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Reduction of Strange Quark Suppression in p-p and A-A Collisions at RHIC and LHC

This study explores the reduction of strange quark suppression and production of strange hadrons in p-p and A-A collisions at RHIC and LHC. The investigation of strange hadron production is crucial for understanding the nature of QGP in heavy-ion collisions. The study includes motivations, PACIAE model, strangeness production mechanisms, and summaries.

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Reduction of Strange Quark Suppression in p-p and A-A Collisions at RHIC and LHC

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  1. Reduction of strange quark suppression and strange hadron production in p-p and A-A collisions at RHIC and LHC Sheng-Qin Feng China Three Gorges University (CTGU) IOPP, Wuhan China

  2. Outline 1、Motivation 2、PACIAE and strangeness production mechanisms 3、strangeness productions of p-p and A-A interactions 4、Summary Based on: Long,HY, Feng, S-Q, Zhou,D-M, Yan, Y-L, Ma H-L and Sa, B-H, Physical Review C 84, 034905 (2011) Ren, X-W and Feng, S-Q, Chinese Physics C 38, 054102 (2014) Ren, X-W and Feng, S-Q submitted to PRC Sa, Ben-Hao et al, Computer Physics Communications 183 (2012) 333–346 IOPP, Wuhan China

  3. 1、Motivation IOPP, Wuhan China

  4. 1、Motivation The investigation of strange hadron productions is an important ingredient in understanding the nature of QGP in relativistic heavy ion collisions . As the strange quark is heavier than up and down quarks, production of strange hadrons is generally suppressed relative to hadrons containing only up and down quarks. The amount of strangeness suppression is an important research topics. IOPP, Wuhan China

  5. LHC new experimental results The differential transverse momentum yields ( spectra) and integrated yields at central rapidity of have been measured by the ALICE experiment during the commissioning phase of the LHC (December 2009) with the very first proton-proton collisions. A sample of 250 k minimum bias pp collisions at sqrt(s)= 0.9 TeV has been selected with triggers combining several fast detectors . Strange particle production in proton-proton collisions at sqrt(s) = 0.9 TeV with ALICE at the LHC. ALICE collaboration, ，Eur.Phys.J.C71,2011:1594, arXiv:1012.3257 Strange Particle Production in pp Collisions at sqrt(s) = 0.9 and 7 TeV,The CMS Collaboration，JHEP 05 (2011) 064 , arXiv:1102.4282 IOPP, Wuhan China

  6. Pb-Pb Collisions at LHC IOPP, Wuhan China

  7. B. Andersson, G. Gustafson, G. Ingelman and T. Sjiistrand, Phys. Rep. 97 (1983) 31. Strangeness suppression As the strange quark is heavier than up and down quarks, production of strange hadrons is generally suppressedrelative to hadrons containing only up and down quarks. Originally, the suppression of s quark pair production compared with u(d) pair production is assumed to be a‘constant’in theLUND string fragmentation scheme (PYTHIA). IOPP, Wuhan China

  8. Strangeness suppression • The mechanism ofreduction of strange quark suppression has been studied in the early paper. • Later experiments during SPS have shown this suppressiondecreases with increasing collision energy. Tai,A and Sa, B-H PLB409(1997)393-397 Sa, B-H and Tai, A, Phys. Rev. C 55 (1997) 2010. IOPP, Wuhan China

  9. Tai,A and Sa, B-H PLB409(1997)393-397 Sa, B-H and Tai, A, Phys. Rev. C 55 (1997) 2010. The effective string tension was introduced in PLB409-393 and assumed it to be increased with increasing reaction energy. Hence the strange quark production increases with increasing reaction energy. It was assumed further that the effective string tension varies with reaction energy can be considered by the effective string tension as a function of the number and hardening of gluons in the string. IOPP, Wuhan China

  10. We use the transport model PACIAE to study the strangeness production in pp collisions: STAR@ ALICE@ CMS@ • Prediction: ALICE@ The relation between K/π ratio and reaction energies. IOPP, Wuhan China

