1. Helen Caines Yale University DNP Hawaii– Sept. 2005 Recent Strangeness and Exotics results from RHIC “Little strokes fell great oaks.” Old English Proverb

2. Helen Caines DNP Hawaii – Sept. 2005 2 200 GeV Au+Au sss  sss  200 GeV Au+Au s  uds  200 GeV Au+Au ss  dss  200 GeV Au+Au  200 GeV p+p  200 GeV p+p  200 GeV d+Au  200 GeV d+Au  200 GeV d+Au  62 GeV Au+Au  62 GeV Au+Au  62 GeV Au+Au  *  (uus) More Au+Au and Cu+Cu soon to come ! Some of the data  *(1520) (uds)

3. Helen Caines DNP Hawaii – Sept. 2005 3 N part < 20 or low energies  ratios rising Baryon density Mid-rapidity BRAHMS PRELIMINARY  b drives the production ratios Differences appearing in p-p production

4. Helen Caines DNP Hawaii – Sept. 2005 4 s-Baryon production is ~constant at mid-rapidity. STAR Preliminary  s-Baryon rises smoothly at mid-rapidity. Au+AuPb+Pb Collision energy dependencies What determines the overall yields? STAR Preliminary

5. Helen Caines DNP Hawaii – Sept. 2005 5  and  yields in AuAu relative to pp rises. Centrality dependence Production volume not well modelled by N part Canonical suppression increases with increasing strangeness Redlich et al.

6. Helen Caines DNP Hawaii – Sept. 2005 6 Motivation from h - N.B.: SPS energy only 17 GeV There’s a correlation between dN ch /d  and N part /2 If know n pp can predict yield at any  N part  small dotted lines are: dN ch /d  n pp (1-x)N part /2 + xN bin n pp = Yield in pp = 2.29 ( 1.27) x = 0.13 PHOBOS: Phys. Rev. C70, 021902(R) (2004)

7. Helen Caines DNP Hawaii – Sept. 2005 7 HBT and dN ch /d  HBT radii ~linear as a function N part 1/3 Even better in (dN ch /d  ) 1/3 power 1/3 gives approx. linear scale nucl-ex/0505014 M.Lisa et al. Scaling works across a large energy range

8. Helen Caines DNP Hawaii – Sept. 2005 8 Strangeness and dN ch /d  SPS and RHIC data follows same curves as a func. of dN ch /d η dN ch /d η - strongly correlated to the entropy of the system! Look at yields relative to pp Entropy alone seems to drive much of the soft physics

9. Helen Caines DNP Hawaii – Sept. 2005 9 Flavor dependence of scalings Binary scaling for heavy flavor quark hadrons PHENIX D’s Participant scaling for light quark hadrons Hadrons with strange quarks are add-mixture of N part and N bin

10. Helen Caines DNP Hawaii – Sept. 2005 10 p,K, p 200 GeV > 62 GeV T kin 200 GeV = 62 GeV  200 GeV = 62 GeV T kin 200 GeV > 62 GeV Spectral distributions T kinetic from a Blast-Wave is not same as the Temperature from a Hydro Model. Temperature T kinetic is higher for baryons with higher strange quark content for Blast-wave fits. Spectral shapes are different. Most Central Collisions 0.13 T=100 MeV T=132 MeV

11. Helen Caines DNP Hawaii – Sept. 2005 11 Nuclear modification factors 0-5% 40-60% √s NN =200 GeV 62 GeV R cp shows less suppression. √s NN =62 GeV 0-5% 40-60% Baryon and meson suppression sets in at different p T. Baryon and meson suppression sets in at same quark p T. Coalesence/recombination 0-5% 40-60%

12. Helen Caines DNP Hawaii – Sept. 2005 12 No apparent flavor dependence of energy loss Flavor independence of Modification factor? h - - u and d dominated e - c (maybe b) dominated  – s quark dominated

13. Helen Caines DNP Hawaii – Sept. 2005 13 R AA of strange particles Particles with strange quarks scale differently to non-strange Ordering with strangeness content! s-quark K ±, K 0 s,  and h - all scale similarly Phase space effects dominate out to high p T

14. Helen Caines DNP Hawaii – Sept. 2005 14 Model explanation HIJING/BBar + K T ~ 1 GeV Strong Colour Field qualitatively describes R AA. SCF – long range coherent fields SCF behaviour mimicked by doubling the effective string tension SCF controls  qq and qqqq production rates and  s Topor Pop et al. hep-ph/0505210 SCF only produced in nucleus-nucleus collisions R AA ≠ R CP

15. Helen Caines DNP Hawaii – Sept. 2005 15 m T scaling STAR Preliminary p+p 200 GeV No complete m T scaling Au-Au Radial flow prevents scaling at low m T Seems to scale at higher m T p-p Appears to be scaling at low m T Baryon/meson splitting at higher m T – Gluon jets?

