FLUCTUATION as a signal of QGP:

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FLUCTUATION as a signal of QGP Present
Experimental Results
AuAu at RHIC

• Large number particles in each event (at SPS,
  RHIC and LHC) allows for Event-by-Event physics
• Study of Event-by-Event Fluctuations become quite
  relevant.

Tapan Nayak Jan 6, 2003
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Event-by-Event Fluctuations
Thermodynamic Properties of Matter Thermodynamic Properties of Matter Thermodynamic Properties of Matter
Specific heat Fluctuation in Temp. or lt pT gt PRL 75 (1995) 1044 L. Stodolsky Phys. Lett. B423 (1998) 9 E Shuryak
Compressibility Multiplicity Fluctuation (DN)2 lt (N - lt N gt)2 PLB 430 (1998) 9 S. Mrowczynski
Study of thermodynamic quantities (or fluctuations in exptl. observables) can shed light on possible existence of phase transition and its nature. Study of thermodynamic quantities (or fluctuations in exptl. observables) can shed light on possible existence of phase transition and its nature. Study of thermodynamic quantities (or fluctuations in exptl. observables) can shed light on possible existence of phase transition and its nature.
Chiral Symmetry Restoration gt Formation for Disoriented Chiral Condensates Chiral Symmetry Restoration gt Formation for Disoriented Chiral Condensates Chiral Symmetry Restoration gt Formation for Disoriented Chiral Condensates
Fluctuation in number of neutral to charged pions Fluctuation in number of neutral to charged pions Fluctuation in number of neutral to charged pions

• J.D. Bjorken 1992
• Rajagopal Wilczek 1993

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Tricritical point of QCD phase diagram
Stephanov, Rajagopal and Shuryak PRL 81 (1998)
Similar to behavior of strange quark mass and
temperature in m-T plane
At the TRICRITICAL POINT singularities in
thermodynamical observables gt LARGE
EVENT-BY-EVENT FLUCTUATIONS
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Disoriented Chiral Condensates (DCC)
Normally Each of the pion flavors are roughly
equally populated. We define
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MEASURES OF FLUCTUATIONS
Measure Proposed by References
s2/mean of the Gaussian, ratios Baym Heiselberg Jeon Koch PLB 469 (1999) 7 Phys. Rep. 351 (2001) 161 PRL 83 (1999) 5435
Wavelets Huang, Sarcevic, Thews X-N Wang (for DCC) PRD 54 (1996) 750
Correlator Stephanov, Rajagopal, Shuryak PRD 60 (1999) 114028
Fluctuation in conserved Quantities Jeon, Koch Asakawa, Heinz, Muller PRL 85 (2000) 2076 PRL 85 (2000) 2076
Balance Functions Bass, Danielewicz,Pratt PRL 85 (2000) 2689
fpT Gazdzicki, Mrowczynski Z. Phys. C54 (1992) 127
ndyn Pruneau, Gavin ,Voloshin nucl-ex/0204011
Space-time evolution of fluctuations are
important!
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SPMD 2.35 lt h lt 3.75
PMD 2.9 lt h lt 4.2
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158.A GeV PbPb at SPS
STATISTICAL DYNAMICAL
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Multiplicity Fluctuation
Multiplicity distributions are GAUSSIANS
for narrow bins in centrality. The physics
(statistical dynamical) is in the width of the
distribution. The amount of fluctuation
w s2/ lt N gt
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Multiplicity Fluctuations for various centralities
Charged Particles
Peripheral
Central
Data agree fairly well with participant model
calculations
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Fluctuations of Ch. particles vs. Photons
Single event display gt Charged particles
superimposed on photons
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Ng vs. Nch FLUCTUATIONS

• Top 5 central events ONLY
• Bins in f 1,2, 4, 8, 16
• Discrete Wavelet Analysis
• Correlation Analysis

Localized phase fluctuations
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RMS WIDTHS OF DATA compared with GEANT 4-types
of MIXED EVENTS

• Data widths gt M1
• gt Presence of localized
• fluctuations in
• Ng
• Nch
• Correlated
• fluctuation

X
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Formation of DCC upper limits
Global DCC
0-5 central

• Localized fluctuations decrease
• from central to peripheral.
• Upper limit for DCC-like
• localized fluctuations 3x10-3
• for central collisions.

1. Phys.Lett.B420169-179,1998 2.
Phys.Rev.C64011901,2001 3. nucl-ex/0206017, to
be published in PRC Krzywicki Serreau Phys.
Lett.B 448 (1999) 257
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RHIC Results so far
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PMD In STAR experiment at RHIC
Photon Multiplicity Detector (PMD)

• Preshower Detector, fine granularity
• Two planes Veto Pre-shower
• Total no. of cells 82,944
• Gas detector with hexagonal cells
• h Coverage 2.3 3.9
• Cell c.s. 1.0 cm2, depth 0.8 cm
• Area of the detector 4.2m2

PMD in Full STAR setup
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In ALICE Experiment at CERN
Front View of PMD

• Gas detector with
• hexagonal cells.
• 170,000 honeycomb
• cells (each of 0.22
• cm2 area).
• Two planes
• Total area 1.8m2
• for each plane.

MUON ARM
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SUMMARY

• Study of Fluctuations of various quantities
  provides a powerful
• means of observing QCD phase transition.
• Measurement at SPS gives
• no evidence of non-statistical fluctuation
• no indication of e-by-e correlated fluctuations
  (DCC-type)
• Upper limits of DCC production is set at 90
  C.L.
• Event-by-event physics and fluctuations should
  be studied along
• with other signals as functions of centrality
  of the collision and
• various colliding systems.

QCD phase transitions can be studied thru
anomalous fluctuations and correlations just as
in real life situations.