S. PrattNSCL/MSU Deciphering the Space-Time Evolution of Heavy-Ion Collisons with Correlation Measurements Scott Pratt Michigan State University

S. PrattNSCL/MSU Hanbury-Brown Twiss: Theory Assume source factorizes, =cos(qr) for Bosons Probability of two particles of momentum p being separated by r _ Six dimensions of C(p,q) yield six dimensions of F(p,r) __ Fourier transform …

S. PrattNSCL/MSU HBT: Theory _ Inverting C(p,q)  F(p,r) Measures probability cloud Overall source can be larger Inversion depends on |  (q,r)| 2 _

S. PrattNSCL/MSU Measuring Lifetime

S. PrattNSCL/MSU Role of Dynamics: Experimental Signatures Dramatic change in nn E/A ~ 40 MeV see also, IMF correlations, Bauge et al, PRL70 (93)

S. PrattNSCL/MSU RQMD + CRAB vs. AGS DATA Microscopic models do surprisingly well at AGS and SPS

S. PrattNSCL/MSU RHIC RESULTS Thermal Model: T = 105 MeV, v max = 0.7 R max = 13 fm,  = 10 fm/c HBT RADII Would have to accelerate to full speed instantaneously! STAR Collab., PRL (2001)

S. PrattNSCL/MSU  Hydro/Cascade can not fit HBT S. Bass and A.Dumitru, nucl-th/ D.Teaney, PhD thesis. P. Kolb, PLB (2001) Volume too large by factor of ~ 3! D.Teaney, PhD thesis HYDRO         RHIC RESULTS

S. PrattNSCL/MSU THE HBT PUZZLE AT RHIC A.Incorrect Analysis or Interpretation of Results Experimental error: 2-track resolution, Coulomb correction HBT Dogma is wrong: 3 rd -Body Int., Multi-  symm., Bjorken geometry B. Take Data at Face Value EXTREME ACCELERATION, dP/d  >  /3 ?? Early disassociation Breakup at high phase space density (   ~100 MeV) Mass Drops? K.Haglin and S.P., PRC59, 3304 (99) Thermal Models are misapplied Entropy is low by ~ 1.0 per particle Coherent Stopping? Colored Glass? Gluon Condensate?

S. PrattNSCL/MSU Balance Functions, a Signal of Late-Stage Hadronization S. Bass, P. Danielewicz and S.P. PRL85, 2689 (2000) 5-10 fm/c Most qq pairs created at hadronization Y +  Y  ~ (T/m) 1/2 ~ 0.5 _ 1 fm/c Flux tube and high velocity gradient separate charges Y +  Y  ~ 1 Hadronic Scenario QGP Scenario

S. PrattNSCL/MSU If one knows breakup T, one can determine   Difficulty: Identifying balancing partners

S. PrattNSCL/MSU Balance Functions: How They Work For each charge +Q, there is one extra balancing charge –Q. Charges: electric, strangeness, baryon number

S. PrattNSCL/MSU Assume Q &Q produced at same point.  y  determined only by T and m. Proton balance function narrower that pion’s. Thermal model always narrower than string model. Thermal Model

S. PrattNSCL/MSU Hadronic Model  Balance functions ~10% BROADER for AA than for pp due to diffusion. Proton-antiproton balance functions become broader due to annihilation. Delayed Hadronization Width determined by Breakup T.  Balance functions ~ 20% NARROWER for Central AA than for pp. Balance Functions: Quantitative Expectations RQMD, provided by Q.H.Zhang.

S. PrattNSCL/MSU Preliminary STAR Results Identified Pions More Central Collisions  Narrower Balance Functions !!! M. Tonjes, ParkCity, 2001

S. PrattNSCL/MSU STAR Summary QUANTITATIVELY consistent with HIJING  Thermal Production in Late Stage

S. PrattNSCL/MSU Balance Functions: To-Do List 1.Look at pp collisions. 2.Analyze K + K - and pp balance functions. 3.Measure p t dependence. 4.Analyze as functions of ,  p t, Q inv. 5.Role of transverse collective flow, resonances. 6.Quantitatively understand normalization: Experimental acceptance Interplay between acceptance and spectra. Loss of partners to other channels, e.g.,  + balancing partner could be K . All could be accomplished in next 12 months.