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

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

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

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

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

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

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

7 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

8 geometrical eccentricity of the initial spatial overlap zone

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

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

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

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

13 2 Physical ingredients in PACIAE PACIAE is based on PYTHIA (A) Initiation (i) Distributing nucleons according to Woods Saxon, (iii)spectator nucleons outside OLZ but inside nucleus- nucleus collision system (ii) participant nucleons inside OLZ OLZ y x p T z b

14 (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

15 (B) Parton re-scattering (parton evolution) (C) Parton hadronization with SF or CM (D) Hadron re-scattering coalescence model (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 (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

16 Roughly fitting model parameters to dNch/dy3 The model parameters are all fixed as the same as default Values given in PYTHIA, except the K factor,

17 4 Results of & PHENIX, PRC80 (2003) event-plane 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

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

19 Predicted charge particle in the p+Au collisions at

20 Predicted charge particle in the p+Pb collisions at

21 Predicted charge particle in the p+p collisions at

22 5 Conclusions (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. (1) Model parameters are first fitted to the experimental data of charged particle pseudo-rapidity and used in all of the simulations.

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