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Reconstruction of f Mesons in K + K - Channel at s=200 GeV by the PHENIX Experiment at RHIC

Reconstruction of f Mesons in K + K - Channel at s=200 GeV by the PHENIX Experiment at RHIC. Mohammed Muniruzzaman University of California Riverside. An enhanced f -meson production has been suggested as a signature for the formation of a deconfined phase

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Reconstruction of f Mesons in K + K - Channel at s=200 GeV by the PHENIX Experiment at RHIC

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  1. Reconstruction of f Mesons in K+K- Channel at s=200 GeV by the PHENIX Experiment at RHIC Mohammed Muniruzzaman University of California Riverside

  2. An enhanced f-meson production has been suggested as a signature for the formation of a deconfined phase Medium modifications of f-meson properties might be related to the expected chiral phase transition The change in the branching ratio in leptonic and hadronic channels may point to the chiral symmetry restoration. Sensitive to strangeness enhancement Lifetime of f (tf ~44fm/c) makes it a wonderful probe of the deconfined phase Motivation R. Rapp nucl-th/0204003

  3. 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

  4. PHENIX during last 10 days FY2001 – 02 Ecm=200 GeV FY2000 Ecm=130 GeV Run Condition • RHIC Beam Delivered at PHENIX • Au-Au at Ecm=200 GeV • At 42 mb-1 • Vertex between 45 cm • Over 50% of Data accumulated in the last two weeks of Au-Au Run • p-p at Ecm=200GeV at 700 nb-1 After Imposing Strict Data Quality Control, 27 Million min-bias data were selected for analysis 92 million min-bias data recorded for Au-Au Run

  5. PHENIX Event Display So many Tracks !! Need good Particle ID f K+K- analysis is possible if we can point out which tracks are kaons

  6. Particle Identification Particle Identified through High Resolution Time-of-Flight Detector Particle Identified through Electromagnetic Calorimeter

  7. Data Sample Selection Mass squared of Particles are Calculated. Sample is selected on its mass2 Distribution • 27 Million Minimum Bias Au+Au events • Track Selection • 3 s track projection matching at PC3 • 3 s matching on PC3 • Best quality DC tracks • Energy Loss in TOF > 2 MeV • Momentum between 200MeV/c and 1.2 GeV/c in Time of Flight • Momentum upto 900 MeV/c in EMCal • 3s cut on the calibrated mass2 of kaon • 5s above the Pion mass2 band 3s around the peak of mass2

  8. f Invariant Mass Fit with a Breit-Wigner Convoluted with a Gaussian Actual pairs Mixed background fSignal : 1141±87.4 Mixed N+- Normalized by Actual Pair N++ and N--as 2(N++.N--)

  9. f Invariant 2k Another approach to extract f signal by looking at the difference of 4-momenta of kaons: k = (p1m-p2m)2 • Advantages: • Pushes the f peak away from the kinematic edge • Puts any correlated pairs into a different region of phase space Actual pairs Mixed background fSignal : 1135±116.86 Mixed N+- Normalized by Actual Pair N++ and N--as 2(N++.N--)

  10. f 4s PID Cut Background above f “Ks?” • Investigate background above f, m~1.07 GeV • Make looser PID cut (4s) • Subtraction done by normalizing to region above peak • Larger contamination from secondary peak • Ks from misidentified momentum in the TOF array? • Reconstruct mass assuming particles are pions • Peak shows up at ~494 MeV ~MK • Make a tighter PID cut 1s • Extra mass peak largely disappears mkk Ks “f” mpp f 1s PID Cut

  11. S= 145 S/B=1/12.14 Acceptance vs mt • 3 Centrality Classes • 0%-10%, 10%-40%, 40%-92% • 8 Mt Bins 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 • Fitting for each centrality and Mt bins are done by fixing the values of mass and G from the fit of min bias, and letting the constant free. Central low pt 0%-10% centrality, 1.8<mt<2.2 S= 35 S/B=1/3.1 mid-central high pt 10%-40% centrality, 3.0<mt<4.0 S= 38 S/B=1/1.45 Work in progress toward mt distribution Peripheral 40%-92% centrality, 2.0<mt<2.2

  12. f Invariant Mass in EMCal • Advantages: • Large Acceptance • Kaons accepted upto p<900 Mev • Complements the TOF measurements in the low mt region Actual pairs Mixed background

  13. Summary • Using the excellent PID capability of PHENIX Time of Flight Detector f is reconstructed via K+K- channel for the Au-Au Collisions at SNN=200GeV. • The mass is fitted with a Breit-Wigner Convoluted with a Gaussian with a resolution of 1.2 MeV determined from simulation. The preliminary fit values for the mass and G agrees well the PDB values. The systematic errors on these numbers are still under investigation. • With the available statistics 3 bins of centrality and 8 bins in mt could be made which enabled us to study the yield of f. This analysis is still in progress. • It has been demonstrated that f can be reconstructed through Electromagnetic Calorimeter. This will enable us to accumulate more statistics and probe into the low mt region.

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