Di-hadronazimuthalcorrelationsinhead-oncollisionsofAu.pptVIP

Di-hadron azimuthal correlations in head-on collisions of Au + Au at in AMPT Liu, Qingjun Beijing Institute of Petro-chemical Technology Weihai, Shandong University, Aug. 9-14, 2009; 1. Why di-hadron azimuthal correlations 2. Why the correlations in head-on collisions 3. What the results look like ; 1. Why di-hadron azimuthal correlations It is per-trigger azimuthal distribution of the associate particles with respect to the trigger. A: trigger particle, from high pT parton fragmentation B: associated particles, other than the trigger Subtraction of background must be done.;1. Why di-hadron azimuthal correlations;Slide from G.L. Ma of SINAP, CAS.;AMPT results: slide from Zhang Song of SINAP, Shanghai.; 2. Why study the correlations in head-on collisions It is argued that the double peaked structure may be out of improper subtraction of background due to elliptic flow. Then if subtraction of that part of background is not necessary, can we still see that away-side structure? When is the subtraction not necessary? The answer is when impact parameter b = 0 fm. How to get events with b = 0 fm? Using AMPT model. ;AMPT, by Dr. Ko Che-Ming, Dr. Zhang Bin, Dr. Li Bao-An etc.; 3. What the results look like ;CONCLUSION: If the away-side double peak structure come solely from improper background subtraction in mid-central and top 5% central collisions, then one may not expect to see the structure in head-on collisions where elliptic flow does not exist. However the structure as we saw does exist in head-on collisions in AMPT model. Therefore, the structure does have dynamical origins in mid-central through top 5% central collisions.