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Geometry-driven physics at RHIC A work in progress

Geometry-driven physics at RHIC A work in progress. Mike Lisa The Ohio State University. Similar but somehow different…. Geometry-driven physics at RHIC A work in progress. Reminder: what are we doing, and why? Soft / firm / hard What could we see? What do we see? What’s next? Summary.

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Geometry-driven physics at RHIC A work in progress

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  1. Geometry-driven physics at RHICA work in progress Mike Lisa The Ohio State University Warsaw University Faculty of Physics Seminar - malisa

  2. Similar but somehow different… Warsaw University Faculty of Physics Seminar - malisa

  3. Geometry-driven physics at RHICA work in progress • Reminder: what are we doing, and why? • Soft / firm / hard • What could we see? • What do we see? • What’s next? • Summary Mike Lisa The Ohio State University Warsaw University Faculty of Physics Seminar - malisa

  4. PHOBOS BRAHMS RHIC PHENIX STAR Nuclear Particle AGS TANDEMS 1 km v = 0.99995c Warsaw University Faculty of Physics Seminar - malisa

  5. Nuclear Particle …why study condensed matter physics? Even while atoms remain under study… Why heavy ion collisions? Much simpler systems (p+p) under study… …why on earth study A+A? R.H.I.C. physics = partonic condensed matter physics even more fundamental than electronic C.M. physics • Bulk systems: • rich new phenomena of fundamental importance • access physics domains not accessible in small systems • (connection between simple and bulk systems nontrivial & theoretically intractable) Warsaw University Faculty of Physics Seminar - malisa

  6. The real issue… • What happens when nuclei collide? • important for experiment design • (also, it’s fun to study in detail!) • otherwise, who cares? The real issue is… • Can we use them to make a new type of matter in the lab? Warsaw University Faculty of Physics Seminar - malisa

  7. 11 Physics Questions for the New Century • What is dark matter? • What is dark energy? • How were the heavy elements from iron to uranium made? • Do neutrinos have mass? • Where do ultra-energy particles come from? • Is a new theory of light and matter needed to explain what happens at very high energies and temperatures? • Are there new states of matter at ultrahigh temperatures and densities? • Are protons unstable? • What is gravity? • Are there additional dimensions? • How did the Universe begin? • What is dark matter? • What is dark energy? • How were the heavy elements from iron to uranium made? • Do neutrinos have mass? • Where do ultra-energy particles come from? • Is a new theory of light and matter needed to explain what happens at very high energies and temperatures? • Are there new states of matter at ultrahigh temperatures and densities? • Are protons unstable? • What is gravity? • Are there additional dimensions? • How did the Universe begin? The February 2002 issue of Discover magazine based its cover story on the recent 105-page public draft of the National Research Council Committee on Physics of the Universe report, Connecting Quarks with the Cosmos RHIC-I obsession “propaganda” reminiscent of lower s HI program Warsaw University Faculty of Physics Seminar - malisa

  8. quark-gluon plasma critical point ? Tc colour superconductor Temperature hadron gas nucleon gas nuclei CFL r0 baryon density The real issue… • What happens when nuclei collide? • important for experiment design • (also, it’s fun!) • otherwise, who cares? • Can we use them to make a new type of matter in the lab? • important for accelerator design • important for propaganda • in itself: who cares? The real issue is… • What are the properties of this new state of matter? (T, P, , …) Warsaw University Faculty of Physics Seminar - malisa

  9. quark-gluon plasma critical point ? Tc colour superconductor Temperature hadron gas nucleon gas nuclei CFL r0 baryon density The real issue… • What happens when nuclei collide? • important for experiment design • (also, it’s fun!) • otherwise, who cares? • Can we usethem to make a new type of matter in the lab? • important for accelerator design • important for propaganda • in itself: who cares? • What are the properties of this new state of matter? (T, P, , …) • important for analysis design • in itself: who cares? The real issue is… • … to use the QGP to understand hadronization / mass generation Warsaw University Faculty of Physics Seminar - malisa

  10. The real issue… • What happens when nuclei collide? • important for experiment design • (also, it’s fun!) • otherwise, who cares? • Can we usethem to make a new type of matter in the lab? • important for accelerator design • important for propaganda • in itself: who cares? • What are the properties of this new state of matter? (T, P, , …) • important for analysis design • in itself: who cares? We are now around here Original motivation & a focus of RHIC-II The real issue is… • QGP as calibrated tool to understand hadronization / mass generation must go beyond “partonic condensed matter” Warsaw University Faculty of Physics Seminar - malisa

  11. Can we do the same at RHIC? scattered electron incoming electron (controlled probe) Discovery and Properties: The Ideal Experiment The first exploration of subatomic structure was undertaken by Rutherford at Manchester in 1909 using Au atoms as targets and a particles as probes. NO QGP But we can get close ……… Warsaw University Faculty of Physics Seminar - malisa

