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Search for Disoriented Chiral Condensates in 158AGeV Pb+Pb Collisions

Search for Disoriented Chiral Condensates in 158AGeV Pb+Pb Collisions. Tapan K.Nayak for the WA98 Collaboration Nucl-ex/9909018. Centauro’s Signal. Centauro events Large numbers of hadrons Little apparent electromagnetic energy (no pi0) High hadronic pt 0.35+-0.15GeV.

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Search for Disoriented Chiral Condensates in 158AGeV Pb+Pb Collisions

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  1. Search for Disoriented Chiral Condensates in 158AGeV Pb+Pb Collisions Tapan K.Nayak for the WA98 Collaboration Nucl-ex/9909018

  2. Centauro’s Signal • Centauro events • Large numbers of hadrons • Little apparent electromagnetic energy (no pi0) • High hadronic pt 0.35+-0.15GeV

  3. Centauro’s event candidates 5 Centauro’s candidate • Cosmic ray • 5 + 2 candidates in Brazil-Japan collaboration in Bolivia • 1 candidate in Pamir emulsion chanmber ex • Anti-Centauro candidate from JACEE coll Anti-Centauro candidate

  4. No Centauros • Cosmic ray • No centauros in emulsion chamber at Kanbala, at Mt.Fuji. • China-Japan coll, upperlimit 3%(>100TeV,95%CL) • Accelarator • CERN UA5 etc : negative results up to sqrt(s)=900GeV • FERMILAB MINIMAX(T864)

  5. Disoriented Chiral Condensates • Cantauros event’s source ??? • Chiral symmetry • Chiral symmetry is broken when hadronization. • Pi0 to total pi ratio • Pi = isospin zero • Binominal distribution • largeN -> Gaussian dist • HI collisions • Rapid expansions in the longitudinal direction leads domains of the unconventionally oriented vacuum configuration.

  6. WA98 Experiment • Silicon Pad Multiplicity Detector(SPMD) • 32.8cm downstream • 2.35<  < 3.75 • Photon Multiplicity Detector(PMD) • 21.5m downstream • 2.9<  < 4.2 • Plastic scinti + 3X0 lead conveter, 28segment • 66k central events • 5% central determined by midrapidity calorimeter(MIRAC) • Common coverage of PMD and SPMD was considerd

  7. N and Nch Correlation • hep-ex/9802019 • Event by event analy • N and Nch • Correlation axis(Z) has been obtained by fitting by second order polynomial. • Closest distance(Dz) has been calculated numerically • Dz represents the relative fluctuation of N and Nch

  8. N and Nch Correlation • DCC model •  Model • Hep-ph/9812434 • Baked Alaska model?? • Upper limit

  9. N and Nch Correlation • Smaller  segmented into 2,4,8,16bins • Broader distribution of Sz • Fig1(b), the rms deviations of data differ significantly(???) • This is non-statistical fluctuations for bin sizes>45deg

  10. Discrete wavelet technique • Mother function & Father function •  definition • - phase space

  11. Discrete wavelet technique •  segmented • Obtain FFC of function f

  12. Discrete wavelet technique • 2,4,8,16 resolution scale • J=3,4 consistent • J=1,2 clear difference from mixed event and Venus+Geant • FFC(j=3,4) is obtained from FFC(j=1,2) • Difference is due to the fluctuations

  13. Conclusion • Two independent ana of - phase space • Presence of non statistical fluctuations • This could be effected by many different physics effects • Attempts are being made to explain this assuming the fluctuations to be solely due to the presence of localized domains of DCC

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