  11. 2、PACIAE and strangeness production mechanisms References: Sa Ben-hao, Zhou Dai-mei, Yan Yu-liang, LI Xiao-mei,Feng Sheng-qin, CAI Xu. Comput. Phys. Commun, 2012,183: 333-346 SA Ben-hao, ZHOU Dai-mei, DONG Bao-guo, YAN Yu-liang, MA Hai-liang, LI Xiao-mei. J. Phys. G: Nucl. Part.Phys., 2009, 36: 025007; Yan Yu-liang, Zhou Dai-mei,Dong Bao-guo, Li Xiao-mei, Ma Hai-liang, Sa Ben-hao.Phys.Rev. C, 2012, 81: 044914; Zhou Dai-mei, Yan Yu-liang, Dong Bao-guo, Li Xiao-mei, Wang Du-juan, CaiXu, Sa Ben-hao. Nucl.Phys. A, 2011, 860: 68 IOPP, Wuhan China

  12. Sketch for pp dynamic simulation (PYTHIA & PACIAE.641) Final state radiation Initial state radiation Remnant 3 h 4 1 p 2 hadron rescattering … h parton distribution function h Decay p h parton rescattering Hadronization Remnant IOPP, Wuhan China

  13. The PACIAE PACIAE is a parton and hadron cascade model which consist of four stages of the parton initiation, parton re-scattering, hadronization,and hadron re-scattering. In the PYTHIA model it is assumed that the pair produce with probability IOPP, Wuhan China

  14. In this work, the dependence of effective string tension on increasing reaction energy introduced in PLB409-393 are used to discussed the strangeness production of p-p collisions in the RHIC and LHC energy regions IOPP, Wuhan China

  15. The PACIAE where is the string tension of the pure string assumed to be 1 ～GeV/fm represents the deviation scale of the multi-gluon string from the pure string. IOPP, Wuhan China

  16. 3、Strangeness productions of p-p and A-A interactions IOPP, Wuhan China

  17. Strange particles rapidity densities at midrapidity (|y| <0.5) in NSD pp collisions at withadj1(31)=0.18(D=0.1), adj1(32)=0.4 (D=0.3), andadj1(33)=0.5(D=0.4). Long,H-Y, Feng, S-Q, Zhou,D-M, Yan, Y-L, Ma H-L and Sa, B-H, Physical Review C 84, 034905 (2011) IOPP, Wuhan China

  18. Transverse momentum distribution of strange particles in NSD(non-single-diffractive) p-p collisions at . Long,HY, Feng, S-Q, Zhou,D-M, Yan, Y-L, Ma H-L and Sa, B-H, Physical Review C 84, 034905 (2011) IOPP, Wuhan China

  19. Strange particle production in proton-proton collisions at sqrt(s) = 0.9 TeV with ALICE at the LHC. ALICE collaboration, ，Eur.Phys.J.C71,2011:1594, arXiv:1012.3257 Strange particles rapidity densities at mid-rapidity in inelastic pp collisions at IOPP, Wuhan China

  20. Transverse momentum distribution of strange particles in INEL pp collisions at . IOPP, Wuhan China

  21. The strange particles rapidity densities at midrapidity in pp collisions at and . IOPP, Wuhan China

  22. The strange particle rapidity distributions in NSD pp collisions at and . IOPP, Wuhan China

  23. The strange particle transverse momentum distributions in NSD pp collisions at and . IOPP, Wuhan China

  24. The PACIAE results at =2.36, 7, and 14 TeV indicate that the K/π ratio as a function of first grows up from 0.2TeV to 0.9TeV and then turns to saturation. IOPP, Wuhan China

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  32. Summary • In summary, these results might indicate the un-negligible effect of the reduction of strange quark suppression mechanism. • Until now, we find that PACIAE can fit well the strangeness productions in RHIC and LHC data. but for the multi-strangeness production, we still need to improve the fit results. IOPP, Wuhan China

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