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Dai-Mei Zho u

(IOPP/CCNU). Dai-Mei Zho u. Collaboration with:. Yun Cheng (CCNU) Xu Cai (CCNU) Yu-Liang Yan (CIAE) Bao-Guo Dong (CIAE) Ben-Hao Sa (CIAE). 3. 2. 5. 1. Motivation. Physical ingredients in PACIAE. Roughly fitting model parameters to dNch/dy. 4. Results of &.

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Dai-Mei Zho u

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  1. (IOPP/CCNU) Dai-Mei Zhou Collaboration with: Yun Cheng (CCNU) Xu Cai (CCNU) Yu-Liang Yan (CIAE) Bao-Guo Dong (CIAE) Ben-Hao Sa (CIAE)

  2. 3 2 5 1 Motivation Physical ingredients in PACIAE Roughly fitting model parameters to dNch/dy 4 Results of & Au+Au @ 0.2 TeV Pb+Pb @ 2.76 TeV p+Au @ 0.2 TeV and p+Pb @ 5.02 TeV p+p @ 7 TeV Conclusions 5

  3. is important observable relevant to the exploring of sQGP measurement is such hard that (10-100)% discrepancy may exist among methods Event plane method Lee-Yang zero point method Two-particle cumulant Cumulant method Four-particle cumulant Six-particle cumulant 1 Motivation

  4. conventional hadronic transport (cascade) models underestimated experimental data: UrQMD, AMPT(def) , & PACIAE 2.0 etc., In order to meet with data, they have to update AMPT_def to AMPT_sm, for instance, by (a lack of pressure in the model may be the reason and that the partonic interactions have to be taken into account ) • Melting hadrons (strings) from HIJING to partons • to amplify parton rescattering • (generates the large enough pressure) (B) enlarge parton cross section from 3 mb to 10 mb (C) parton hadronized with coalescence rather than string fragmentation

  5. t Half minor axis of the ellipse Half major axis of the ellipse Almond-like Dynamical evolution of asymmetry Initial spatial space asymmetry: (ellipse) the radius of nucleus final momentum space asymmetry:

  6. However, in PYTHIA (PACIAE2.0) particle momentum from SF (string fragmentation) azimuthal angle of particle transverse momentum sampled according to exponential/Gaussian distribution arranged on the circle with radius of This symmetry arrange strongly cancels the final hadronic state transverse momentum asymmetry

  7. We modify it by half major axis half minor axis On the circumference of an ellipse With extra deformation parameter , experimental data are then able to be better described. Comput. Phys. Commun., 184(2013)1476.

  8. Parameter of can be related to the deformation parameter of in the initial spatial phase space as an extra model parameter instead of Spatial reaction plane eccentricity: the average over the nucleon spatial distribution

  9. geometrical eccentricity of the initial spatial overlap zone

  10. The participant eccentricity for the p+p and p+A collisions one can only regard itself as an extra model parameter

  11. The Fourier expansion of particle transverse momentum azimuthal distribution reads the azimuthal angle of particle transverse momentum azimuthal angle of reaction plane

  12. In the theoretical study, the beam direction impact parameter vector the reaction plane is the plane reaction plane angle between the reaction plane and the axis.

  13. Denotes the particle-wise average, i.e. the average over all particles in all events

  14. 2 Physical ingredients in PACIAE PACIAE is based on PYTHIA (A) Initiation (i) Distributing nucleons according to Woods Saxon, (ii) participant nucleons inside OLZ • spectator nucleons outside OLZ but inside nucleus- nucleus collision system y OLZ p T b z x

  15. (iv) Construct nucleon collision time list with NN total cross section & straight trajectory (v) Each NN collision performed by PYTHIA with switching-off SF & breaking diquark . (vi) Resulted initial state ,consist of partons after all of the NN collision pairs are exhausted

  16. (B) Parton re-scattering (parton evolution) (i) Construct parton collision time list with parton-parton total cross section (ii) Perform each parton-parton collision by 22 pQCD differential cross section (C) Parton hadronization with SF or CM coalescence model (D) Hadron re-scattering (i) Construct hadron collision time list with hh total cross section (ii) Perform each hh collision by differential hh cross section Ben-Hao Sa, Dai-Mei Zhou, et.al., Comput. Phys. Commun. 183(2012)333, 184(2013) 1476

  17. 3 Roughly fitting model parameters to dNch/dy The model parameters are all fixed as the same as default Values given in PYTHIA, except the K factor,

  18. 4 Results of & event-plane PHENIX, PRC80 (2003) 024909 As for the best model parameter C~2 in the left panal but 1 in the right panel, which should be attributed to the particle transverse asymmetry may be difference among the different centrality and and/or

  19. CMS, PRC87(2013)014902 Event-plane Lee-Yang zero point Charged particle in the Pb+Pb collisions at

  20. Predicted charge particle in the p+Au collisions at

  21. Predicted charge particle in the p+Pb collisions at

  22. Predicted charge particle in the p+p collisions at

  23. 5 Conclusions (1) Model parameters are first fitted to the experimental data of charged particle pseudo-rapidity and used in all of the simulations. (2) The calculated charge particle in the Au+Au/Pb+Pb collisions at describe the corresponding experimental data fairly well (3) The charged particle in the p+Au/p+Pb collisions at and in the p+p collisions at are predicted. The elliptic flow parameter in these reactions reaches a measurable amount.

  24. Thanks for your attention！

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