II) SPS result Central Pb-Pb 158 A GeV NA49: f K+K- T = 305 MeV dN/dy ~ 2.35 • NA50: •  m+ m-T = 227 MeV • No specific quote of dN/dy • Integrating the mT spectrum gives • dN/dy ~ 13 D. Rohrich et al, J Phys. G 27 (2001) 355 Hot Quarks 2004, Taos Valley

  11. Minimum-bias mT distribution of f (II) dN/dy f  K+K- T f e+e- K+K- 1/2mT dN/dmTdy(GeV/c2)-2 K+K- e+e- e+e- PHENIX Preliminary PHENIX Preliminary PHENIX Preliminary • f yields in d-Au collisions in K+K- and e+e- channels are consistent with each other MT(GeV/c2) Overall fit dN/dy~ 0.0485 T~408 2/DOF=6.7/7 Hot Quarks 2004, Taos Valley

  12. Comparison between f yields in d-Au and Au-Au collisions(f  K+K- ) (Preliminary) (Preliminary) Inverse slope remains constant in Au-Au and d-Au collisions. • yield increases from d-Au to Au-Au system Hot Quarks 2004, Taos Valley

  13. Invariant mass spectra from TOF and PbSc analysis West arm (PbSc) Full east arm ( TOF + PbSc) Work in progress Work in progress • Factor of ~4 more statistics is now available by including the PbSc detectors in east and west arm. • Scope of centrality dependence studies. Hot Quarks 2004, Taos Valley

  14. Summary • First simultaneous measurement of f  K+K- and f  e+e- in d-Au collisions at RHIC. f  K+K- f  e+e- (PHENIX Preliminary) (PHENIX Preliminary) • dN/dy=0.056.015(stat) 50%(syst) • T=326 94(stat) 53%(syst) MeV  Consistent with each other within errors. • f yield jumps from d-Au minimum-bias to Au-Au peripheral • collisions. Then it increases slowly upto Au-Au mid-central, • finally saturates. Hot Quarks 2004, Taos Valley

  15. Outlook • Extended f  K+K- measurement in d-Au collisions with kaons identified with PbSc modules.  Total yield increases by almost a factor of 4.  Better understanding of the systematics is possible.  Centrality dependence of f yield  Particle ratio  Rcp measurements. Hot Quarks 2004, Taos Valley

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