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Mass ordering of differential elliptic flow and its violation for f mesons

Mass ordering of differential elliptic flow and its violation for f mesons. Tetsufumi Hirano Dept. of Physics, The Univ. of Tokyo. Collaborators: U.Heinz, D.Kharzeev, R.Lacey, and Y.Nara. Matsumoto, Feb. 10-11, 2007. Outline. “ Dissipative ” effects on final p T spectra and elliptic flow

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Mass ordering of differential elliptic flow and its violation for f mesons

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  1. Mass ordering of differential elliptic flow and its violation for f mesons Tetsufumi Hirano Dept. of Physics, The Univ. of Tokyo Collaborators: U.Heinz, D.Kharzeev, R.Lacey, and Y.Nara Matsumoto, Feb. 10-11, 2007

  2. Outline • “Dissipative” effects on final pT spectra and elliptic flow • Mass ordering of v2(pT) and its violation for f mesons • Nuclear modification factor for f mesons

  3. Motivation To understand the QGP in H.I.C., need to understand the hadronic stage since Indispensable to disentangle these effects for understanding unknowns.

  4. How Large Hadronic Rescattering? • Hybrid Model: QGP Fluid + Hadronic Gas + Glauber I.C. • Hydro Model: QGP Fluid + Hadronic Fluid + Glauber I.C. ComparisonTry to draw information on hadron gas • Key technique in hydro: • Partial chemical equilibrium in hadron phase • Particle ratio fixed at Tch • Chemical equilibrium changes dynamics. TH and K.Tsuda(’02),TH and M.Gyulassy(’06)

  5. Hydro ~ Hydro+Cascade for Protons • Tth ~ 100 MeV • Shape of spectrum changes due to radial flow rather than hadronic dissipation for • protons. radial flow

  6. Opposite Behaviors for Pions Green line: Teaney(’03) Caveat: Transverse expansion Non-scaling solution Harder: Hadronic Gas (Viscous pressure) Softer: Hadronic Fluid (pdV work)

  7. Source Function from 3D Hydro + Cascade How much the source function differs from ideal hydro in Configuration space? Blink: Ideal Hydro, Kolb and Heinz (2003) Caveat: No resonance decays in ideal hydro Chem.eq. is assumed in ideal hydro.

  8. Hadronic Dissipation Suppresses Differential Elliptic Flow Difference comes from dissipation only in the hadron phase • Relevant parameter: Gs/t • Teaney(’03) • Dissipative effect is not so • large due to small expansion • rate (1/tau ~ 0.05-0.1 fm-1) Caveat: Chemically frozen hadronic fluid is essential in differential elliptic flow. (TH and M.Gyulassy (’06))

  9. v2(h) fromQGP Hydro + Hadronic Cascade Suppression due to hadronic dissipation

  10. Excitation Function of v2 • Hadronic Dissipation • is huge at SPS. • still affects v2 at RHIC. • is almost negligible at LHC.

  11. Mass Ordering of Differential Elliptic Flow and Its Violation for f mesons

  12. pT spectra for pi, K, and p Reasonable reproduction of yields and spectra in low pT region  Non trivial!!!

  13. v2(pT) for pi, K, and p Due to fluctuation of geometry OK!

  14. Origin of Mass Ordering • Mass ordering behavior • comes from hadronic • rescattering. • Not a direct signal of “perfect fluid QGP”

  15. What happens to strangeness sector?

  16. Additive Quark Model in Transport Code (JAM/RQMD/UrQMD) For cross sections without exp. data, Expected to be very smaller for phi, Omega, etc.

  17. Distribution of Freeze-Out Time

  18. f-meson case Just after hadronization Final results T = Tsw = 169 MeV in pT < 1 GeV/c

  19. pT spectra for f mesons It may be dangerous to fit spectra in the whole pT region to obtain freezeout temperature.  pT ~< 1.5 GeV/c ?

  20. Nuclear Modification Factor Non-trivial RAA for f mesons Don’t ask me why K=4.5 for phi mesons!

  21. Summary • Hadronic rescattering effects • Change of spectral shape • Suppression of v2 • Reproduction of v2(pT) • Origin of mass ordering of v2(pT) • Violation of mass ordering for phi mesons • Non-trivial behavior of RAA for phi mesons

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