Experimental Results for Fluctuations And Correlations as a Signature of QCD Phase Transitions in Heavy Ion Collisions Gary Westfall Michigan State University, USA Gary Westfall, Quark Matter

Correlations and Fluctuations Depend on previous talk for theoretical justification Look for discontinuities or changes in experimental results for correlations and fluctuations as a function of incident energy K/π Fluctuations Balance Function Net Charge Fluctuations Multiplicity Fluctuations - several approaches p t Correlations RHIC Energy Scan SPS Program Gary Westfall, Quark Matter

K/π Fluctuations Gary Westfall, Quark Matter NA49 Preliminary See talk by Z. Ahammed in Session X See talk by M. Rybczynski, Session X

K/π Fluctuations Gary Westfall, Quark Matter See talk by Z. Ahammed in Session X Torrieri QM06

K/π Fluctuations Scaling with dN/dη Gary Westfall, Quark Matter See talk by Z. Ahammed in Session X Au+Au statistical errors Cu+Cu statistical+systematic errors

Balance Function Charge fluctuations can be studied with several different variables that can be expressed in terms of each other We choose to illustrate charge fluctuations using the balance function Gary Westfall, Quark Matter Bass, Danielewicz, Pratt PRL (2000)

Balance Function Gary Westfall, Quark Matter NA49 Phys. Rev. C 76, Balance functions for Pb+Pb at s NN ½ = 6.3 to 17.3 GeV Balance functions for Au+Au at s NN ½ = 20 to 200 GeV Data Shuffled Au+Au 200 GeV STAR, QM 02, QM 04

Balance Function Gary Westfall, Quark Matter NA49 Phys. Rev. C 76, Large W means narrow balance function

Net Charge Fluctuations at RHIC Gary Westfall, Quark Matter See poster by M. Sharma

Net Charge Fluctuations at RHIC Gary Westfall, Quark Matter See poster by M. Sharma The slope in p+p, Cu+Cu and Au+Au depends on the correlation length: the shorter the correlation, the larger the slope The distributions indicate that the correlation length is shorter for central collisions and for larger systems, in agreement with the observed reduction of the width of the balance function

Net Charge Fluctuations at the SPS Gary Westfall, Quark Matter NA49 PRC 70, (2004)

Multiplicity Fluctuations at the SPS Gary Westfall, Quark Matter NA49, [nucl-ex] % most central Scaled to 4π

Multiplicity Fluctuations at RHIC Gary Westfall, Quark Matter PHENIX, PRC 76, (2007)

Multiplicity Fluctuations at RHIC Gary Westfall, Quark Matter PHENIX, PRC 76, (2007) See talk by K. Homma in Session X

Forward/Backward Multiplicity Correlations Gary Westfall, Quark Matter See talk by B. Srivistava Session XIX See poster 220 by T. Tarnowsky

Energy Dependence of F/B Multiplicity Fluctuations Gary Westfall, Quark Matter Central Au+Au 0 – 10% 200 GeV 62.4 GeV Long range correlations are an indicator of multiple elementary elastic collisions Long range correlations decreases as the incident energy is decreased STAR preliminary See talk by B. Srivistava Session XIX See poster 220 by T. Tarnowsky

p t Fluctuations Gary Westfall, Quark Matter Adamova et al., CERES Miskowiec for NA49, CPOD 2007

p t Fluctuations Gary Westfall, Quark Matter Adamova et al., CERES Calculate for pairs within a given range of Δ ϕ and multiply by dN/dη The region of 30° < Δ ϕ < 60° is free from effect such as HBT and jets and may be a fruitful region to search for discontinuities as a function of incident energy

RHIC Energy Scan Energies as low as s NN 1/2 = 4.5 GeV (10 AGeV fixed target) Gary Westfall, Quark Matter (GeV)(MeV) Min Bias BBC Rate (Hz) Days/ Mevents Number Of Events Number of beam days (5)9(4.6)545(23+2) (50)4(0.5)520(3+1) (150)2(0.2)510(1+1) (300)1.5(<1)5(>5)7.5(1+1) (1000)0.5(<1)5(>50)2.5(1+1) 18220>100(>1000)0.25(<1)5(>50)1.5(1+1) 28150>100(>1000)0.25(<1)5(>50)1.5(1+2) T. Satogota, RHIC

NA 49/61 Future Program Gary Westfall, Quark Matter M. Gazdzicki

Proposed Energy and Mass Scans Gary Westfall, Quark Matter

Addition of TOF to STAR Gary Westfall, Quark Matter STAR will add TOF for Run 10 The TOF will provide excellent particle identification for π, K, and p for a large fraction of the measured particles event-by-event Improved K/π fluctuation measurements Improved balance functions with identified π, K, and p See talk by G. Odyniec, session XXIV P. Sorensen Charged pions and kaons 0.2 < p t < 0.6 GeV/c

Conclusions 1 We have experimental results for correlations and fluctuations covering incident energies where one might expect effects from the QCD critical point and we have some hints in the However, the results are not conclusive In particular, we have several different variables, acceptances, and interpretations that need to be unified We need to measure correlation fluctuation variables over the broadest range in incident energy and system size Gary Westfall, Quark Matter

Conclusions 2 The SPS and RHIC scans will provide an excellent opportunity to study the QCD critical point SPS system/energy scan will add a large number of points in T/μ B space in the search for the critical point We also look forward to correlations and fluctuations related to the QCD phase transition at GSI/FAIR Gary Westfall, Quark Matter

Extra Slides Gary Westfall, Quark Matter

Balance Function with Identified Pions Gary Westfall, Quark Matter Charged pion pairs 0.2 < p t < 0.6 GeV/c The excellent particle identification for π, K, and p for a large fraction of the measured particles event-by-event will allow new kinds of event-by-event measurements such as the balance function with identified particles

Relation between Net Charge Fluctuations and the Balance Function Gary Westfall, Quark Matter Jeon and Pratt PRC 65, (2002)

HBTHBT Gary Westfall, Quark Matter

HBTHBT Gary Westfall, Quark Matter