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Hadronization – When and How

Hadronization – When and How. Scott Pratt, Michigan State University. What are Balance Functions ? What do STAR results say? Qualifications for large baryon number environment. Gluonic modes carry entropy, but no charge

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Hadronization – When and How

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  1. Hadronization – When and How Scott Pratt, Michigan State University • What are Balance Functions? • What do STAR results say? • Qualifications for large baryon number environment S. Pratt NSCL/MSU

  2. Gluonic modes carry entropy, but no charge Coalescence of quarks at sameT should have:Nmesons ~ Nquarks + Nantiquarks quark number ~ doubles Coherent sources (chiral fields, bag energy…) can produce new charge. Charge is Created at Hadronization • For B=0 QGP, >1/2 of charge is created at hadronization • For CBM, ???? S. Pratt NSCL/MSU

  3. 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

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

  5. Balance Function: Definition S. Pratt NSCL/MSU

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

  7. Bjorken Thermal Blast Wave Model • Assume Q &Q produced at same point.•BDy determined only by T, v and m. • Proton balance functionnarrower that pion’s. • Thermal model always narrower than string model. • Transverse flow narrows B(Dy) S. Pratt NSCL/MSU

  8. What if Balance functions are narrower for AA than they are for pp? RQMD-type descriptions are qualitatively wrong AND EITHER • 1. Delayed production of charge • Change in degrees of freedom • QGP least exotic explanation • OR • 2. Anomalously short mean free paths • would be contrary to common wisdom S. Pratt NSCL/MSU

  9. What if AA balance functionsare NOT narrower? RQMD, provided by Q.H.Zhang. • Gluonic modes did not contribute to entropy • No dramatic change in degrees of freedom. • Usual strangeness enhancement arguments are wrong. • J/Y & Jet-quenching phenomenology are misguided. S. Pratt NSCL/MSU

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

  11. The HBT Hole S.Jeon and S.P., hep-th (2001) No HBT +HBT +Coulomb • HBT Weight: • Use parameters to getweight: T=190 MeV, l=.7, Rinv=7 fm • Dip at small Dy • Applied to non-partners • Proportional to dn/dy • Does not change norm. • No significant changein y • Dip similar to that seenby STAR S. Pratt NSCL/MSU

  12. STAR Summary S. Pratt NSCL/MSU

  13. STAR, width vs. centrality All Charges Identified Pions Blast Wave (extreme) As b 0, data are consistent with ~100% delayedproduction with T ~ 110 MeV, v ~ 0.75 S. Pratt NSCL/MSU

  14. Can We Convict the QGP? • Analyze pp collisions. • Analyze K+K- and p-pbar balance functions. • Decipher pt dependence. • Study as functions of Qbeam, Qout, Qside, Qinv. • Quantitatively understand normalization.(Loss of partners to other channels, e.g., p+ balancing partner could be K-.) • Much can be accomplished with STAR’s 200 GeV data • PHENIX may be able to measure p-pbar balance function S. Pratt NSCL/MSU

  15. Detector Requirements? • Large coverage, Dy >1.5 • Good Particle ID over large range. • Equal Acceptance for + and -, e.g. STAR • Millions of Events S. Pratt NSCL/MSU

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