Recent RHIC Results on Bulk Properties Richard Hollis
Recent RHIC Results on Bulk Properties Richard Hollis 21 st June 2007 RHIC & AGS Users’ Meeting
The Road Ahead ¢ Bulk properties measurements at RHIC l New measurements and expanded systematics ¢ Scaling with Npart, Nch or epart ¢ Simple Scaling Rules 2 Richard Hollis University of Illinois at Chicago 21 st June 2007
Systematic Studies ¢ ¢ l RHIC input l l Varied Cross-section Energy Collision system (species) l ¢ Study dominating effect l ¢ ¢ Experimental input l l l Rapidity Species System size/configuration ¢ ¢ esp. hard collisions Influence toward bulk properties Npart or fractional cross-section Probe range of x. F Relative enhancement of baryons to mesons Path length and collective effects Do systematic studies paint a consistent picture of bulk particle production? 3 Richard Hollis University of Illinois at Chicago 21 st June 2007
Total Charged Hadron Distributions d. N/dh flow{v 2, v 1, s(v 2)/v 2} 21 st June 2007 RHIC & AGS Users’ Meeting
Multiplicity QM 2006 ¢ Latest Results l l ¢ Mid-rapidity l ¢ Au+Au (Peripheral) Cu+Cu (22. 4 Ge. V) Factorization in energy and centrality 4 p l Extended longitudinal scaling – factorizes in energy and centrality Factorization persistent across all systems 5 Richard Hollis University of Illinois at Chicago 21 st June 2007
Elliptic Flow QM 2006 ¢ Similar systematic dependencies as multiplicity ¢ Mid-rapidity: l ¢ v 2/epart scaling holds over a broad range of collision energy and system sizes h dependence l l Matched Npart v 2/epart holds over large h range Extended longitudinal scaling Geometrical scaling with epart 6 Richard Hollis University of Illinois at Chicago 21 st June 2007
Directed Flow ¢ v 1 is found to scale with collision energy, not collision species l ¢ Comparison of same overlap geometry Relative shift in ybeam Extended longitudinal scaling applies 7 Richard Hollis University of Illinois at Chicago 21 st June 2007
Elliptic Flow Fluctuations ar. Xiv: nucl-ex/0702036 ¢ ¢ Large fluctuations in the v 2 signal Au+Au @ 200 Ge. V Geometrical Properties are imprinted on the data: l 8 Eccentricity via Flow Richard Hollis University of Illinois at Chicago 21 st June 2007
Final Charged Particle Distribution Summary ¢ Final distributions provide a consistent picture of particle production driven by simple scaling laws: Energy, centrality factorization l Detailed initial geometrical configuration (epart) l ¢ How do differential measurements compare 9 Richard Hollis University of Illinois at Chicago 21 st June 2007
p. T Distributions Yield versus p. T v 2{p. T} Freeze-out properties 21 st June 2007 RHIC & AGS Users’ Meeting
Yield versus p. T QM 2006 ¢ Mid-rapidity yields versus p. T l ¢ Factorization in energy and centrality Similar behavior to bulk yields 11 Richard Hollis University of Illinois at Chicago 21 st June 2007
Elliptic flow at mid-rapidity PRL 98, 162301 (2007) ¢ Latest Results: l ¢ v 2{p. T} (200 Ge. V) v 2{p. T} shape independent of centrality and system size v 2{p. T}: universal scaling? 12 Richard Hollis University of Illinois at Chicago 21 st June 2007
Kinetic freeze-out properties QM 2006 ¢ Latest Results: l Freeze-out properties ¢ Freeze-out temperature and flow velocity follow a common dependence with number of charged particles at mid-rapidity ¢ Mean-p. T follow same trend STAR Preliminary Similar dependence noted by PHENIX (JPS 2007) Scaling of low-p. T properties with Nch 13 Richard Hollis University of Illinois at Chicago 21 st June 2007
Chemical freeze-out properties QM 2006 ¢ Latest Results: l ¢ Cu+Cu at 200 and 62. 4 Ge. V Universal chemical freeze-out temperature, Tch, is observed for all studied systems STAR Preliminary 14 Richard Hollis University of Illinois at Chicago 21 st June 2007
p. T Distributions Summary ¢ First differential measurements: “Universal scaling” of elliptic flow versus p. T l Nch scaling of kinetic freeze-out properties l 15 Richard Hollis University of Illinois at Chicago 21 st June 2007
Chemical properties Strangeness production Baryon enhancement v 2{KE/nq, y} 21 st June 2007 RHIC & AGS Users’ Meeting
Strangeness production – K± Latest Results: l Forward ¢ 62. 4 Ge. V Au+Au ¢ Charge “splitting” of K/p as observed at SPS ¢ “Chemical equivalence” with SPS energies 17 Richard Hollis University of Illinois at Chicago Mid-rapidity QM 2006 21 st June 2007
