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

Helen Caines DNP Hawaii – Sept 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)

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept  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.

Helen Caines DNP Hawaii – Sept 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, (R) (2004)

Helen Caines DNP Hawaii – Sept 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/ M.Lisa et al. Scaling works across a large energy range

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept 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%

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept 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/ SCF only produced in nucleus-nucleus collisions R AA ≠ R CP

Helen Caines DNP Hawaii – Sept 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?

Helen Caines DNP Hawaii – Sept ● 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

Helen Caines DNP Hawaii – Sept 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.”

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

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept Strangelet trigger

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

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept 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)

Helen Caines DNP Hawaii – Sept 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?

Helen Caines DNP Hawaii – Sept 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!

Helen Caines DNP Hawaii – Sept But then at √s= 8.8 GeV  C to GC predicts a factor 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)

Helen Caines DNP Hawaii – Sept On linear scales

Helen Caines DNP Hawaii – Sept 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!

Helen Caines DNP Hawaii – Sept Lots of evidence

Helen Caines DNP Hawaii – Sept No evidence

Helen Caines DNP Hawaii – Sept 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)

Helen Caines DNP Hawaii – Sept 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!

Helen Caines DNP Hawaii – Sept But then at √s= 8.8 GeV  C to GC predicts a factor 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)

Helen Caines DNP Hawaii – Sept 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

Helen Caines DNP Hawaii – Sept 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.

Helen Caines DNP Hawaii – Sept 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 to per central Au+Au collisions are set for mass  30 GeV/c 2

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