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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 1 First measurement of the - meson production with PHENIX experiment at RHIC Victor Ryabov for the PHENIX Collaboration
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 2 Measurement of ω-meson production in different decay channels ( ω π 0 π + π -, π 0 , 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 p T tells us about the production of q-qbar bound states. High p T results on ω and K 0 S add to the picture of the meson R dA in d+Au interactions measured at RHIC
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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 R dA ω/ π 0 ratio Measurement of the mass peak Summary and Outlook
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 4 Charge particles DC-PC1 Momentum resolution: No pID for π + π - Neutrals particles EMC Energy and space resolution: PHENIX acceptance : -0.35 < < 0.35 2 x 90 o for two arms π-π- π 0 π+π+ (see poster 203 in sec.6) Run 3
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 5 + - 0 decay channel: - meson: m = 548 MeV, BR = 23.1 % - meson: m = 783 MeV, BR = 88.8 % 0 decay channel: - meson: m = 783 MeV, BR = 8.5 % 0 0 decay channel: K 0 S - meson: m = 498 MeV, BR = 31.1 % M inv, GeV Run 3 data
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 6 K 0 S π 0 π 0 ω π 0 π + π - π + π - ω π 0 Geometrical acceptance Trigger efficiency Combined PHENIX has different acceptance and trigger efficiencies for the decays under study Consistency of the results is a powerful cross check
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 7 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 p T Correction applies to ω π 0 π + π - while ω π 0 is unaffected and remains a cross check. π - E kin π + E kin π 0 E kin 1.0 0.5 3.0 5.0 7.0 9.0 p T [GeV/c]
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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 %
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 9 First result on the ω-meson production at RHIC energy. Broad p T coverage from 2.5-9.5GeV/c Good agreement between two independent decay modes
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 10 First result on the ω-meson production in d+Au. Broad p T coverage from 3 GeV/c to 9 GeV/c Good agreement between to independent decay modes
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 11 K 0 S spectra up to p T of 6.5 GeV/c in p+p and 8.5GeV/c in d+Au Gap between K 0 S 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 p T. Provides a good cross check for analysis approach hep-ex/0501059
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 12 CERES-TAPS measured ω-meson production in hadronic collisions at lower p T At √31 GeV (π+Be E706) spectrum have steeper slope Instead of comparing spectra we can compare ω/π 0 ratio
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 13 p+p d+Au First result on the Vector/Pseudo- scalar meson ratio at RHIC at high p T Ratios are similar in p+p and d+Au and close to 1 Ratios do not change in a range of p T from 2 GeV/c to 9 GeV/c within systematic errors PYTHIA (default) tuned to LEP data at lower √s suggests slightly higher ratio
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 14 π0π0 ηK0SK0S φ R dA measured for - mesons is consistent with 1 within the systematic errors Heavier mesons tend to show higher value of R dA
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 15 PHENIX can measure position of the centers of ω-meson mass peaks at different p T. 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 M inv, GeV 0+-0+-
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 16 Au+Au miss-ID combinatorics clear peak PHENIX can measure - mesons in AuAu at √s NN = 200 GeV See clear signal in 0 channel at p T > 7 GeV/c Statistics of Run4 let to measure centrality dependence at high p T (poster 193, session 6) 0 Counts Half of Run4 statistics, loose cuts
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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 p T range from 2.5 to 9.5 GeV/c, Two decay modes for ω-meson give consistent results, R dA = 1.3 ± 0.2 in the range of measurement, ω/ π 0 (inclusive) = 0.9 ± 0.1 in p+p, Ratio is independent of p T within systematic errors, ω-meson mass is consistent with the PDG value, Clear peaks are seen in Au+Au data at high p T K-meson measurement is consistent with existing results and extended to substantially higher p T. 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.
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 18
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 19
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Victor Ryabov (PNPI) for the PHENIX Collaboration QM2005 Budapest Aug,06,2005 20 d+Au 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)
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