| Azimuthal Anisotropy and the QGP |
| Yasuo MIAKE, Univ. of Tsukuba |
| Reasons why I love azimuthal anisotropy |
| Info. on mean free path l vs. R | |||
| Anisotropy of the coordinate space converted to that of the momentum space. | |||
| Clear origin of the signal ! | |||
| Geometry is clear | |||
| From eccentricity to v2 | |||
| Centrailty dependence gives good tests | |||
| Sensitivity to the early stage of collisions ! | |||
| Sensitivity to the early stage |
| Anisotropy in coordinate space disappears quickly | ||
| Ratio of eccentricity after a time delay | ||
| Disappears quickly | ||
| è v2 senses early stage of collision | ||
| Key1; reliable R.P. determination |
| Wide rapidity gap from central detector | ||
| Free from other source of corr such as HBT, decays, jets & auto-corr. | ||
| Corr. between SMD(spect) and BBC(part) also confirmed | ||
| →R.P. determination from whole event wide | ||
| Key2; PID with TOF & Aerogel |
| High resolution TOF and low index of 1.01 Aerogel Cherenkov | ||
| Both Tsukuba contribution | ||
| What we expected before RHIC |
| There is a tendency of saturation!? | |
| Hadron cascade predicts a few %. |
| Surprise ! |
| Early compilation |
| Large azimuthal anisotropy |
| Larger in higher energies. | |
| Increase with pt and saturate |
| Failure of hadronic scenarios |
| Hadronic scenario underestimates v2 at RHIC. | ||
| v2 ~ 1 - 2 % | ||
| System thermalized early with the mechanism other than hadronic rescatterings. | ||
| v2 vs. Eccentricity |
| At low pt region, the ratio stays ~constant | ||
| Eccentricity scaling observed in comparison of Au+Au, Cu+Cu | ||
| èScaling with eccentricity shows v2 builds up at early stage | ||
| v2 with particle identification |
| Low pt region; | ||||
| v2(p) > v2(K) > v2(p) | ||||
| Mass Ordering | ||||
| Good agreement with hydrodynamics | ||||
| Very early thermalization (0.6 fm/c) & high energy density (~20 GeV/fm3) required ! | ||||
| èMore from Hirano’s talk | ||||
| Perfect fluid (low viscous) | ||||
| What brings the system thermalization in such a short time! | ||||
| èPartonic degree of freedom | ||||
| Deviations at high pt region (> 1.5 GeV/c); |
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| v2(p,K) < v2(p) | ||||
| Meson vs Baryon? | ||||
| Other mechanism? | ||||
| Mass Ordering in single spectra |
| Exponential in mt for low pt region | ||
| Known from AGS & SPS era | ||
| Mass ordering of slope parameters | ||
| Proof of hydrodynamical collective flow | ||
| Other surprise; baryon dominance |
| We had many reasons to consider > 2GeV/c is the jet region. | ||
| In peripheral, p/p ratio similar to those in ee/pp suggesting fragmentaton process. | ||
| Fragmentation process should show np < np as seen in ee/pp. | ||
| In central Au+Au, p/p ratio increases with centrality, suggesting other mechanism. | ||
| Quark recombination model (RECO) |
| Quarks, anti-quarks combine to form mesons and baryons from universal quark distribution, w(pt). |
| Proton dominance by RECO |
| Recombination model explains the proton dominance. |
| V2 from RECO |
| Characteristic scaling behavior |
| Quark number scaling observed! |
| Quark number scaling clearly observed in v2. | |
| Distinct difference between Baryon
Meson also seen in RCP, yield ratio of central and peripheral coll. |
| Mass ordering of quarks? |
| Accidental OR ordering in mass of quarks? | ||
| Existence of hypersurface where QGP converted to hadrons? | ||
| Study of electron for charm |
| Origins of electrons | |||
| “photonic” | |||
| Dalitz decays of p0,h,r,w, | |||
| Photon conversions | |||
| “non-photonic” | |||
| Semi-leptonic decays of heavy flavored mesons | |||
| èElectron yields are consistent with those photonic + charm decays. | |||
| Charm v2 from electrons |
| Measure v2 of inclusive electrons | ||
| Evaluate contribution of photonic electron | ||
| Cocktail Method | ||
| Converter Method | ||
| Then, subtract ! | ||
| Charm seems to flow! |
| Data seem to favor the flow of the charm. | |
| If so, thermalized & flowing charm supports quark-coalescence & formation of QGP. |
| Study of direct photon |
| Pi-zero results consistent with other mesons | ||
| No significant diff. btwn inclusive v2 and expected photon v2 from hadronic decay (pion, eta, etc) | ||
| Direct photons are from compton-like “prompt” process? | ||
| Summary of my talk |
| v2 is fun! | |||
| Establishment of R.P. is great ! | |||
| v2 is even useful ! | |||
| Sensitive to the early stage of collisions | |||
| Thermalization as early as 0.6 fm/c | |||
| Large azimuthal anisotropy cannot be generated with hadronic process. | |||
| Support the quark recombination model | |||
| Collectivity at parton level | |||
| Phenomenological, but universal quark distribution function! | |||
| èstatistical description of quarks èQGP | |||
| Much fun to come | |||
| Charm & photon ! | |||