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Heavy Ion Physics at NICA Simulations G.Musulmanbekov, V. Toneev and the Physics Group on NICA

Heavy Ion Physics at NICA Simulations G.Musulmanbekov, V. Toneev and the Physics Group on NICA. Search for signals of Phase Transition in Au + Au collisions at √s NN = 3 – 9 GeV Motivation

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Heavy Ion Physics at NICA Simulations G.Musulmanbekov, V. Toneev and the Physics Group on NICA

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  1. Heavy Ion Physics at NICASimulationsG.Musulmanbekov, V. Toneevand the Physics Group on NICA

  2. Search for signals of Phase Transition in Au + Au collisions at √sNN = 3 – 9 GeV • Motivation • The main goal of the NICA experiment is to study the behaviour of nuclear matter in vicinity of the QCD critical endpoint. • To extract information on the equation-of-state of baryonic matter at high densities. • Search for signals of Phase Transition in Au + Au collisions • at √sNN = 3 – 9 GeV

  3. Search for signals of Phase Transition in Au + Au collisions at √sNN = 3 – 9 GeV • Signatures of Possibile Phase Transition : • Strange particle enhancement • Hard spectrum of strange mesons • Charmonium suppression • Dielectron mass spectrum enhancement at the range 0.2 – 0.6 GeV/c

  4. Search for signals of Phase Transition in Au + Au collisions at √sNN = 3 – 9 GeV • Observables : • Global characteristics of identified hadrons, including strange baryons • Strange to non-strange particles ratio • Transverse momentum spectra • Fluctuations in multiplicity and transverse momenta • Directed and elliptic flows • Particle correlations (femtoscopy, HBT correlations) • Dilepton spectra

  5. Search for signals of Phase Transition in Au + Au collisions at √sNN = 3 – 9 GeV • Simulation Tools : • UrQMD 1.3, UrQMD 2.2 • 104 central events at 3, 3.8, 5, 7, 9 GeV • 105 min bias events at 3, 3.8, 5, 7, 9 GeV • FastMC • 104 central events at 3, 5, 7, 9 GeV • PLUTO • 106 central events at 3, 5, 7, 9 GeV

  6. Mean multiplicities in Au-Au collisions Simulated by UrQMD min.bias events 

  7. Mean multiplicities in Au-Au collisions Simulated by UrQMD central collisions (b ≤ 3 fm) 

  8. Mean multiplicities in Au-Au collisions Simulated by UrQMD central collisions (b ≤ 3 fm) 

  9. Mean multiplicities in Au-Au collisions Simulated by UrQMD central collisions (b ≤ 3 fm) 

  10. Simulated charged multiplicity distributionsin central collisions (b < 3fm)

  11. Simulated charged pseudorapidity distributions in central collisions (b < 3fm)

  12. Simulated charged pseudorapidity distributions in central collisions (b < 3fm) MPD -2 < η < 2

  13. Simulated charged pseudorapidity distributions in central collisions (b < 3fm) MPD -1 < η < 1

  14. Strange Baryons Yield Table: Marked hyperons are accessible through their decays into charged hadrons

  15. Accessible Hyperons

  16. Accessible Hyperons Λ → pπ- Ξ- → Λπ- → pπ- π- Ω- → ΛK- → pK- π-

  17. Strange to non-Strange ratios in central collisions“Horn” Effect <π- >/<π+> Au+Au/Pb+Pb, central <K+ >/<π+> Au+Au/Pb+Pb, central

  18. Strange to non-Strange ratios in central collisions“Horn” Effect

  19. Strange to nonStrange ratios in central collisions

  20. Strange to nonStrange ratios in central collisions

  21. Strange to nonStrange ratios in central collisions

  22. Transverse Mass Spectra of Mesonsin central collisions T – inverse slope

  23. Transverse Mass Spectra of Mesonsin central collisions

  24. Transverse Mass Spectra of Mesonsin central collisions

  25. Scaled multiplicity variances ω (h+) ω (h-) ω (hch)

  26. Scaled multiplicity variancesNA49 results NA49 result: Measured scaled variances are close to the Poisson one – close to 1! No sign of increased fluctuations as expected for a freezeout near the critical point of strongly interacting matter was observed.

  27. Transverse momentum fluctuations To exclude trivial fluctuations from consideration the following variable is used: For the system of independently emitted particles (no inter-particle correlations) Фpt goes to zero.

  28. Directed flow v1 & elliptic flow v2 z x Non-central Au+Au collisions: Interactions between constituents leads to a pressure gradients => spartial asymmetry is converted in asymmetry in momentum space => collective flows - directed flow V2>0 indicates in-plane emission of particles V2<0 corresponds to out-of-plane emission (squeeze-out perpendicular to the reaction plane) - elliptic flow

  29. Direct flowAu + Au collisions at √sNN = 7GeV, b = 5 – 9 fm

  30. Direct flow slopeCollision Energy Dependence Au + Au, b = 5 – 9 fm

  31. Elliptic flowAu + Au collisions at √sNN = 7GeV, b = 5 fm

  32. Elliptic flowCollision Energy Dependence Au+Au/Pb+Pb, b = 5 – 9 fm

  33. HBT interferometry Rlong p1 x1 p2 qside Rside x2 qout qlong Rout • HBT: Quantum interference between identical particles 2 C (q) Gaussian model (3-d): 1 • Final-state effects (Coulomb, strong) also can cause correlations, need to be accounted for q (GeV/c) • Two-particle interferometry: p-space separation  space-time separation Sergey Panitkin

  34. HBT interferometry

  35. HBT interferometry

  36. HBT interferometry

  37. Dilepton Spectra

  38. Dilepton Spectra

  39. Dilepton Spectra

  40. Dilepton Spectra

  41. Dilepton Spectra

  42. Conclusions New simulation codes which take into accountphase transitions of deconfinement and/or chiral symmetry restoration are needed.

  43. Thank you!

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