Multiplicity Parton Saturation Elliptic Flow. sQGP, Perfect Liquid. EoS

1. High density matter(from SPS and RHIC to LHC)Carlos PajaresUniversidade de Santiago de Compostela Multiplicity Parton Saturation Elliptic Flow. sQGP, Perfect Liquid. EoS Transverse Momentum Suppression Charm, J/Ψ suppression Fluctuations (Multiplicity, Transverse momentum, Balance, LONG range) Percolation of Color Sources Color Glass Condensate XXXV International Meeting on Fundamental Physics 28 de mayo -1 de junio 2007, Santiago de Compostela

2. Energy density versus T/TC. Curve 1-2 quark flavours, curve 2-2 light plus one Heavy flavour and curve 3-3 quark flavours.

3. MULTIPLICITY Extrapolation From lepton-Nucleon and p-A scaling on At LHC energy gives 9.5, i.e. 1800 charged particles per unit rapidity Linear energy data extrapolation gives 6.5, 1200 charged particles String percolation in between Most of the models over 2500.

4. SATURATION OF PARTONS Number of gluons. Size gluons Total Area New Scale QS

5. The whole gluon cascade, (ordered in longitudinal momenta) gives

6. A more detailed treatment, is the BFKL eq • Grows as a power of the energy (Violation unitarity) • Diffusive behaviour, gluons can go inside non-perturbative region

7. Small x, interaction among gluon sources BK equation

8. Solution • At lower x (higher energy) N is large but lower than 1 (solving the unitarity problem) • At small τT, N is small (color transparency) BFKL is OK. • The transition between small τT takes place at a characteristic value τT~1/QS(τ). (solving the infrared diffusion problem) NEW SCALE QS (depends on y an A)

9. ELLIPTIC FLOW

10. We expect Hydrodynamics perfect fluid result is for full thermalized system and a soft EoS LHC?

11. Perfect fluid should have scaling properties Limiting fragmentation Centrality dependence

13. This scaling suggests that the collective flow is at the partonic stage OK with coalescence models

14. Evidence Perfect fluid (interacting at partonic stage, soft EoS, low viscosity, fast thermalization) scaling properties

15. Transverse Momentum Suppression Photons in agreement with perturbative QCD Energy loss by medium induced gluon radiation

16. O.K. with Energy loss dependence on Npart Non photonic electrons Problems: Equally supressed as charged hadrons contrary to predictions (less supressed) Q=14 GeV2/fm

17. Azimuthal distribution of away-side charged hadrons • For central collisions, suppression • of the back jet • The widths of the back-to-back • peaks are independent of • centrality (for pT (asso c)>6 • and 4<pT<6) Possibilities to look for supersonic jets

18. J/Ψ SUPPRESSION hA

19. Low x2 ~ 0.003 (shadowing region) 0 mb 3 mb Data requires smaller σabs at most 3mb (usually σabs= 4.2 mb) No additional suppression seen at RHIC σab=1mb 3 4

20. Thews Eur.Phys.J C43, 97 (2005) Grandchamp, Rapp, Brown PRL 92, 212301 (2004) Regeneration models fit the data. They predict, an increase of J/Ψ at LHC. Lattice studies indicate no suppression of J/Ψ at T=TC, only at T≥2TC. Ψ’ and are supressed at Defining SJ/Ψ,Ψ’ the survival probabilities once is substracted the absorption, as 60% J/Ψ are directly produced and 40% J/Ψ come from decays of Ψ’ and

21. The prediction for LHC is a large suppression of J/Ψ corresponding to the directly produced J/ Ψ. Clear difference at LHC between regeneration and sequential models

22. number of identified charged pion pairs in The width sensitive to hadronization time. Delayed hadronization narrow balance function (stronger correlation in rapidity for the charged particles) Narrowing of the Balance function with Centrality Caveat: In PyTHIA and other models with short hadronization time are able to describe data. The narrowing is only observed at midrapidity

23. MULTIPLICITY FLUCTUATIONS Different Extreme Reaction Scenarios NPTarg fluctuations contribute in target hemisphere (most string hadronic models) NPTarg fluctuations contribute in both hemispheres (most statistical models) NPTarg fluctuations contribute in Projectile hemisphere M. Bleicher M. Gazkzicki, M. Gorenstein arXiv:hep-ph/0511058 • Multiplicity fluctuations sensitive to reaction scenario

24. Reflection, Mixing and Transparency • Significant amount of mixing of particles projectile and target sources

25. String Hadronic Models Projectile hemisphere HSD, UrQMD: V. Konchakovskyi et al. Phys. Rev. C 73 (2006) 034902 HIJING: M. Gyulassy, X. N. Wang Comput. Phys. Commun. 83 (1994) 307 Simulation performed by: M. Rybczynski • String hadronic models shown (UrQMD, HSD, HIJING) belong to transparency class • They do not reproduce data on multiplicity fluctuations

26. PERCOLATION COLOR SOURCES L.Cunqueiro,E.G.Ferreiro,F del Moral,C.P. Results for the scaled variance of negatively charged particles in Pb+Pb collisions at Plab=158 AGeV/c compared to NA49 experimental data. The dashed line corresponds to our results when clustering formation is not included, the continuous line takes into account clustering.

27. FLUCTUATIONS AT RHIC %

28. CLUSTERING OF COLOR SOURCES • Color strings are stretched between the projectile and target • Strings = Particle sources: particles are created via sea qq production in • the field of the string • Color strings = Small areas in the transverse space filled with color field • created by the colliding partons • With growing energy and/or atomic number of colliding particles, the • number of sources grows • So the elementary color sources start to overlap, forming clusters, very • much like disk in the 2-dimensional percolation theory • In particular, at a certain critical density, a macroscopic cluster appears, • which marks the percolation phase transition

29. (N. Armesto et al., PRL77 (96); J.Dias de Deus et al., PLB491 (00); M. Nardi and H. Satz). • How?: Strings fuse forming clusters. At a certain critical density ηc • (central PbPb at SPS, central AgAg at RHIC, central SS at LHC ) a • macroscopic cluster appears which marks the percolation phase transition • (second order, non thermal). • Hypothesis: clusters of overlapping strings are the sources of • particle production, and central multiplicities and transverse momentum • distributions are little affected by rescattering.

30. LONG RANGE CORRELATIONS • A measurement of such correlations is the backward–forward dispersion • D2FB=<nB nF> - <nB> <nF> • where nB(nF ) is the number of particles in a backward (forward) rapidity • In a superposition of independent sources model, is proportional to • the fluctuations on the number of independent sources (It is assumed • that Forward and backward are defined in such a way that there is a rapidity • window to eliminate short range correlations). • Cluster formation implies a decreasing number of independent sources. • Therefore DBF decreases.

31. Sometimes, it is a measured with • b in pp increases with energy. In hA increases with A • Clustering of strings implies a suppression of b

33. Color Glass Condensate As the centrality increases, Qs increases, αs decreases an b increases

34. Kharzeev, Levin, Satz Particle production in high energy is considered as a gluon production in background classical field. The spectrum becomes thermal with during

35. If you can not get rid of the noise…. study the noise Penzias and Wilson RHIC II FAIR LHC