f meson production in =200 GeV proton+proton collisions at PHENIX

1. f meson productionin =200 GeV proton+proton collisions at PHENIX 槌本 裕二 Yuji Tsuchimoto tsuchimoto@bnl.gov High-energy Hadron Physics group, Department of Physics, Hiroshima University, Japan

2. Why am I interested in f ? • Chiral symmetry • Lagrangean in the Normal QCD Vacuum • Mass breaks chiral symmetry • Where chiral symmetry restored • Immediately after Big Bang • Core of neutron star • Heavy Ion Collision Chiral symmetry phase Heavy Ion Collision space temperature neutron star Hadron phase density

3. f f e+ e- Time expansion _ ss fmeson lifetime~44fm/c Thermal equilibrium ~10fm/c Pre-thermal equilibrium ~1fm/c Au Au p p • Observable • Mass • Lifetime • Yield • Branching ratio K+ f K+ f K- K- In medium e+ e-

4. PHENIX • Central Arms completed in Run 2 • can detect electrons, photons, hadrons • |h| < 0.35 and pT > 0.2 GeV/c • Drift Chamber → track curvature → momentum • EMC & TOF → Time of Flight → mass • EMC : High Acceptance, low resolution • TOF : High resolution, low acceptance

5. Kaon Identification p = ± 5s Mass(EMC)[GeV/c2] K = ±2s • Momentum/charge from track curvature measured by Drift chamber • Kaon < ± 2s & Pion > ± 5s for EMC/ToF • |Z vertex| < 30cm • ( DC Quality 63|31 & EMC/ToF Matching < 2s ) Momentum/charge [GeV/c] Momentum/charge [GeV/c]

6. Kaon Identification (cont.) Mass measured by DC & TOF • Mass measured DC and ToF hit timing and path length • Yellow region = Kaon < ±2s ( p<1 GeV/c) p K p Mass [GeV/c2]

7. Invariant Mass and Background Estimation Background estimation Event mixing of K+ and K- |dZ vertex|<5cm && number of K >= 2 , in the same run Scaled as equal number between 1.1 and 1.2 GeV/c2 Invariant mass [GeV/c2]

8. Invariant Mass After Background Subtraction Invariant mass of K+K- by TOF Mean 1018.8±0.6 MeV/c2 Sigma 2.8±0.4 MeV/c2 Fit function : Gaussian Mean and width error are only fitting error Mean 1017.8±1.3 MeV/c2 Sigma 4.2±1.3 MeV/c2 East EMC Mean 1019.8±1.1 MeV/c2 Sigma 3.4±0.9 MeV/c2 West EMC Invariant mass [GeV/c2]

9. Acceptance Correction • Estimate ratio of measured f to thrown f • Low momentum kaon does not reach to tracking detectors due to small spiral • No detector • PID cut efficiency • High momentum kaon is rejected doe to in 5 sigma of p candidate

10. Conditions of the Simulation • Only single f in each event • |h| < 0.6 (flat) • |Z| < 30cm (flat) • 0 < pT < 10 GeV/c (flat) • All f decay to K+K- only in this simulation • 0<f <2p (flat) • 1.0M events • Binning by transverse mass

11. Weighted by initial pT of f • pT distribution of initial phi which I used was flat distribution. It may cause a few % overestimation of efficiency • I weighted by exponential function of w(mT)~exp(-mT/T) initial mT when I fill the histogram. This slope is as same as the slope of results ( iterative ) Weighted Thrown f Weighted detected f

12. f Yield (EMC vs TOF) ToF EMC-W Arbitrary Unit EMC-E • Minimum bias triggered • |z|<30cm • Detector dead-map is not applied completely yet

13. Summary • Consistent mass and width within 1s • Consistent slopes of mT distribution were obtained by DC, ToF and EMC hit Next step • Apply detector dead-map • Calculate cross section of pp→f+X • I’m interested in Run3 f → KK and ee