M. Muniruzzaman University of California Riverside For PHENIX Collaboration

1. Reconstruction of f Mesons in K+K- Channel for Au-Au Collisions at sNN=200 GeV by the PHENIX Experiment at RHIC M. Muniruzzaman University of California Riverside For PHENIX Collaboration

2. Outline • Motivation • Detector Setup • Particle Identification • Data Sample Selection • f Invariant Mass Reconstruction • Transverse Mass Spectra of f • f Yield and Slope Parameter

3. An enhanced f-meson production has been suggested as a signature for the formation of a deconfined phase. Motivation • Chiral symmetry restoration expected in heavy ion collisions may lead to medium modifications of f-meson properties. R. Rapp nucl-th/0204003 • The change in the branching ratio in leptonic and hadronic channels may point to the chiral symmetry restoration. • The measurement of f in K+K- channel combined with the measurement in the e+e- channel may be a good diagnostic tool of the new phase created in the heavy ion collisions.

4. PHENIX Central Arm Capable of Measuring hadrons, electrons and photons PHENIX in Run-II Tracking: Drift Chamber Pad Chamber1 Pad Chamber3 Kaon Identification ElectromagneticCalorimeter Time-of-Flight Detector Excellent Particle Identification Capability TOF

5. Particle Identification Particle Identified through High Resolution Time-of-Flight Detector Particle Identified through Electromagnetic Calorimeter Timing resolution ~ 480ps Timing resolution ~ 120ps

6. Data Sample Particles identified in TOF are used for this analysis • 27.94 Million Minimum Bias Au+Au events. • Track Selection • 3s track projection matching. • Momentum between 300MeV/c and 2.0 GeV/c. • 2s cut on the calibrated mass2 of kaon at TOF. Mass squared of Particles are Calculated. Sample is selected on its mass2 Distribution 2s around the peak of mass2

7. f K+K- Signal in the TOF • K+ and K- from same event are paired together to give Actual N+- • K+ and K- from different events, but from same centrality and vertex class, are paired together to give Mixed N+- • Mixed N+- Normalized by Actual Pair N++ and N--as CB=2(N++.N--),where CB stands for the combinatorial background • Signal = Actual N+- - CB Background Actual Pairs BW convoluted with Gaussian f signal : 2128179 S/B = 1/10.1 Mass peak position and width are consistent with the PDB value

8. mt Distribution : Analysis Procedure 3 Centrality Classes : 0%-10%, 10%-40%, 40%-92% 9 mt bins : 1.2-1.6, 1.6-1.8, 1.8-2.0, 2.0-2.2, 2.2-2.4, 2.4-2.6, 2.6-2.8, 2.8-3.0, 3.0-4.0 GeV where Nf = f signal, the number of counts in 2G window in the invariant mass plot MC = Monte-Carlo f eembed = 1 - efficiency loss due to high occupancy cf = Centrality fraction of the cross-section BR = Branching Ratio (0.49 for f decaying into K+K-) Dmt = width of the mt bin Fitting Function:

9. f mtDistribution PHENIX Preliminary PHENIX Preliminary Central (0-10%) T = 367 49 MeV Peripheral (40-90%) T = 35234 MeV 1/2pmt d2N/dydmt 1/2pmt d2N/dydmt mt (GeV) mt (GeV) PHENIX Preliminary PHENIX Preliminary Mid Central (10-40%) T = 36426 MeV Min-bias T = 37120 MeV 1/2pmt d2N/dydmt 1/2pmt d2N/dydmt mt (GeV) mt (GeV)

10. Summary on dN/dy and Inverse Slope Parameter dN/dy 1/Np dN/dy Shifted left for better viewing Shifted left for better viewing Np Np PHENIX Preliminary T (MeV) Np

11. Summary • f mesons are reconstructed via K+K- channel for the Au-Au Collisions at SNN=200GeV. • mt spectra of f are studied for three centralities. • The spectra were fitted with an exponential and the f yield and inverse slope parameters were extracted from the fit. • Centrality dependence of yield is studied. • The inverse slope parameters appear to be unaffected with the centrality. • The systematic error on the slope parameters are still under investigation. • Inclusion of the higher statistics Electromagnetic Calorimeter is underway.