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Published byAvice Hampton Modified over 9 years ago
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Search for Disoriented Chiral Condensates in 158AGeV Pb+Pb Collisions Tapan K.Nayak for the WA98 Collaboration Nucl-ex/9909018
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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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Centauro’s event candidates Cosmic ray –5 + 2 candidates in Brazil-Japan collaboration in Bolivia –1 candidate in Pamir emulsion chanmber ex –Anti-Centauro candidate from JACEE coll 5 Centauro’s candidate Anti-Centauro candidate
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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)
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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.
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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
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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
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N and Nch Correlation DCC model – Model Hep-ph/9812434 –Baked Alaska model?? Upper limit
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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
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Discrete wavelet technique Mother function & Father function definition - phase space
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Discrete wavelet technique segmented Obtain FFC of function f
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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
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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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