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HIJING Model Validation at RHIC Energies V.Uzhinsky (JINR, Dubna)

Preamble. HIJING Model Validation at RHIC Energies V.Uzhinsky (JINR, Dubna). HIGING model is widely used for simulation of AA-interactions at RHIC and LHC energies. There are a lot of new RHIC data, but there is no suggestions for changing of the model parameters.

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HIJING Model Validation at RHIC Energies V.Uzhinsky (JINR, Dubna)

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  1. Preamble HIJING Model Validation at RHIC EnergiesV.Uzhinsky (JINR, Dubna) • HIGING model is widely used for simulation of AA-interactions at RHIC and LHC energies. • There are a lot of new RHIC data, but there is no suggestions for changing of the model parameters. • Status of model at RHIC is unknown. Is it well, or is it bad? • How many particles are produced by QGP? • Which interactions produce QGP? And so on … Contents • HIJING model description of PHOBOS data • Tuning of model parameters • Conclusion

  2. HIJING model description of PHOBOS data Au+Au-interactions at 200 GeV, B. B. Back et al.,Phys. Rev. Lett. 91 (2003) Pseudo-rapidity distributions of charged particles in AuAu interactions at 200 GeV as a function of collision centrality. Standard HIJING calculations.

  3. HIJING model description of PHOBOS data Au+Au-interactions at 200 GeV, Invariant yield of charged hadrons. Standard HIJING calculations. Too strong jet quenching? B. B. Back et al.,Phys. Lett. B578 (2004).

  4. HIJING model description of PHOBOS data Au+Au-interactions at 200 GeV, Invariant yield of charged hadrons at small Pt. Standard HIJING calculations. Too many low Pt particles due to jet quenching? B. B. Back et al.,Phys. Rev. C70 (2004) 051901

  5. HIJING model description of PHOBOS data dAu-interactions at 200 GeV, B. B. Back et al., Pseudo-rapidity distributions of charged particles in dAu interactions at 200 GeV as a function of collision centrality. Standard HIJING calculations.

  6. HIJING model description of PHOBOS data dAu-interactions at 200 GeV, B. B. Back et al.,Phys. Rev. Lett. 91 (2003) Why there is suppression? There is no jet quenching in the interactions! Invariant yield of charged hadrons, (h++h-)/2, as a function of pT for four centrality bins. Standard HIJING calculations.

  7. HIJING model description of PbarP data Take attention on the discrepancies between data and model calculations in the Pt region 1-2 GeV/c! Invariant yield of charged hadrons, (h++h-)/2, as a function of pT. Standard HIJING calculations.

  8. Tuning of model parameters COMMON/HIPARNT/HIPR1(100), IHPR2(50), HINT1(100), IHNT2(50) HIPR1(1): (D=1.5 GeV/c2) minimum value for the invariant mass of the excited stringsystem in a hadron-hadron interaction. HIPR1(2): (D=0.35 GeV) width of the Gaussian PT distribution of produced hadron inLund string fragmentation (PARJ(21) in JETSET 7.2). HIPR1(8): (D=2.0 GeV/c) minimum PT transfer in hard or semihard scatterings. HIPR1(9): (D=−1.0 GeV/c) maximum PT transfer in hard or semihard scatterings. Ifnegative, the limit is set by the colliding energy. HIPR1(19),HIPR1(20): (D=0.1, 1.4 GeV/c) parameters in the distribution for the PT kickfrom soft interactions (see Eq. 23), 1/[(HIPR1(19)**2 + PT**2 )(HIPR1(20)**2 + PT**2 )]. HIPR1(21): (D=1.6 GeV/c) the maximum PT for soft interactions, beyond which a Gaussiandistribution as specified by HIPR1(2) will be used.

  9. Tuning of model parameters Now the calculations underestimate the exp. data at low Pt for 200 GeV. For 900 GeV all O.K.. Invariant yield of charged hadrons, (h++h-)/2, as a function of pT.

  10. Tuning of model parameters dAu-interactions at 200 GeV, B. B. Back et al.,Phys. Rev. Lett. 91 (2003) Invariant yield of charged hadrons, (h++h-)/2, as a function of pT for four centrality bins. Only statistical errors are shown for experimental points.

  11. Tuning of model parameters dAu-interactions at 200 GeV, B. B. Back et al., Pseudo-rapidity distributions of charged particles in dAu interactions at 200 GeV as a function of collision centrality.