16. Helen Caines DNP Hawaii – Sept. 2005 16 ● Λ ● Anti-Λ ● K S 0 ● 50% p/pbar ■ Λ □ Λbar ● 95% п ■ K 0 s N ch /N Trigger p T Trigger Au+Au 0-5% 1.0<p T Associated <2.0 Hint of split between baryons and mesons in near side yield at high p T Need more stats Strange PID correlations

17. Helen Caines DNP Hawaii – Sept. 2005 17 Exotics – Pentaquarks  +  K + n D.S. Carman, Ohio University JLab Users meeting 1.“The published results on the  + from analysis of the g2a data cannot be reproduced in the analysis of the high statistics g10 data.” 2.The statistical significance in the published data is a coupling of a statistical fluctuation and the underestimate of the background in the mass region of 1.54 GeV.” Clas Statement 6/30/04: “Improved analysis of this data finds that the significance of the observed peak may not be as large as indicated. We expect a definitive answer from a much larger statistics data set that is currently being analyzed.”

18. Helen Caines DNP Hawaii – Sept. 2005 18  ++ and  (1520)  (1520) Same analysis used for both plots STAR Preliminary d-Au

19. Helen Caines DNP Hawaii – Sept. 2005 19 If pK + peak at 1530 MeV/c 2 is real I = 1 Must be  +. Recent JLab null result! Yield from STAR analysis is very small Sensitivity of other experiments? No signal in 200 GeV p+p (8M) and Au+Au (~10M). What do these null observations mean? Production dynamics or unknown data set bias? Peak a fake? Analysis continues

20. Helen Caines DNP Hawaii – Sept. 2005 20 Strangelet search in STAR Use the forward ZDC + SMD Acceptance depends on charge Neutron Cluster Strangelet Cluster SMD Cluster shapes different Strangelets have high m/z ratio

21. Helen Caines DNP Hawaii – Sept. 2005 21 Strangelet trigger

22. Helen Caines DNP Hawaii – Sept. 2005 22 The results so far.. STAR Preliminary None found. Upper limits at level of a few 10 -6 to 10 -7 per central Au+Au collisions are set for mass  30 GeV/c 2

23. Helen Caines DNP Hawaii – Sept. 2005 23 Summary  Have gathered data for a very detailed study.  Evidence that strangeness production driven by the entropy of the system created, not only by N part.  Evidence of phase space suppression out to high p T.  Starting exporation of strangeness role in fragmentation  Little or no evidence for exotica The old “QGP” oak is starting to tremble and we’re probing its core

24. Helen Caines DNP Hawaii – Sept. 2005 24 How does volume affect production? When reach grand canonical limit strangeness will saturate. –Canonical (small system i.e. p-p): Quantum Numbers conserved exactly. Computations take into account energy to create companion to ensure conservation of strangeness. Relative yields given by ratios of phase space volumes P n /P n’ =  n (E)/  n’ (E) –Grand Canonical limit (large system i.e. central AA): Quantum Numbers conserved on average via chemical potential Just account for creation of particle itself. The rest of the system “picks up the slack”. Not new idea pointed out by Hagedorn in 1960’s (and much discussed since)

25. Helen Caines DNP Hawaii – Sept. 2005 25 p-p model calculations NLO - Nice agreement with K 0 s,  problematic Werner Vogelsang Calculations also work for  but not protons Recent EPOS calculations seem to be working Agreement due to a very strong soft component from string fragmentation in the parton ladder formalism. Can EPOS reproduce multiplicity dependence?

26. Helen Caines DNP Hawaii – Sept. 2005 26 Predictions at higher energies ♦ Canonical suppression increases with decreasing energy ♦ Canonical suppression increases with increasing strangeness σ(N part ) / N part = ε σ(pp) ε > 1 Enhancement!

