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Two Freeze-out Model in Relativistic Heavy ion Collisions

Two Freeze-out Model in Relativistic Heavy ion Collisions. Motivation Two freeze-out Model Results Conclusion. Kang Seog Lee ( 전남대 ). HIM 2011.6.10. Motivation. Thermal freeze-out from m t spectra T th. Chemical freeze-out from yields T ch.

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Two Freeze-out Model in Relativistic Heavy ion Collisions

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  1. Two Freeze-out Modelin Relativistic Heavy ion Collisions Motivation Two freeze-out Model Results Conclusion Kang Seog Lee (전남대) HIM 2011.6.10

  2. Motivation Thermal freeze-out from mt spectra Tth Chemical freeze-out from yields Tch Hadron ratios are nicely fitted with statistical model. The slopes of mt spectra are well explained with expanding fireball model when absolute magnitude for each hadron is arbitrary adjusted . Tch> Tth Tch > Tth We want to fit both the yields, the magnitude and slopes of mt spectra of various hadrons measured at RHIC with an expanding fireball model assuming two freeze-outs.

  3. Hydrodynamic equation + Hadronic afterburner • (UrQMD) • - at Tsw, generate hadrons via Monte Carlo Method • Hydrodynamic equation + Partial Chemical • Equilibrium • - below Tch, fix Ni except for short lived resonances ( eg. • Delta) and solve for mui (13x13 matrix) Heinz Hirano

  4. Expanding fireball Model with two freeze-outs Chemical freeze out : Number of each thermal particles is fixed. Nith is fixed. Calculate chemical potential, i of particle i from fixed Nith.  Tch Tth Thermal freeze-out Find thermal freeze out parameters to fit mt spectra using i. Resonance contribution should be included. Hadron yields, slopes and magnitude of mt spectra of various hadrons can be simultaneously explained within a single model.

  5. Model Description Cooper-Frye Formula For an ellipsoidally expanding fireball H. Dobler, J. Sollfrank, U. Heinz, P.L. B457,353(1999)

  6. Chemical analysis Chemical Potential Total Particle Number Thermal analysis Transverse Mass Spectrum Chemical Potential from particle ratios fixed at Tch.

  7. Chemical Freeze-out Result Au+Au 200GeV/A = 153 MeV = 4.7 = 1.2 = 28 MeV = 9.5 MeV = 1.1 = 0.4

  8. Thermal Freeze-out Result = 122.3 MeV = 2.6 = 1.01 = 1.1 = 9674.7 = 3.2

  9. Conclusion • Inan ellipsoidally expanding fireball model, both the yields, magnitude and slopes of the pt spectra at RHIC are described assuming two freeze-outs. 2. Particle pt spectra are nicely fitted without arbitrary normalization. The resulting chemical freeze-out temperature is quite low, Tch – 153MeV. 3. We are waiting for LHC data to analyze.

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