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Strange Particles from NE X US 3

Fuming Liu Sergej Ostapchenko Tanguy Pierog Klaus Werner. hep-ph/0007198 Physics Reports 350 (2001) 93-289 hep-ph/0102194 Phys. Rev. Lett. 86 (2001) 3506. Hajo Drescher Michael Hladik. Joerg Aichelin Marcus Bleicher. SUBATECH , Nantes. Strange Particles from NE X US 3.

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Strange Particles from NE X US 3

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  1. Fuming Liu Sergej Ostapchenko Tanguy Pierog Klaus Werner hep-ph/0007198 Physics Reports 350 (2001) 93-289 hep-ph/0102194 Phys. Rev. Lett. 86 (2001) 3506 Hajo Drescher Michael Hladik Joerg Aichelin Marcus Bleicher SUBATECH, Nantes Strange Particles from NEXUS 3 (Basic ideas, baryon production in pp) NEXUS 3 : Consistent treatment of multiple scattering

  2. Problems with the String Model Approach Particle production in pp scattering via string fragmentation Strings decay into chains of hadrons pp ==> 2 strings Not enough multiplicity fluctuations ==>

  3. Two Pairs of strings In general: n pairs of strings

  4. 2 / 2 Probability of n pairs ? Gribov Regge : Pomeron (= pair of strings) ...

  5. String model -- Gribov-Regge String model: first and subsequent pairs are of different nature Gribov-Regge: all Pomerons are identical String model: energy-momentum is properly shared among strings Gribov-Regge: energy-sharing is not considered inconsistent

  6. And …traditional string models fail badlywhen it comes to strange baryon production in pp ...

  7. The new approach Aim: connecting properly string model and Gribov-Regge Theory … and the parton model Extending work by Gribov, Kaidalov, Capella ...

  8. Basic Features Result of a pp collisions: 2 remnants and n Pomerons (all identical) Pomeron = 2 strings Energy-momentum properly shared Same formalism for particle production and probability calculations

  9. Notations Consider parton-parton scattering

  10. Amplitude: Squared amplitude => interference terms: Inelastic scattering in pp: remnant => Symbolic notation

  11. (Elastic and inelastic elem. Interactions) Inelastic scattering in AB: Squaring amplitude  sum over many interference terms expressed via cut and uncut elementary diagrams full energy conservation!! remnant Pomerons: multiplicity proportional to number of binary collisions Remnants: multiplicity proportional to participants

  12. Pomeron-Pomeron Interactions  • Diffraction • Screening • Shadowing • Saturation • Increasing mult. fluctuations • Solving F2-tot puzzle

  13. Hadronization Multiple scattering theory determines how many Pomerons are involved in each nucleon-nucleon interaction and the momenta of each Pomeron. Then: Pomeron  strings Strings  hadrons

  14. From Pomerons to Strings In the multiple scattering theory a dashed line represents a cut Pomeron The complicated hadronic structure is “hidden” What is the precise structure of a cut Pomeron? Pomeron = 2 strings

  15. pp scattering: 1 Pomeron 2 Pomerons etc Projectile remnant q, q-bar or qq qq-bar (sea quarks) strings Target remnant Crucial: separation of Pomerons and remnants otherwise completely wrong baryon yields (FM Liu, M Bleicher, J Aichelin, T. Pierog, KW et al)

  16. Baryon ratios in pp at 158 GeV 3 Traditional string models NEXUS: < 1

  17. Antibaryon/baryon ratios at RHIC (pp -1<y<1):NEXUS:data (A.Billmeier,STAR):proton: 0.81 (0.81 +- )Lambda: 0.895 (0.89 +- 0.03)Xi: 0.95 (0.97 +- 0.04) Omega: 0.94(0.90 +- 0.19)

  18. Why does the conventional string model give more antiomegas than omegas? A string end flavor u or d prevents the production of omegas NEXUS : projectile/target flavor is in the remnants not in the strings

  19. Baryon spectra in pp at 158 GeV Leading particles (mainly from remnants) Theory: NEXUS (FM Liu et al) Data: NA49

  20. Summary Consistent multiple scattering formalism => separation remnants - Pomerons (strings) => antibaryon/baryon ratios R < 1 contrary to conventional string models strings: R = 1 remnants: R < 1

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