27. Helen Caines DNP Hawaii – Sept. 2005 27 But then at √s= 8.8 GeV  C to GC predicts a factor 4 - 5 larger  - enhancement at √s NN = 8.8 GeV than at 17 GeV Perhaps yields don’t have time to reach limit – hadronic system? NA57 (D. Elia QM2004)

28. Helen Caines DNP Hawaii – Sept. 2005 28 On linear scales

29. Helen Caines DNP Hawaii – Sept. 2005 29 s-quark Ordering with strangeness content! Mesons (h + + h -, K 0 s,  ) follow similar trends. Strange baryons don’t show suppression. Rcp  Raa for strange baryons. Canonical suppression in p+p …? s-quarks scaled with N Bin u&d-quarks scaled with N part  scaled with N Part STAR Preliminary Au+Au p+p 0-5% √s NN =200 GeV s-quarks scaled with N Bin u&d-quarks scaled with N part  scaled with N Bin STAR Preliminary Au+Au p+p 0-5% √s NN =200 GeV R AA of Strange Particles STAR Preliminary Au+Au p+p 0-5% √s NN =200 GeV STAR Preliminary Particles with strange quarks scale differently than non-strange!

30. Helen Caines DNP Hawaii – Sept. 2005 30 Lots of evidence

31. Helen Caines DNP Hawaii – Sept. 2005 31 No evidence

32. Helen Caines DNP Hawaii – Sept. 2005 32 How does volume affect production? When reach grand canonical limit strangeness will saturate. –Canonical (small system i.e. p-p): Quantum Numbers conserved exactly. Computations take into account energy to create companion to ensure conservation of strangeness. Relative yields given by ratios of phase space volumes P n /P n’ =  n (E)/  n’ (E) –Grand Canonical limit (large system i.e. central AA): Quantum Numbers conserved on average via chemical potential Just account for creation of particle itself. The rest of the system “picks up the slack”. Not new idea pointed out by Hagedorn in 1960’s (and much discussed since)

33. Helen Caines DNP Hawaii – Sept. 2005 33 Predictions at higher energies ♦ Canonical suppression increases with decreasing energy ♦ Canonical suppression increases with increasing strangeness σ(N part ) / N part = ε σ(pp) ε > 1 Enhancement!

34. Helen Caines DNP Hawaii – Sept. 2005 34 But then at √s= 8.8 GeV  C to GC predicts a factor 4 - 5 larger  - enhancement at √s NN = 8.8 GeV than at 17 GeV Perhaps yields don’t have time to reach limit – hadronic system? NA57 (D. Elia QM2004)

35. Helen Caines DNP Hawaii – Sept. 2005 35 Backgrounds considered and rejected  0    e + e - e + e - Same-sign e’s within the K and p bands mostly in the low mass region opening angle cut  very effective removal Associated production  K +  p     Neither source produces a narrow peak !  ++   +p and using  as K doesn’t produce peak in relevant mass range Peak seems stable to variations in mtm cuts of daughters But still looking at other sources of background

36. Helen Caines DNP Hawaii – Sept. 2005 36 Exotica – Strangelets True ground state of baryonic matter - stable/meta-stable. Low z/A, reduced Coulomb, no fission - No limit on size. Can grow by absorbing neutrons - new energy source. Strangelet with A>10 17 (R>5 angstrom) will not be supported by the surface of the earth. Strangelets with M>2M SUN Will collapse into a black hole, Strangelets with M<2M SUN Will be similar to neutron stars.

37. Helen Caines DNP Hawaii – Sept. 2005 37 Upper Limit Z=-5 Z=+5 E886 (AGS) Adam Rusek E878 (AGS) Mike Bennett E864 (AGS) K.Barish, M.Munhoz, S.Coe, JN E864 (AGS) Z.Xu, G.V.Buren, R. Hoverstein NA52(CERN) R. Klingenberg, K.Pretzel - - - STAR (RHIC) Upper limits at level of a few 10 -6 to 10 -7 per central Au+Au collisions are set for mass  30 GeV/c 2

38. Helen Caines DNP Hawaii – Sept. 2005 38 Multiplicity dependence HIJING can only match data with extreme parameters: k T = 4 GeV EPOS results eagerly awaited.