Strangeness production in HIC

1. Strangeness production in HIC Evgeni E. Kolomeitsev open Matej Bel University Banska Bystrica hidden

2. Why do we love strangeness? Strangeness’ Hall of Fame 2. Temporal aspects of the strangeness production: Where does the strangeness comes from? 3. OZI rule, phi catalysis

3. Strangeness in HIC: Hall of Fame most popular pictures (personal choice)

4. 1998 Antikaon production KaoS Collaboration 2006 in-medium modifications of kaon properties

5. Kaon production NA49 Collaboration The Horn Difficult to reproduce: transport generators (RQMD, HSD) hydro calculations statistical model Successful interpretation within the Statistical model of the early stage [Gazdzicki & Gorenstein] Evidence for a QGP phase transition?

6. Phi meson puzzle 1997-1999 NA49/NA50 Collaborations Difference of phi yields in Pb+Pb@158 AGeV NA49 (K+ K-) and NA50 () experiments rescattering of decay products 2006-2008 CERES ’06 in Pb+Au@158AGeV Phi yield via e+e-agrees with NA49 data NA60 ’08 in In+In@158 AGeV;  Phi yield is higher than in NA49

7. rescattering+regeneration ! decay-product rescattering stable particles resonances Resonance production at RICH Thermal model THERMUS [Wheaton & Cleymans ’04] STAR vs. Thermal model Continuous freeze-out [Grassi, Kadama, Knoll ..] [STAR Au+Au@ 200 AGeV: R. Witt JPG 34 (2007) S921]

8. Why do we like strange particles? • particles with a “tag” (new quantum number) • mass gap • associated particle production The strangeness production in a HIC is controlled by • available energy (energy density) and mass gap (in medium) • - temporal evolution of a HIC (fireball lifetime)

9. open strangeness

10. energy vs. time We try hadronic scenario; intrinsically assume non-equilibrium of strangeness. [B.Tomasik,E.E.K, nucl-th/0512088; EPJC 49 (2007)]

11. annihilation rate production rate expansion rate flavour kinetic calculation with an ansatz for the fireball expansion parameterizethe space-time evolution a data/experience (HBT, spectra) driven ansatz for expansion We want to explore various ansatzes and their impact on result K+ and K0 evolution calculated from calculate from known cross-sections and evolved densities

12. explicit kinetic calculation: K+, K0, K*+, K*0 (vacuum properties) • kaons in thermal equilibrium (until decoupling) • chemical equilibrium: non-strange species (, N, , , N*,…) • relative chemical equilibrium: S<0 sector ( K-, , , , ) • no antibaryons assumed at these energies in red: well-defined cross sections

13. acceleration + power-law expansion • explore a range of values for the model parameters • at the end power-law scaling suggested by HBT

14. fix the final state FO, B,FO, I,FO obtained from FO analysis [Becattini et al., PRC 69 (2004) 024905] we choose the initial 0 and the lifetime T correct K+ abundance correct complete chemical composition correct T and  initial K+ content estimated from pp (pn, nn) collisions initial S<0 species balance strangeness and are relatively equilibrated we certainly end up with correct FO, B,FO, I,FO but temperature depends on strangeness production

15. fixed matching point some variation fixed fixed for a given run [FO analysis] for a given run the power-law prescription is realized only towards the end

16. exp. data

17. final temperatures is close to that of Becattini et al. the whole final chemical composition is correct!

19. The K+ horn can be interpreted as a rise and fall of the fireball lifetime The time needed for a strangeness production is about 15-20 fm/c. In hydro the typical expansion time is <10 fm/c.

20. hidden strangeness

21.  need 3 gluons to form a white hadron state Okubo-Zweig-Iizuka suppression rule the interactions of a pure (ss) vector state with non-strange hadrons are suppressed 1/Nc counting  3 times smaller than expected from pure octet-singlet mixing:  coupling due to the anomaly Experiment:

22. f f Y N Phi production in reactions involving strange particles is not OZI suppressed! strangeness hides into  a new type of the  production mechanism catalytic phi meson production strangeness content does not change

23. traditional catalytic dominant source of phi considered so far typical hadronic cross sections [Andronic, PBM, Stachel, NPA 772, 167]

24. Cross section of catalytic reactions isospin averaged cross sections Cross sections ~ 1 mb much larger than  N-> N

25. follow follow Simple model for strangeness production Diff.eq. for K^+ production annihilation neglected, K<<B thermal weights scales with t0 !

26. N ->  N catalytic reactions Red lines scale with t0 !!! Catalytic reactions can be competitive if T>110 MeV and t_0>10 fm Phi production

27. fireball volume the mean number of projectile participants units of length and time [Russkikh, Ivanov, NPA 543 (1992)] # of strange particle # of non-strange particles # of kaons # of phis Centrality dependence Consider a collision at some fixed energy ( - reaction rate) catalytic reactions

28. Centrality dependence fit coefficients to data point [E917 Collaboration, PRC 69 (2004) 054901] Au+Au@11.7 AGeV The catalytic reaction contribution can be about 30%-40% for Npp=A.

29. the root mean square of the distribution If  are produced in Phi rapidity distribution The distributions can be fitted with a sum of two Gaussian functions placed symmetrically around mid-rapidity [NA49 Collaboration, PRC 78 (2008) 044907]

30. (new) (old) Assume: the rapidity distributions of particles do not change after some initial stage.The absence or weakness of acceleration and diffusion processes. The collision kinematics is restricted mainly to the exchange of transverse momenta . The rapidity distribution of s produced in the reaction 1+2 ->  +X is roughly proportional to the product of rapidity distributions of colliding particle species 1 and 2.

31. Catalytic phi production can be competitive if T>110 MeV and t_0>10 fm can be seen in centrality dependence of the phi yield determine the width of the phi rapidity distribution

32. What to measure? just K+ mesons – deadly boring K+ and K-- mesons – boring kaons and  – check for strangeness conservation kaonsmesons and  and  – check for strangeness conservation isospin kaons mesons and hyperonsand – interesting kaons mesons and hyperons and and – very interesting strangeness dynamics kaons mesons and S=1,2 hyperons and and hyperon resonances – exciting