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A Blast-wave Model with two Freeze-outs

A Blast-wave Model with two Freeze-outs. Motivation A Blast-wave model with two freeze-outs Results Conclusion. Kang Seog Lee ( 전남대 ). HIM 2011.12.10. Chemical analysis of hadron ratios. Thermal analysis of mt spectra of hadrons.

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A Blast-wave Model with two Freeze-outs

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  1. ABlast-wave Model with two Freeze-outs • Motivation • A Blast-wave model with two freeze-outs • Results • Conclusion Kang Seog Lee (전남대) HIM 2011.12.10

  2. Chemical analysis of hadron ratios Thermal analysis of mt spectra of hadrons

  3. At Tch, chemical freeze-out occurs if inelastic collisions, which makes A+B->C+D, are not abundant. Then the numbers of each species, A,B,C, and D are not changing. At Tth, thermal freeze-out occurs if elastic collisions are not abundant. Then, the momentum distribution is not changing any more. Earlier chemical freeze-out and later thermal freeze-out.

  4. Models to incorporate the fact that • in explaining the hadron production • Hydrodynamic equation + Hadronic afterburner • (UrQMD) • - at Tsw, generate hadrons via Monte Carlo Method • Hydrodynamic equation + Partial Chemical • Equilibrium (PCE) • - below Tch, fix Ni except for short lived resonances • ( eg. Delta) and solve for mui (13x13 matrix) Bass, Heinz+Bass Hirano, Teaney

  5. A Blast-wave model with two freeze-outs Suk Choi, KSLee, PRC84, 064905(2011) • Chemical analysis at Tch • – Lorentz boosted thermal distribution is used. • Tch<T<Tth, number of thermal hadrons of each hadron species fixed. • Approximation: Treat short lived hadrons as long lived ones, which causes small error but calculation becomes much simpler and fast. • At Tth, thermal analysis of mt spectra • Resonance contribution is carefully treated.

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

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

  8. Results of chemical analysis Tch=173.9 MeV mB=26.4 MeV ms=6.0 MeV gs=1.01 c2/n=0.12 Tch=173.4 MeV mB=18.5 MeV ms=7.9 MeV gs=0.986 c2/n=1.4 Weak decay contribution is properly included.

  9. Result of thermal analysis Tth=121.1 MeV mp-=126.4 MeV hmax=5.0 r0=1.03 gs=0.986 c2/n=5.3

  10. rapidity distribution dNch / dy Tth=121.1 MeV mp-=126.4 MeV hmax=5.0 r0=1.03 gs=0.986

  11. Conclusion • Withinan expanding fireball model assuming two freeze-outs, both the yields, the magnitudes and slopes of the pt spectra, and y-distribution of charged hadrons measured at RHIC are described. 2. Hadron ratios, mt spectra of pions, kaons and protons, and rapidity distribution of total charged hadrons are nicely fitted. Resonance contribution is important. For mt spectra, we have only one overall constant. Wide width of rapidity distribution is also nicely fitted by eta_max. 3. We are waiting for LHC data to analyze.

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