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Low mass vector meson measurements at RHIC Systematic Measurement of omega mesons in PHENIX

e ＋. ω. e ー. ω. ω. Low mass vector meson measurements at RHIC Systematic Measurement of omega mesons in PHENIX. π +. π 0. π 0. ー　　　　　　　　　　　　　　　　　　　　　ー. γ. Misaki Ouchida Hiroshima University For the PHENIX Collaboration. π ー. γ. γ. γ. γ. OUTLINE. Introduction

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Low mass vector meson measurements at RHIC Systematic Measurement of omega mesons in PHENIX

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  1. e＋ ω eー ω ω Low mass vector meson measurements at RHICSystematic Measurement ofomega mesons in PHENIX π+ π0 π0 ー　　　　　　　　　　　　　　　　　　　　　ー γ Misaki Ouchida Hiroshima University For the PHENIX Collaboration πー γ γ γ γ

  2. OUTLINE • Introduction Why Low Mass Vector mesons ? • Experiment Which decay mode do we measure in PHENIX? • Analysis Highlight How do we approach? • Results & Discussion What do we see? • Summary

  3. Introduction WhyLow Mass Vector mesons? •  e+e- (BR:7x10-3%) w p0g (BR:9%) Reconstructed Efficiency ωpT p+p • Systematic Study of • Low Mass Vector Mesons • different decay mode • (lepton, hadron) • different collision mode • (p+p, d+Au, A+A) Promising probe to study the properties of the deconfined state d+Au Matter ( life time~10fm/c ) omega meson ( life time 23fm/c ) A+A phi meson ( life time 46fm/c ) Physics… Signal for Chiral Symmtery Restoration Signal for Jet Quenching Low pT High pT

  4. Suppression as a Probe of QGP Introduction WhyLow Mass Vector mesons? Hadron Production will be suppressed due to the jet quenching occurred in the heavy-ion collisions as an effect of the matter The inclusive pi0 production in Au+Au QGP Nuclear Modification Function In the absence of nuclear effects: RAA=1 PRL 91. 072301 (2003)

  5. Experiment Which decay mode do we measure ? γ γ π0 π0 γ γ e+ π+ e- ω ω→π0π+π- ω→π0γ γ γ φ→e+e- ω→e+e- Hadron ID Energy Momentum π- Momentum Electron ID PHENIX spectrometer <Global detector> • BBC & ZDC : Event trigger, Collision vertex, Centrality <Central arm> • Acceptance ⇒ pseud-rapidity range : |η| < 0.35 azimuthal angle : 2x90 degree • DC & PC : tracking, momentum • RICH & EMC : electron ID • TOF, EMC : hadron ID <Muon arm> • MuID : muon ID ⇒PHENIX consists of multi-purpose detector to measure rare probe from collisons.

  6. Analysis HighlightHowdo we approach? d+Au d+Au w p0g p+p p+p, d+Au collisions wφ e+e- wφ e+e- p+p w p+p-p0 Both leptonic and hadronic decay channel are measured

  7. Analysis HighlightHowdo we approach? Challenge to A+A Collisions Quest for Low Mass Vector Mesons in huge huge Background

  8. Analysis HighlightHowdo we approach? Best Cuts S/√B (significance) No Cuts pT(ω) [GeV/c] Improving S/N • Further Cut Optimization e.g.w p0g @ Au+Au Kinematical Cuts for Reconstruction ･Transverse Momentum of ･Photon Energy ･Width of Invariant Mass Rising Minimum Cuts Use Best Cuts that improve S/√B (significance) the most

  9. Analysis HighlightHowdo we approach? BG BG Signal BG wφ Subtracting Backgrounds ( 2 body:wφ e+e- , φ K+K-) conbinatorial backgrounds w,f→ee Extract by Event Mixing AN 612

  10. Analysis HighlightHowdo we approach? Subtracting Backgrounds ( 3 body:w p0g(p02g)) Mixed event w Reconstructed invariant mass Peripheral (cent 60~92 %) 3.5<pT<4.5[GeV/c] BG2 Black: FG count BG3 BG1 Magenta:BG1+BG2+BG3 after subtraction of BG1+BG2+BG3 [GeV/c^2] Gaussian (Mean and With are Fixed by Embedding simulation)

  11. Results & Discussion Whatdo we see? • Spectra (p+p & d+Au)

  12. Results & Discussion Whatdo we see? Getting down in higher centrality • Spectra (Au+Au) w p0g , w e+e-@ Au+Au Suggesting Hadron suppression

  13. Results & Discussion Whatdo we see? Interesting systematic measurement of hadron suppression

  14. Results & Discussion Whatdo we see? Interesting systematic measurement of hadron suppression

  15. Summary Physics… yet to be discussed… provide intriguing result Signal for Chiral Symmtery Restoration Signal for Hadron Suppression • PHENIX measured Low Mass Vector Meson, φandω production in both leptonic and hadronic channels in different collision system. • Spectra show good agreement among several decay channels in p+p and d+Au • A+A results have an ability to discuss hadron suppression providing intriguing systematic results. Low pT High pT Systematic measurement of omega in PHENIX will be published in near furture

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  17. Results & Discussion Whatdo we see? w p0g@ Au+Au • Nuclear Modification Function: RAA φ K+K-@ Au+Au Suggesting Hadron suppression same as other mesons Suggesting Hadron suppression same as other mesons

  18. Results & Discussion Whatdo we see? • Spectra (A+A) w p0g , w e+e-@ Au+Au PHENIX Preliminary & Work In Progress wφ e+e- , φ K+K- @ Au+Au PHENIX Preliminary Suggesting Hadron suppression same as other mesons

  19. Analysis HighlightHowdo we approach? Cu+Cu w p0g Using detector thresholds RHIC EMCal Chose the data set that only take high pT  High statistic

  20. Omega Spectra (together) 0-20% M.B. 20-60% 60-92%

  21. PHENIX

  22. Another Energy Correction Correct Measured Energy Value to True Energy Value (Assumed as E1E2 has a true value) If energy is measured within the energy resolution band (yellow and red band), shrink it to E1E2 curve. Minimize Χ2 value= ((E1-E1(measured))/σE1)2 + ((E2-E2(measured))/σE2)2 where E1*E2 = m(pi0PDG)/2(1-cos) Energy reso. corrected uncorrected Can correct also pT!

  23. d+Au results

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