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First measurement of the  - meson production with PHENIX experiment at RHIC

First measurement of the  - meson production with PHENIX experiment at RHIC. Victor Ryabov for the PHENIX Collaboration.

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First measurement of the  - meson production with PHENIX experiment at RHIC

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  1. First measurement of the  - meson production with PHENIX experiment at RHIC Victor Ryabov for the PHENIX Collaboration Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  2. Measurement of ω-meson production in different decay channels (ωπ0π+π-, π0, e+e-)carries information about possible modification of the media produced in HI collisions. • Measurement of hadronic decays of the ω-mesons in p+p collisions creates a baseline for the comparison to other decay modes and collision systems: • Comparison ωhadrons vs. ωdi-electrons in p+p • Comparison of the same ratio in A+A • ω is an important ingredient for calculation of electron cocktails used in various PHENIX analyses. • Vector-to-Pseudoscalar meson ratio (/0) at high pT tells us about the production of q-qbar bound states. • High pT results on ω and K0S add to the picture of the meson RdA in d+Au interactions measured at RHIC Motivation Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  3. Decays under study • Experimental setup • Analysis details: • Acceptances • Phase space • Systematic errors • Results: • Spectra, cross-checks and comparisons • RdA • ω/π0 ratio • Measurement of the mass peak • Summary and Outlook Outline Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  4. Run 3 Charge particles (p+ p-) : DC-PC1 Momentum resolution: No pID for π+π- Neutrals particles (po g) : EMC Energy and space resolution: π+ π0 π- Experimental Setup PHENIX acceptance : -0.35 < h < 0.35 2 x 90o for two arms (see poster 203 in sec.6) Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  5. 0decay channel:  - meson: m = 783 MeV, BR = 8.5 % Run 3 data + - 0 decay channel:  - meson: m = 548 MeV, BR = 23.1 %  - meson: m = 783 MeV, BR = 88.8 % Minv, GeV Decays under study Minv, GeV 0 0 decay channel: K0S - meson: m = 498 MeV, BR = 31.1 % Minv, GeV Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  6. PHENIX has different acceptance and trigger efficiencies for the decays under study Consistency of the results is a powerful cross check K0Sπ0π0 ωπ0 ωπ0π+π-π+π- Geometrical acceptance Acceptance Trigger efficiency Combined Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  7. π0 Ekin GEANT assumes uniform density of the phase-space We used measured (e.g.:PRL(1962) 325) density distribution profile resulting in 5%-15% correction depending on pT Correction applies to ωπ0π+π- while ωπ0 is unaffected and remains a cross check. π- Ekin π+ Ekin Phase space density 1.0 0.5 3.0 5.0 7.0 9.0 pT [GeV/c] Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  8. Calorimeter related errors: • Geometrical acceptance 4-8 % • Energy resolution 1-5 % • Energy scale 3-23 % • Tracking related errors: • DC-PC1 tracking efficiency negligible • Matching cuts 2 % • Momentum cuts for charged tracks negligible • Run by run variation 2-3 % • Trigger related errors: • ERT trigger efficiency 3-7 % • Trigger efficiency and correction 10 % • Analysis uncertainties: • 0 selection cuts 3-10 % • Conversion correction uncertainty 3-6 % • Peak extraction uncertainty 9-13 % • Branching ratio uncertainties 0.8-5 % • Phase space correction 2-8 % Systematic errors Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  9. spectra in p+p First result on the ω-meson production at RHIC energy. Broad pT coverage from 2.5-9.5GeV/c Good agreement between two independent decay modes w Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  10. spectra in d+Au First result on the ω-meson production in d+Au. Broad pT coverage from 3 GeV/c to 9 GeV/c Good agreement between to independent decay modes w Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  11. hep-ex/0501059 spectra K0S spectra up to pT of 6.5 GeV/c in p+p and 8.5GeV/c in d+Au Gap between K0S and K+ K- measurement prevents direct comparison to Time-of-Flight measurements (talk by Maya Shimomura). PHENIX results are consistent with measurements of STAR in the region of overlap and go to higher pT. Provides a good cross check for analysis approach S 0 K Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  12. CERES-TAPS measured ω-meson production in hadronic collisions at lower pT At √31 GeV (π+Be E706) spectrum have steeper slope Comparison to existing data Instead of comparing spectra we can compare ω/π0 ratio Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  13. d+Au First result on the Vector/Pseudo-scalar meson ratio at RHIC at high pT Ratios are similar in p+p and d+Au and close to 1 Ratios do not change in a range of pT from 2 GeV/c to 9 GeV/cwithin systematic errors PYTHIA (default) tuned to LEP data at lower √s suggests slightly higher ratio ratio p+p w/p Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  14. π0 η K0S φ RdA measured for  - mesons is consistent with 1 within the systematic errors Heavier mesons tend to show higher value of RdA dA w R Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  15. 0+- PHENIX can measure position of the centers of ω-meson mass peaks at different pT. Current (run3) measurements are limited by statistics. Possibility to measure the width of ω is under investigation In run3 the widths of the peaks is about 22 MeV at natural width of 8.5 MeV Minv, GeV mass w Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  16. Counts PHENIX can measure  - mesons in AuAu at √sNN= 200 GeV See clear signal in 0 channel at pT > 7 GeV/c Statistics of Run4 let to measure centrality dependence at high pT (poster 193, session 6) Au+Au 0 clear  peak miss-ID  combinatorics First look at Au+Au data Half of Run4 statistics, loose cuts Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  17. The first measurement of the ω-meson production at RHIC in p+p and d+Au systems is shown: • The spectra are measured in pT range from 2.5 to 9.5 GeV/c, • Two decay modes for ω-meson give consistent results, • RdA = 1.3 ± 0.2 in the range of measurement, • ω/π0 (inclusive) = 0.9 ± 0.1 in p+p, • Ratio is independent of pT within systematic errors, • ω-meson mass is consistent with the PDG value, • Clear peaks are seen in Au+Au data at high pT • K-meson measurement is consistent with existing results and extended to substantially higher pT. • Future plans: • Run5 p+p with x15 more statistics, • Run4 Au+Au with 1.5B events on tape, • Run5 Cu+Cu with statistics comparable to Au+Au, • Other decay modes. Summary and Outlook Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  18. Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  19. Backups Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

  20. counts Statistics of Run3 d+Au is sufficient only to see the indication of -meson in e+e- channel. No comparison can be done with hadronic channel Statistics of Run4 Au+Au allows to produce estimation of the dN/dy (poster 195, session 6) Comparison to dielectron channel counts d+Au Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005

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