  12. Tuning of model parameters Au+Au-interactions at 200 GeV, Invariant yield of charged hadrons. Turning off the jet quenching gives the main effect! B. B. Back et al.,Phys. Lett. B578 (2004)

  13. HIJING model description of PHOBOS data Au+Au-interactions at 200 GeV, Invariant yield of charged hadrons at small Pt. B. B. Back et al.,Phys. Rev. C70 (2004) 051901

  14. Tuning of model parameters Au+Au-interactions at 200 GeV, B. B. Back et al.,Phys. Rev. Lett. 91 (2003) Now the discription is not satisfactory. Pseudo-rapidity distributions of charged particles in AuAu interactions at 200 GeV as a function of collision centrality.

  15. Tuning of model parameters HIPR1(2) is connected with Pt kick of valence quark and Pt of hadrons at string fragmentation. It is not good. SUBROUTINEHIJSET(EFRM,FRAME,PROJ,TARG,IAP,IZP,IAT,IZT) PARJ(21)=HIPR1(2) SUBROUTINEATTRAD(IERROR) IF(PTG.GT.HIDAT(2)) THEN FMFACT=EXP(-(PTG**2-HIDAT(2)**2)/HIPR1(2)**2) IF(RAN(NSEED).GT.FMFACT) GO TO 1 ENDIF SUBROUTINEHIJSFT(JP,JT,JOUT,IERROR) IF(IHPR2(5).EQ.0) THEN PKC=HIPR1(2)*SQRT(-ALOG(1.0-RAN(NSEED) & *(1.0-EXP(-PKCMX**2/HIPR1(2)**2)))) GO TO 30 ENDIF IF(PKC.GT.HIPR1(20)) & PKC=HIPR1(2)*SQRT(-ALOG(EXP(-HIPR1(20)**2/HIPR1(2)**2) & -RAN(NSEED)*(EXP(-HIPR1(20)**2/HIPR1(2)**2)- & EXP(-PKCMX**2/HIPR1(2)**2))))

  16. Tuning of model parameters Now we treat Pt kick of valence quark and Pt of produced hadrons separately. We have a good description of the data at 200 and 900 GeV. Invariant yield of charged hadrons, (h++h-)/2, as a function of pT.

  17. Tuning of model parameters dAu-interactions at 200 GeV, B. B. Back et al.,Phys. Rev. Lett. 91 (2003) Last calculations = No jet quenching + HIPR1(2)=0.35 + PARJ(21)=0.42 Invariant yield of charged hadrons, (h++h-)/2, as a function of pT for four centrality bins. Only statistical errors are shown for experimental points.

  18. Tuning of model parameters dAu-interactions at 200 GeV, B. B. Back et al., Pseudo-rapidity distributions of charged particles in dAu interactions at 200 GeV as a function of collision centrality.

  19. Tuning of model parameters Au+Au-interactions at 200 GeV, Invariant yield of charged hadrons B. B. Back et al.,Phys. Lett. B578 (2004)

  20. HIJING model description of PHOBOS data Au+Au-interactions at 200 GeV, Invariant yield of charged hadrons at small Pt. Standard HIJING calculations. B. B. Back et al.,Phys. Rev. C70 (2004) 051901

  21. Tuning of model parameters Au+Au-interactions at 200 GeV, B. B. Back et al.,Phys. Rev. Lett. 91 (2003) Pseudo-rapidity distributions of charged particles in AuAu interactions at 200 GeV as a function of collision centrality.

  22. Description of PHENIX data pp-interactions at 200 GeV, S. S. Adler et al., Phys. Rev. Lett. 91 (2003) HIJING model calculations The invariant differential cross section for inclusiveπ0production andtheresultsfrom NLO pQCD calculations with equal renormalizationand factorization scales of pT using the ‘‘Kniehl-Kramer-Po¨tter’’ (solid line) and ‘‘Kretzer’’ (dashed line) sets of fragmentationfunctions.

  23. Description of PHENIX data dAu-interactions at 200 GeV, S. S. Adler et al., Phys. Rev. Lett. 91 (2003) Midrapidity Ptspectra for charged hadrons and π0.

  24. Description of PHENIX data AuAu-interactions at 200 GeV, S. S. Adler et al., Phys. Rev. Lett. 91 (2003) Midrapidity Pt spectra for π0.

  25. Conclusion • After tuning of the model parameters and options we have a reasonable description of: • Charged particles pseudo-rapidity distributions; • Charged particles Pt distributions; • Yields of π+, π-, K+, K- in dAu- and AuAu interactions at RHIC energies. • There is a problem with proton spectra description. • Jet quenching algorithm should be improved in the HIJING program. SUBROUTINE HIJSET(EFRM,FRAME,PROJ,TARG,IAP,IZP,IAT,IZT) PARJ(21)=0.42 ! HIPR1(2) ! Uzhinsky

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