  12. p+p sNN=200 GeV PHENIX PRL 91 241803 (2003) Fast Partons (Quarks & Gluons) Traversing Matter hadrons • Jets: • high-pT parton produced in a hard (high-Q) scattering process • Calculable in QCD (at high-pT) • partons fragment into many correlated white hadrons • emitted in a cone • created early in the collision quark quark hadrons leading particle (highest-p particle) Warsaw University Faculty of Physics Seminar - malisa

  13. Fate of jets in heavy ion collisions? idea: p+p collisions @ same sNN = 200 GeV as reference p p ?: what happens in Au+Au to jets which pass through medium? ? Au+Au Warsaw University Faculty of Physics Seminar - malisa

  14. b = 0  “central collision” many particles produced “peripheral collision” fewer particles produced Impact parameter & Reaction plane (esp impt for AA) Reaction plane: (b) x (beam) anisotropic “participant zone” b |b| > 0 Warsaw University Faculty of Physics Seminar - malisa

  15. 200 GeV 0 RAA PHENIX (& all others): PRL 2003 Nuclear overlap model to calculate # incoherent NN collisions (no shadowing etc) RAA = (# seen in nuclear collision) / (# expected) (PHENIX notation: f=centrality cut) The Ubiquitous RAA… Mike Lisa: remember all the jubulant press conferences last summer… (Wow, was it really only last summer? I feel like I’ve seen this data for 100 years…) 5x fewer high pT particles than “expected” in AuAu • Common wisdom: • d-Au null result  final state effect • so obvious that initialdAu = AuAu? • look at other hard probes from same initial processes, but withno final state effects… Warsaw University Faculty of Physics Seminar - malisa

  16. Hard non-mesonic (“direct”) photons & non-photonic (“charming”) electrons • Created in earliest, hardest parton scatterings & conserved thereafter • binary scaling √ • (probably some Cronin inside errors) • probe-once-created and creation itself in AA are “calibrated” (better than d-Au) PHENIX QM04 NB: pT-integrated PHENIX 2004 Warsaw University Faculty of Physics Seminar - malisa

  17. 200 GeV 0 RAA Important result! Several complicated (& diff) ways to get suppression? Several canceling effects? Look closer in a more natural way… PHENIX (& all others): PRL 2003 The Ubiquitous RAA… 5x fewer high pT particles than “expected” in AuAu • Common wisdom: • d-Au null effect  final state effect • so obvious that initialdAu = AuAu? • look at other hard probes from same initial processes, but withno final state effects… • Common wisdom II: • final state effect is energy loss incolor-charge-dense(not necc. deconfined) medium •  = 15 GeV/fm3 @  = 0.2 fm • ~ consistent w/ BJ and hydro… Warsaw University Faculty of Physics Seminar - malisa

  18. If we are looking at energy loss… …why quantify downward shift of spectrum (as in RAA)? It seems more natural to quantify leftward shift. [Tannenbaum/Mioduzewski] • NB: ignores • Cronin (see jets() coming up…) • mods in FF (logical to look at shift of partons not their fragments) PHENIX PRL 2003 Warsaw University Faculty of Physics Seminar - malisa

  19. …then let’s look at energy loss Empirical energy loss Tannenbaum/Mioduzewski Warsaw University Faculty of Physics Seminar - malisa

  20. Initial pathlength dependence seems to work • Gyulassy, Vitev, Wang: • 1D expansion, simple geometric scaling • Well reproduced by experimental data. PHENIX prelim Au+Au √sNN=200 GeV Warsaw University Faculty of Physics Seminar - malisa

  21.  (deg) Vary pathlength another way… qualitatively OK, now see about consistency… PHENIX prelim Au+Au √sNN=200 GeV PHENIX B. Cole, HardProbes 04 Warsaw University Faculty of Physics Seminar - malisa

  22. Quantitative consistency required to claim “jet tomography” • Next level of precision needed to clarify underlying quenching mechanism • also -tagging, charm/dead-cone, q/g jet selection, correlated quenching signal versus length • (Role of dynamics in differential analysis may be significant) • cannot just put by-hand some energy loss & find consistency w/BJ No universal loss versus density path? PHENIX preliminary Overlap integral: 1D expansion pT > 3 GeV/c part(x,y) vs centrality 50-60% 10-20% Warsaw University Faculty of Physics Seminar - malisa

  23. STAR Au+Au event Beyond leading particles STAR p+p event find this… …in this Warsaw University Faculty of Physics Seminar - malisa

