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Assembling an Elephant: Recent RHIC Results in Context

Explore the connections and big picture behind recent RHIC results, including topics like lattice physics, pQCD, deconfinement, jets, and more. Highlight the geometry behavior of bulk chemistry, Glauber models, and the Woods-Saxon nuclear density distributions.

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Assembling an Elephant: Recent RHIC Results in Context

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  1. Assembling an Elephant:Recent RHIC Results in Context David Morrison BNL Physics Dept. Katushika Hokusai (1760-1849)

  2. “Encyclopedia“ of RHIC results growing quickly Spans a slew of physics lattice, CGC, pQCD, hydro, hadronic gas, jets, deconfinement, etc. Run 4 (Au+Au) and Run 5 (Cu+Cu) added large datasets and extended physics reach of all experiments Take a few recent results and try to show their connections

  3. the big picture: geometry behavior of the bulk chemistry

  4. Glauber* models Woods-Saxon nuclear density distributions Straight line nucleon trajectories Variety of ways to make correspondence with exp’t *Would be better to call our approach “Glauber-inspired” PHOBOS Glauber MC Roy Glauber, meet ... Alfred Nobel

  5. >99.5% PHOBOS 200 GeV Au+Au charged hadrons D. Hofman (Moriond ‘04)

  6. Total charged particle production 62.4 GeV 200 GeV PHOBOS Here: number of participants  100 G. Roland (QM’05)

  7. Boost invariant? BRAHMS 200 GeV Au+Au dn/dy Bjorken rapidity, y (not pseudorapidity, ) energy density estimate: 5 GeV/fm3 Landau

  8. Chemically equilibrated

  9. If it’s really matter then it should radiate. In particular, it should radiate photons. David Morrison

  10. photons photons from hadronic decays (0, , ...) direct photons photons emitted by thermalized system prompt photons from initial parton-parton collisions

  11. Decay photons What would one expect? S. Bathe (QM’05) David Morrison

  12. (possibly) Thermal virtual photons e- Y. Akiba (QM’05)

  13. ratios in different Mee bins; calculable from Dalitz formula excess attributed to direct photons results in lowered systematic error compared to conventional approach in this pT range Looking for direct photons David Morrison

  14. low pT above NLO pQCD • L.E.Gordon and W. Vogelsang Phys. Rev. D48, 3136 (1993) • high pT above thermal model • D. d’Enterria, D. Perresounko nucl-th/0503054 2+1 hydro T0ave=360 MeV (T0max=570 MeV) t0=0.15 fm/c • data consistent with thermal + pQCD S. Bathe (QM’05)

  15. z y x Collective phenomena An idea with some history: Ann. Phys. 6, 1 (1959) PRL 32, 741 (1974) David Morrison

  16. range of opinions regarding momentum space consequences, at RHIC energies, of initial asymmetry if the QGP were a gas of free quarks and gluons, you wouldn’t expect strong effects it’s not a gas of free quarks and gluons, apparently Elliptic flow azimuthally asymmetric initial geometry

  17. BNL Physics Dept. colloquium by Ken O’Hara (Penn. St.) nano-Kelvin gas of 6Li atoms magnetic trap tunable Feschbach resonance small scattering length leads to viscous hydrodynamics isotropic expansion when trapping field dropped Isotropic expansion

  18. Feshbach resonance tuned for large scattering length nearly ideal hydrodynamics anisotropic expansion when trapping field dropped Anisotropic expansion

  19. A v Dx Perfect fluid? Hydrodynamic flow in idealized case is isentropic: no entropy growth P. Stankus

  20. Entropy grows Volume and velocity are constant, so power heats fluid, generating entropy The fractional rate of increase in entropy is proportional to /s; the smaller this is, the smaller the increase in entropy, and the closer to “perfect” the fluid is.

  21. Low viscosity or high entropy? sQGP is viscous, but its high entropy density compensates Gyulassy, Hirano nucl-th/0506049

  22. Flow of identified particles Hydro: P. Huovinen, priv. comm. (2004) M. Oldenburg (QM’05)

  23. Momentum anisotropy to high pT geometry-driven momentum anisotropy geometry-driven emission anisotropy

  24. Partonic flow? Consistent with a picture of flow being largely established at partonic level M. Oldenburg (QM’05)

  25. Au+Au Cu+Cu PHOBOS preliminary Elliptic flow in Au+Au and Cu+Cu G. Roland (QM’05)

  26. central Ncoll = 975  94

  27. Quantifying the nuclear effect yield in A+A/number of equivalent p+p collisions RAA = yield in p+p

  28. GLV energy density estimate: 15 GeV/fm3 geometry-limited energy loss

  29. charm yield determined from single electron spectrum charm decay dominant source of intermediate pT electrons not only very high pT but also very heavy quarks lose tremendous energy trying to escape system: very opaque And charm is suppressed too David Morrison

  30. Back to back jets (di-jets) single particle spectra tell you a lot, but you should be able to learn even more from di-jets

  31. 1 dN Ntrig d Studying jets through correlations flow+jet flow A strong connection between two topics that seem very different: dijets and flow jet CF = J(Df) + l(1+2v2tv2a cos2Df) J. Jia (BNL Seminar) David Morrison

  32. Pedestal&flow subtracted same direction opposite direction intensity angle away from initial high momentum particle

  33. STAR J. Dunlop

  34. STAR 8 < pT(trig) < 15 GeV/c pT(assoc) > 6 GeV J. Dunlop

  35. What happens to a fast parton? one idea is that it might generate a shock wave and emit radiation at a characteristic angle that depends on cs (the speed of sound in the medium) ... or, that there would be Cerenkov radiation of gluons ... or, that it is deflected in the dense, flowing medium Casalderrey-Solana, Shuryak and Teaney, hep-ph/0411315 Koch, Majumder, X.-N. Wang, nucl-th/0507063 David Morrison

  36. Jet shape vs centrality PHENIX preliminary J. Jia David Morrison

  37. Jet shape vs centrality PHENIX preliminary J. Jia David Morrison

  38. D D Jet shape vs centrality PHENIX preliminary J. Jia Near side : broadening, Away side: splitting

  39. A. Adare

  40. 3 (or more) particle correlations David Morrison

  41. 2 A–C C 0 A B A–B 0 2

  42. 3-particle cumulant: subtract off lower order correlations Au+Au 10% difference in Au+Au average signal per radian2: center – corner = 0.3 ± 0.3 (stat) ± 0.4 (syst) center – cone = 2.6 ± 0.3 (stat) ± 0.8 (syst) J. Ulery (QM’05) David Morrison

  43. Summary and outlook • many great results so far • further analysis needed • more statistics needed • closer involvement of theorists

  44. Better summary • geometry drives the bulk behavior • collective phenomena are both great complication and a great boon to analyses • high pT hadrons, dijets, photons, heavy quarks are all living up to their promise as probes of created matter • ... and we already have good interactions with theory community

  45. hard probes geometry hydro collective phenomena David Morrison

  46. Changing the geometry both cases: 100 participants different ellipticity odd harmonics Cu+Au Au+Au

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