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Inclusive Photons-Charged Hadrons Azimuthal Correlation. Texas A&M Group Table of Contents: Data set. Photon Identification. Results Summary Ahmed Hamed BNL 03-20-2007 Physics with STAR BEMC: Direct real photons Non-Thermal photons: Thermal photons: 1. Prompt photons. 1. QGP photons. 2. Pre-equilibrium photons. 2. Hadron gas photons. Background Photons:Decayed photons. Schematic Photon Spectrum Bremsstrahlung n Low Pt: A+A collisions: Photons don’t strongly interact with fireball. High pT Allow test of binary scaling for hard processes. Important for interpretation of high-pT hadron suppression at RHIC. Hard: 1/PT Thermal: e-E /T oMotivation: Physics at Mid-Rapidity (sQGP) –High pt suppression The invariant cross section for 0 production in pp collisions at s=200GeV agrees with NLO PQCD predictions over the range 2.0 Pt 15GeV/C. The suppression of 0,s and ,s is very similar which supports the conclusion that the suppression occurs at the parton level. The binary scaling of direct photons is strong evidence that the suppression is not an initial state effect. oRelevant physics: Mid-rapidity and Forward rapidity Collinear assumption Mid-rapidity: Forward rapidity: oForward detection of final state products emphasizes collisions where a large x parton, traveling in the direction of the detected forward particle, collide with a small x parton from the other nucleon. oLarge x partons are most probably valance quarks, and small x partons are most probably gluons. oMotivation: Physics at Mid-Rapidity (sQGP) –Azimuthal distribution Au+Au peripheral Au+Au central flow subtracted Phys Rev Lett 90, 082302 Near-side: peripheral and central Au+Au similar to p+p Strong suppression of back-to-back correlations in central Au+Au ? oMotivation: Physics at Mid-Rapidity (sQGP) –Final state effect • d+Au : enhancement •Au+Au: strong suppression •Suppression of the inclusive yield in central Au+Au is a final-state effect •Near-side: p+p, d+Au, Au+Au similar •Back-to-back: Au+Au strongly suppressed relative to p+p and d+Au •Suppression of the back-to-back correlation in central Au+Au is a final-state effect Analysis: Data Description: <input URL="catalog:star.bnl.gov?production=P06ib,collision=cucu200,trgsetupname =cuProductionHighTower,filename~st_physics,filetype=daq_reco_MuDst,tpc=1,emc=1,sanity= 1,storage!=HPSS" nFiles="all"/> Trigger Id: 66007, 66201, 66203 Total number of event= 13.4M events, High tower data set=2.7M events. 1. Charged particles Isolation cut: oAll the global track “without filtering” is extrapolated to the BEMC towers and BSMD “Eta/Phi” strips. oThe target tower is marked as charged tower oAll of towers in the oThe target strip in addition to its two 3x3 patch neighbors “left/right” around the target tower is marked are marked as charged towers. as charged strip. Analysis: 2. Photon candidate selection: oCluster size: 2 or 1 tower on BEMC “Cluster , 7 Strips in SMD “Eta/Phi” oEnergy seed: 3GeV on towers and 0.01GeV on SMD “eta/phi” oThe photon candidate positioned at distance less than 0.03 -eta and phi units- from the center of the tower and at distance greater than 0.0035 away from the tower edge in eta and 0.0035 in phi. Tracks selection: The associated particles -Primary tracks- are chosen according to the following criteria: The track flag is good. •The number of fit points is greater than 20. •The transverse momentum is greater than 2GeV/c. •The distance to the closet approach is less than 3cm. Azimuthal Correlation: =atan2(sin(_track-_tower),cos(_track-_tower)) Et_trg>4GeV 2GeV/c<Pt<4GeV/c Et_trg>6GeV 4GeV/c<Pt<6GeV/c Et_trg>8GeV 4GeV/c<Pt<8GeV/c Et_trg>10GeV 4GeV/c<Pt<10GeV/c Et_trg>12GeV 4GeV/c<Pt<12GeV/c Et_trg>14GeV 4GeV/c<Pt<14GeV/c Et_trg>16GeV 4GeV/c<Pt<16GeV/c Et_trg>18GeV 4GeV/c<Pt<18GeV/c Et_trg>4GeV 2GeV/c<Pt<4GeV/c Et_trg>6GeV 4GeV/c<Pt<6GeV/c Et_trg>8GeV 4GeV/c<Pt<8GeV/c Et_trg>10GeV 4GeV/c<Pt<10GeV/c Et_trg>12GeV 4GeV/c<Pt<12GeV/c Et_trg>14GeV 4GeV/c<Pt<14GeV/c Et_trg>16GeV 4GeV/c<Pt<16GeV/c Et_trg>18GeV 4GeV/c<Pt<18GeV/c Et_trg>4GeV 2GeV/c<Pt<4GeV/c Et_trg>6GeV 4GeV/c<Pt<6GeV/c Et_trg>8GeV 4GeV/c<Pt<8GeV/c Et_trg>10GeV 4GeV/c<Pt<10GeV/c Et_trg>12GeV 4GeV/c<Pt<12GeV/c Et_trg>14GeV 4GeV/c<Pt<14GeV/c Et_trg>16GeV 4GeV/c<Pt<16GeV/c Et_trg>18GeV 4GeV/c<Pt<18GeV/c Thank you all