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Chiral Restoration? DCC  pion fluctuations … but QCD has more than two flavors

Strange Fluctuations at RHIC Sean Gavin Wayne State University. Chiral Restoration? DCC  pion fluctuations … but QCD has more than two flavors. I. DCC with 3 flavors – correlations of K s 0 and K  strange correlations from n DCC “domains”

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Chiral Restoration? DCC  pion fluctuations … but QCD has more than two flavors

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  1. Strange Fluctuationsat RHICSean Gavin Wayne State University Chiral Restoration? DCC  pion fluctuations … but QCD has more than two flavors I. DCC with 3 flavors – correlations of Ks0and K • strange correlations from n DCC “domains” • robust observables, thermal background II. “conventional” kaon isospin fluctuations • wounded nucleons, HIJING, UrQMD • isospin fluctuations probe models with J. Kapusta with M. Abdel Aziz

  2. Strange Isospin Fluctuations: Why? “2 +1” flavor QCD – transition depends on strange quark mass theory: Pisarski & Wilczek; Gavin, Gocksch & Pisarski; … lattice: Brown et al.; Schmidt, Karsch & Laermann … SPS  + + enhancement explained by many small strange DCC? • topological baryon production: Kapusta & Wong; Ellis, Heinz & Kowalski •  model of chiral symmetry breaking: Kapusta & Srivastava  Kapusta's talk Polyakov Loop Condensate model of confinement? • many small domains  RHIC pT fluctuations: Pisarski & Dumitru • K/ enhancement: Scavenius, Dumitru & Lenaghan consequence: small strange domains  kaon fluctuations

  3. 2+1 flavors  Kaon Fluctuations? QCD: chiral symmetry broken by condensate below Tc condensate for two light flavors: neutral v. charged pion fluctuations  = neutral pion fraction u, d + strange quark: pion and kaon fluctuations K= neutral kaon fraction Randrup & Schäffner-Bielich fp 1/3 fK 1/2

  4. DCC thermal Kaon Isospin Fluctuations S.G. & J.Kapusta measure Ks0 and charged K+ characterize fluctuations of fK= N0/ Ntot by variance: single kaon DCC uncorrelated thermal source

  5. Dynamic Isospin Fluctuations experiment: measure Ks0, K+ with different efficiencies efficiency  = measured/observed multiplicities STAR: 0 ~ 10-20% for Ks0<< c ~ 70% for K+ dynamic isospin fluctuations • robust: independent of efficiencies C. Taylor et al; Pruneau, Gavin and Voloshin • vanishes for thermal sources, uncorrelated sources • nonzero for DCC

  6. Many Small Domains • SPS - + + data  many domains, size ~ 2 fm Kapusta & Wong • WA98 – no big pion signals resolved •  model predictions S.G., Gocksch & Pisarski, … • n pion domainsAmado & Lu; Chow & Cohen n kaon domainsS.G. & Kapusta Gaussian for n > few variance

  7. DCC + Thermal Source • S.G. & J.Kapusta • fraction  of DCC kaons • variance • dynamic fluctuations • only DCC contributes • can be positive or negative ASK: what about non-equilibrium effects?

  8. “Conventional” Isospin Fluctuations Abdel Aziz & S.G. • AA collision – superposition of NN subcollisions • nonequilibrium fluctuations in rapidity interval: • NN level – string fragmentation, resonances • AA changes – rescattering, resonance abundance • pp simulations • wounded nucleon model, M participants *preliminary

  9. HIJING Dynamical Fluctuations HIJING simulations for Au+Au at 200 AGeV -0.5 < y < 0.5 Wounded nucleons ok agreement with wounded nucleon model dyndifferent for Kch Ks0 Abdel Aziz & S.G. K+Ks0 K Ks0 participants, M

  10. Conventional Isospin Fluctuations HIJING, UrQMD: Au+Au at 200 AGeV, -0.5 < y < 0.5 similarcharge fluctuations different isospin fluctuations +   K+K participants Abdel Aziz & Gavin • UrQMD  HIJING  wounded nucleons • different signs forKchKs0 • same sign for all centralities participants

  11. DCC from Collisions threshold for DCC onset take for b0 ~ 6 fm, 10 DCC, –0.5 < y < 0.5 dynamic fluctuations sensitive to DCC signal: sign change compare to  not sensitive participants

  12. Pion Isospin Fluctuations • HIJING, URQMD • Au+Au 200 AGeV, -0.5 < y < 0.5 • Wounded nucleons • DCC: • photon-p fluctuations identify DCC • no need to reconstruct 0 • similar sensitivity to kaons pg pg participants, M

  13. Summary: Observing Kaon Fluctuations Ks0 K correlations test 2+1 flavor DCC?S.G. &Kapusta • SPS  data  many small strange DCC? Kapusta & Wong • small domains from Polyakov loop condensate Pisarski & Dumitru Robust observables compare unlike particles • charged particles, baryons Pruneau, Voloshin + S.G. • kaon fluctuations Dynamical isospin observable • dynamic fluctuations shows DCC effect • distinguishes conventional dynamical models – unlike charge fluctuationsAbdel Aziz + S.G. (in progress)

  14. Multiple Collision Models AA collision – superposition of M nucleon subcollisions robust variance, covariance depends on subcollision fluctuations dynamic isospin observable independent of M

  15. pz q py px Disoriented Chiral Condensate 2 flavor QCD, massless u and d quarks -- chiral symmetry above Tc condensate below Tc breaks symmetry chiral rotations nonequilibrium: T drops below Tc transient pion fields condensate field  isospin fluctuations neutral vs. charged pions

  16. HIJING Covariance 10,000 HIJING events Au+Au at 200 AGeV -0.5 < y < 0.5 Wounded nucleons HIJING scales like wnm large contribution from multiplicity fluctuations

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