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

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

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Two Pairs of strings In general: n pairs of strings

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

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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

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And … traditional string models fail badly when it comes to strange baryon production in pp...

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

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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

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Notations Consider parton-parton scattering

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

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

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Pomeron-Pomeron Interactions Shadowing Saturation Diffraction Screening Increasing mult. fluctuations Solving F 2 - tot puzzle

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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

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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

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1 Pomeron2 Pomerons etc Projectile remnant Target remnant strings Crucial: separation of Pomerons and remnants otherwise completely wrong baryon yields (FM Liu, M Bleicher, J Aichelin, T. Pierog, KW et al) pp scattering: q, q-bar or qq qq-bar (sea quarks)

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

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Antibaryon/baryon ratios at RHIC (pp -1

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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

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

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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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