  24. trigger Jets via azimuthal correlations STAR p+p event • trigger: highest pT track, pT>4 GeV/c • Df distribution for 2<pT<pTtrigger • normalize to number of triggers PRL 90, 082302 Warsaw University Faculty of Physics Seminar - malisa

  25. STAR Au+Au event Jets via azimuthal correlations Try the same in Au-Au (large combinatorics)… Warsaw University Faculty of Physics Seminar - malisa

  26. Azimuthal distributions in Au+Au pedestal and flow subtracted PRL 90, 082302 • Peripheral collisions: • very similar to p+p • Central collisions: • strong suppression • of away-side jet Warsaw University Faculty of Physics Seminar - malisa

  27. midcentral (20-60%) collisions nucl-ex/0407007 Further geometric detail Suppression depends on pathlength thru medium This analysis: cannot be initial state effect Warsaw University Faculty of Physics Seminar - malisa

  28. time Temperature ? Soft sector: ashes of the “QGP”… • Ultimately, jet quenching will only measure overall color field density • jets are probes of the system • jets are not “of the system” • medium (?) itself decays into low momentum particles (“soft sector”) • QGP is non-perturbative, low-Q phenomenon (need expt’l info) • dynamics - difficult but crucial here 99.5% • Is it a “big” “system/medium”? • bulk, collective behaviour • How does it evolve in spacetime? • dynamic response to pressure, EoS Warsaw University Faculty of Physics Seminar - malisa

  29. How do semi-central collisions evolve? 1) Superposition of independent p+p: momenta pointed at random relative to reaction plane Warsaw University Faculty of Physics Seminar - malisa

  30. How do semi-central collisions evolve? 1) Superposition of independent p+p: high density / pressure at center momenta pointed at random relative to reaction plane 2) Evolution as a bulksystem Pressure gradients (larger in-plane) push bulk “out”  “flow” “zero” pressure in surrounding vacuum more, faster particles seen in-plane Warsaw University Faculty of Physics Seminar - malisa

  31. mass systematic STAR, PRL90 032301 (2003) b ≈ 10 fm 4v2 b ≈ 6.5 fm b ≈ 4 fm symmetry, thermal smearing v2 --> bulk system N 2) Evolution as a bulksystem Pressure gradients (larger in-plane) push bulk “out”  “flow” v2(pT,m) consistent with anisotropic velocity field (i.e. property of bulk) more, faster particles seen in-plane Warsaw University Faculty of Physics Seminar - malisa

  32. Hydro: P. Huovinen, P. Kolb, U. Heinz Elliptic flow – collectivity & sensitivity to early system • “Elliptic flow” • Bulk collective motion • x anisotropyp anisotropy • sensitive to early pressure • evidence for • early thermalization • QGP in early stage (H. Sorge, PRL 78 2309; 82 2048.)   10 GeV/fm3 Hydrodynamic calculation of system evolution Warsaw University Faculty of Physics Seminar - malisa

  33. A more direct handle? • elliptic flow (v2)  evidence towards QGP at RHIC • oblique connection to crucial issue of dynamics/spacetime geometry • theoretical dynamical evolution: hope of “peering through the mist” Two particle intensity interferometry: a more direct handle on spacetime Warsaw University Faculty of Physics Seminar - malisa

  34. HBT: The Bottom line… if a pion is emitted, it is more likely to emit another pionwith very similar momentumif the source is small Creation probability r(x,p) = U*U F.T. of pion source Measurable! probingsource geometry through interferometry p1 r1 x1 p source r(x) 1 m x2 r2 p2 experimentally measuring this enhanced probability: quite challenging 5 fm Warsaw University Faculty of Physics Seminar - malisa

  35. Au+Au R ~ 6 fm p+p R ~ 1 fm d+Au R ~ 2 fm Correlation functions for different colliding systems STAR preliminary C2(Qinv) Qinv (GeV/c) Still amazing to me… Interferometry probes the smallest scales ever measured ! Warsaw University Faculty of Physics Seminar - malisa

  36. p1 Rlong q Rside p2 Rout beam direction More detailed geometry Relative momentum between pions is a vector  can extract 3D shape information Rlong – along beam direction Rout – along “line of sight” Rside –  “line of sight” Warsaw University Faculty of Physics Seminar - malisa

  37. Why do the radii fallwith increasing momentum ?? Warsaw University Faculty of Physics Seminar - malisa

  38. Decreasing R(pT) • usually attributed to collective flow • flow integral to our understanding of R.H.I.C.; taken for granted • femtoscopy the only way to confirm x-p correlations – impt check Kolb & Heinz, QGP3 nucl-th/0305084 Warsaw University Faculty of Physics Seminar - malisa