Strangeness production – L QM 2006 ¢ ¢ Latest Results: l L scale reasonably with Npart for the same energy STAR Preliminary Enhanced strangeness production due to core of core/corona model l More core per Npart in Cu+Cu collisions Phys. Rev. Lett. 98, 152301 (2007) 18 Richard Hollis University of Illinois at Chicago 21 st June 2007
Recombination Model nucl-th/0602024 ¢ Recombination Model l Describes the p. T dependence of strange particles L(STAR) K 0 S(STAR) • K, L ¢ Fits provide good agreement with data ¢ Qualitatively reproduces L/K 0 S ratio 19 Richard Hollis University of Illinois at Chicago 21 st June 2007
Baryon Enhancement QM 2006 ¢ Enhancement is maximal in the intermediate-p. T region l Cu+Cu @ 200 Ge. V STAR Preliminary Cu+Cu data exhibit the same systematic trends as for Au+Au system Illustrative p+p (not a fit) 20 Richard Hollis University of Illinois at Chicago 21 st June 2007
Baryon Enhancement JPS 2007 ¢ Npart scaling for p/p l ¢ Integrated intermediatep. T region Moreover, ET scaling exists between 200 and 62. 4 Ge. V (pbar/p–) l Baryon transport contributes at 62. 4 Ge. V for protons PHENIX preliminary Scaling of intermediate-p. T properties with ET 21 Richard Hollis University of Illinois at Chicago 21 st June 2007
Recombination Revisited QM 2006 ¢ Recombination predicts other B/M ratios l ¢ Qualitative agreement. s-quark dependence on peak position is predicted l 22 But at higher-p. T than data suggests Richard Hollis University of Illinois at Chicago 21 st June 2007
Recombination Revisited WWND QM 2006 2007 ¢ Validity test: l ¢ W, f A good description of the multistrange spectra l l W: dominated by thermal term Look at W correlations • No near-side correlation expected ¢ Correlation observed l 23 Magnitude of near-side correlation is independent of strange-quark content Richard Hollis University of Illinois at Chicago 21 st June 2007
Quark scaling of elliptic flow PRL 98, WWND 2007 162301 (2007) ¢ Latest Results: l ¢ v 2/nq scales with KET/nq Holds for Cu+Cu data l 24 Once e is accounted for Richard Hollis University of Illinois at Chicago 21 st June 2007
Identified v 2 ¢ For different centrality bins: l No universal scaling ←Centrality Dependence Min-bias, particle id’d→ 25 Richard Hollis University of Illinois at Chicago 21 st June 2007
Elliptic flow versus rapidity Xi’an 06 ¢ Identified flow versus p. T and rapidity l No appreciable difference in shape h≈0 h≈3 BRAHMS Preliminary • cf. PHENIX flow at midrapidity l No difference in magnitude Systematics fit into existing data 26 Richard Hollis University of Illinois at Chicago 21 st June 2007
Chemical Summary ¢ Further differential measurements: l pbar/p – Npart scaling l Qualitative description of B/M ratios in the recombination picture • But fails to describe the multi-strange correlations l Universal scaling of identified v 2{p. T} • Observed for min-bias across system size • Not observed versus centrality 27 Richard Hollis University of Illinois at Chicago 21 st June 2007
Summary ¢ Bulk properties measurements at RHIC l New measurements and expanded systematics ¢ Scaling with Npart, Nch or epart l For the bulk to intermediate-p. T regions ¢ Simple Scaling Rules l Applicable over a broad range of centrality, energy and colliding species 28 Richard Hollis University of Illinois at Chicago 21 st June 2007
Thanks! ¢ Credits: l BRAHMS • Flemming Videbaek l PHENIX • Barbara Jacak, Craig Ogilvie l STAR • Aihong Tang, Subhasis Chattopadhyay , Olga Barannikova, Rene Bellwied l PHOBOS • Wit Busza, David Hofman, Aneta Iordanova Evan, 6 weeks and 2 days 29 Richard Hollis University of Illinois at Chicago 21 st June 2007
Back-up Slides 21 st June 2007 RHIC & AGS Users’ Meeting
¢ Core/corona l Core – high density region ¢ Phys. Rev. Lett. 98, 152301 (2007) l My own simulations l Based on similar ideas Thesis (2005) Corona – low density region around the edge Cu+Cu “core” Au+Au “corona” Cu+Cu “corona” 31 Richard Hollis University of Illinois at Chicago 21 st June 2007
Particle Ratios versus system size QM 2006 ¢ Particle Ratios l l ¢ 200 and 62. 4 Ge. V Au+Au and Cu+Cu Near mid-rapidity Weak centrality dependence, no system size dependence of particle ratios 32 Richard Hollis University of Illinois at Chicago 21 st June 2007
33 Richard Hollis University of Illinois at Chicago 21 st June 2007
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