1. HBT Radii and Space-Momentum Correlation at RHIC Jingbo Zhang Department of Physics, Harbin Institute of Technology July 11, 2008 @ Hefei

2. July 11, 2008 HBT effect uses to find the size of the fireball from a measurement of two particle correlation function. Two particle correlation function ondistributi particle single :)( on,distributi particle two:),( 11212 2111 212 21 )()( ),( ),( kPkkP kPkP kkP kkC 

3. July 11, 2008 Transverse mass dependence: Au+Au LPSW(05) - DATA in color-- experimentalist’s plot

4. July 11, 2008 Transverse mass dependence: elementary collisions m T dependence in elementary collisions (e.g. OPAL, DELPHI, E735) usually attributed to String fragmentation Resonance contribution Heisenberg uncertainty G. Alexander, hep-ph/0302130 DELPHI - e + e - annihilation

5. July 11, 2008 Transverse mass dependence: p+p p+p: HBT radii decrease with increase of m T STAR data  flow not expected in such a small system as p+p Shuryak: hep-ph/0405066  mT dependence of HBT radii in pp is not generated by the transverse flow, but by the transverse temperature inhomegeneities of hadron-hadron collisions due to the freezing scale – Csorgo et al.: hep-ph/0406042

6. July 11, 2008 Surprising Scaling All p T (m T ) dependences of HBT radii observed by STAR scale with pp although it’s expected that different origins drive these dependences

7. July 11, 2008 RQMD + Correlation after a burner

8. mt-dependence due to collective flow? or space-momentum correlation?

9. July 11, 2008 Single-particle mt-spectra

10. July 11, 2008 Slope Parameter

11. July 11, 2008 Radial Expansion Velocity

12. July 11, 2008 Single-particle mt-spectra II

13. July 11, 2008 HBT Radii without SMC

14. July 11, 2008 Summary The mt-dependence of HBT appears in both heavy-ion and elementary collisions The different mechanism may drive such a dependence. However, it can be considered as a universal reason: space-momentum correlation. The “surprising scaling” of HBT radii suggests that the SMC should be studied in detailed.