Deciphering the Space-Time Evolution of Heavy-Ion Collisons with Correlation Measurements

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

2. Hanbury-Brown Twiss: Theory Assume source factorizes, Fourier transform … =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) S. Pratt NSCL/MSU

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

4. Measuring Lifetime S. Pratt NSCL/MSU

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

6. RQMD + CRABvs. AGS DATA Microscopic models do surprisingly well at AGS and SPS S. Pratt NSCL/MSU

7. HBT RADII RHIC RESULTS Thermal Model: T = 105 MeV, vmax = 0.7 Rmax = 13 fm, t = 10 fm/c Would have to accelerate tofull speed instantaneously! STAR Collab., PRL (2001) S. Pratt NSCL/MSU

8. RHIC RESULTS  • Hydro/Cascade can not fit HBT S. Bass and A.Dumitru, nucl-th/0012085 D.Teaney, PhD thesis. P. Kolb, PLB (2001) D.Teaney, PhD thesis HYDRO         Volume too large by factor of ~ 3! S. Pratt NSCL/MSU

9. THE HBT PUZZLE AT RHIC • Incorrect Analysis or Interpretation of Results • Experimental error: 2-track resolution, Coulomb correction • HBT Dogma is wrong: 3rd-Body Int., Multi-p symm., Bjorken geometry • B. Take Data at Face Value • EXTREME ACCELERATION, dP/de > 1/3 ?? • Early disassociation • Breakup at high phase space density (mp~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. Pratt NSCL/MSU

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

11. If one knows breakup T,one can determine s dh Difficulty: Identifying balancing partners S. Pratt NSCL/MSU

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

13. Thermal Model • Assume Q &Q produced at same point.•Dy determined only by T and m. • Proton balance functionnarrower that pion’s. • Thermal model always narrower than string model. S. Pratt NSCL/MSU

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

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

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

17. Balance Functions: To-Do List • Look at pp collisions. • Analyze K+K- and pp balance functions. • Measure pt dependence. • Analyze as functions of Df, Dpt, Qinv. • Role of transverse collective flow, resonances. • Quantitatively understand normalization: • Experimental acceptance • Interplay between acceptance and spectra. • Loss of partners to other channels, e.g., p+ balancing partner could be K-. All could be accomplished in next 12 months. S. Pratt NSCL/MSU