1、p0 reconstruction,Alberto Merchante Gonzlez1 and Siyi Zhou2,1,2013/07/14,1 University of Oxford 2 University of Science and Technology of China,Introduction,2,2013/07/14,Fragmentation function (FF) : probability that hadron h is found in the debris of a parton carrying a fraction z of partons energy
2、,LO：,Hadron production: parton level FF (factorization) QCD first principle (NOT YET); FF evolution function via DGLAP Fitting: parametrization & experimental data (e+e-, SIDIS, pp and p anti-p) Hadron production: unreliable FF theory prediction,Backgrounds,3,2013/07/14,Gunar Schnell Huangshan 2013,
3、Data points 0.6, 0.9 missing BESIII: 3s for p/K 1.0GeV p0 2g production with EMC e+e- p0 +X BESIII, Beijing,0,J/y h K+ K- 0,p0 J/ exclusive decay Contribution from background Energy-momentum conservation p0 e+e- p0 +X p0 reconstruction,p0 Control Samples,4,2013/07/14,We use the decay J/y p+ p- 0 Amo
4、ngst the e+ e- decays, the p+ p- 0 is the most likely product containing 0 The 0 momentum range is very wide, therefore we require it as a product in our decay, which will be subsequently analyzed.,p0 Generator Level,5,2013/07/14,cos(q) has a flat distribution in the p0 rest frame Small angle btw gs
5、 g energy ratio: asymmetry,p0 energy 0.2E0.6 GeV,6,2013/07/14,p0 energy 0.6E1.0 GeV,7,2013/07/14,p0 energy 1.0E1.6 GeV,8,2013/07/14,p0 Generator Level,9,2013/07/14,Conclusions from the generator level cos(q) are flat and energy-independent in the p0 rest frame The angle between the two emitted photo
6、ns is smaller at higher energies, and the RMS deviation does the same.,0.2E0.6,0.6E1.0,1.0E1.6,MC detector vs. Generator Level,10,2013/07/14,MC Detector vs. Generator Level,11,2013/07/14,Detector Level,Generator Level,p0 selection criteria: |cos(q)| 0.9,p0 selection criteria: c2 20,MC detector vs. G
7、enerator Level,12,2013/07/14,Detector Level,Generator Level,p0 selection criteria: angle btw gs p0 energy 0.2, 0.6GeV: angle 80 degree p0 energy 0.6, 1.0GeV: angle 50 degree p0 energy 1.0, 1.6GeV: angle 40 degree,0.2E0.6,p0 energy 0.2E0.6 GeV,13,2013/07/14,p0 energy 0.6E1.0 GeV,14,2013/07/14,p0 ener
8、gy 1.0E1.6 GeV,15,2013/07/14,Conclusions,16,2013/07/14,We study p0 reconstruction with MC data at generator & detector level, and proposed a p0 selection criteria for inclusive p0 measurement. |cos(q)| 0.9 c2 20 angle btw gs p0 energy 0.2, 0.6GeV: angle 80 degree p0 energy 0.6, 1.0GeV: angle 50 degree p0 energy 1.0, 1.6GeV: angle 40 degree,Acknowledgements,17,2013/07/14,Dr. Wenbiao Yan, USTC, for all his efforts and explanations this week.,
