1. 1 Statistical Model Analysis of K/  and p/  fluctuations in heavy-ion collisions 付菁华 华中师范大学 粒子物理研究所

2. 2 Motivation – Fluctuations & Phase Transition  Particle Number Fluctuations in the Grand Canonical Ensemble Relative Fluctuations ~ V -1 Negligible Phase Transitions Unusually Large Fluctuations

3. 3 Motivation – Thermal Model & Particle Ratios  The Statistical Model very successful in describing particle yield ratios in nucleus - nucleus collisions Whether the hadronic statistical model is equally well in describing particle yield fluctuations ?

4. 4 K/  Fluctuations & Energy Dependence  Strong Energy Dependence Large Fluctuations ？

5. 5 Particle ratio fluctuations ratios of particles volume fluctuations cancel K/  fluctuations : N 1 － number of kaons in an event N 2 － number of pions in an event

6. 6 Statistical model Upper sign for frmions, lower sign for bosons <0 FD =0 MB >0 BE

7. 7 Model Parameters How about volume V ? Not needed for N 1 /N 2

8. 8 Volume From Ref. Nucl.Phys.A 772 (2006) 167, in unit of fm 3

9. 9 Correction NA49 3D acceptance table HIJING simulations The percentage of particles inside the NA49 acceptance table Decreasing Acceptance

10. 10 Correction STAR

11. 11 Results ─ Energy Dependence Data : Full symbols: Model : Open symbols connected with lines:

12. 12 Data : Full symbols: Model : Open symbols: Results ─ Centrality Dependence

13. 13 Conclusion Detector acceptance → increase of K/  fluctuations at the lower NA49 energies Kinematic cuts & tracking efficiency → good description of most central STAR K/  fluctuations & its centrality dependence Thank you !

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16. 16 Particle ratio fluctuations

17. 17 Centrality dependence The volume parameter is decided by asking the average number of K - in the model the same as the STAR measured K - integrated rapidity density