  39. Decreasing R(pT) • usually attributed to collective flow • flow integral to our understanding of R.H.I.C.; taken for granted • femtoscopy the only way to confirm x-p correlations – impt check • Non-flow possibilities • cooling, thermally (not collectively) expanding source • combo of x-t and t-p correlations early times: small, hot source late times: large, cool source Warsaw University Faculty of Physics Seminar - malisa

  40. Decreasing R(pT) • usually attributed to collective flow • flow integral to our understanding of R.H.I.C.; taken for granted • femtoscopy the only way to confirm x-p correlations – impt check • Non-flow possibilities • cooling, thermally (not collectively) expanding source • combo of x-t and t-p correlations 1500 fm/c (!) MAL et al, PRC49 2788 (1994) Warsaw University Faculty of Physics Seminar - malisa

  41. Decreasing R(pT) • usually attributed to collective flow • flow integral to our understanding of R.H.I.C.; taken for granted • femtoscopy the only way to confirm x-p correlations – impt check • Non-flow possibilities • cooling, thermally (not collectively) expanding source • combo of x-t and t-p correlations • hot core surrounded by cool shell • important ingredient of Buda-Lund hydro picturee.g. Csörgő & LörstadPRC54 1390 (1996) Warsaw University Faculty of Physics Seminar - malisa

  42. Each scenario generates x-p correlations • Decreasing R(pT) • usually attributed to collective flow • flow integral to our understanding of R.H.I.C.; taken for granted • femtoscopy the only way to confirm x-p correlations – impt check but… x2-p correlation: yes x-p correlation: yes • Non-flow possibilities • cooling, thermally (not collectively) expanding source • combo of x-t and t-p correlations • hot core surrounded by cool shell • important ingredient of Buda-Lund hydro picturee.g. Csörgő & LörstadPRC54 1390 (1996) x2-p correlation: yes x-p correlation: no t x2-p correlation: yes x-p correlation: no Warsaw University Faculty of Physics Seminar - malisa

  43. pT T • flow-dominated “models” can reproduce soft-sector x-space observables • imply short timescales • however, are we on the right track? [flow] • puzzles?  check your assumptions! • look for flow’s “special signature”x-p correlation • In flow pictures, low-pT particles emitted closer to source’s center (along “out”) • non-identical particle correlations(FSI at low v) probe: • (x1-x2)2 (as does HBT) • x1-x2  K p [click for more details on non-id correlations] F. Retiere & MAL, nucl-th/0312024 Csanád, Csörgő, Lörstad nucl-th/0311102 and nucl-th/0310040 Warsaw University Faculty of Physics Seminar - malisa

  44. T T x (fm) x (fm) A. Kisiel (STAR) QM04 • extracted shift in emission point x1-x2 consistent w/ flow-dominated blastwave • In flow pictures, low-pT particles emitted closer to source’s center (along “out”) • non-identical particle correlations(FSI at low v) probe: • (x1-x2)2 (as does HBT) • x1-x2 Warsaw University Faculty of Physics Seminar - malisa

  45. p1 p2 More information Relative momentum between pions is a vector  can extract 3D shape information Rlong – along beam direction Rout – along “line of sight” Rside –  “line of sight” Rout Rside Warsaw University Faculty of Physics Seminar - malisa

  46. small RSIDE RSIDE big RSIDE  0 /4 /2 3/4 -RP (rad) Source shape • “observe” the source from all angles relative to the reaction plane • expect oscillations in radii for non-round sources reaction plane Warsaw University Faculty of Physics Seminar - malisa

  47. central collisions • estimate INIT from Glauber • from asHBT: mid-central collisions STAR nucl-ex/0411036 peripheral collisions Shape evolution: suggests short timescale Look at it from another view… Measured final source shape STAR, PRL93 012301 (2004) Expected evolution: ? Warsaw University Faculty of Physics Seminar - malisa

  48. p1 q p2 Disintegration timescale Relative momentum between pions is a vector  can extract 3D shape information Rlong – along beam direction Rout – along “line of sight”  increases with emission timescale Rside –  “line of sight” Rout Rside Warsaw University Faculty of Physics Seminar - malisa

  49. Disintegration timescale - expectation 3D 1-fluid Hydrodynamics Rischke & Gyulassy, NPA 608, 479 (1996) with transition with transition “” “” • Long-standing favorite signature of QGP: • increase in , ROUT/RSIDE due to deconfinement  confinement transition • expected to “turn on” as QGP energy threshold is reached Warsaw University Faculty of Physics Seminar - malisa

  50. 8 8 6 6 RO (fm) 4 4 RS (fm) 1.5 1.25 RO / RS 1.0 increasing collision energy Disintegration timescale - observation • no threshold effect seen • RO/RS ~ 1 RHIC Warsaw University Faculty of Physics Seminar - malisa

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