1. Summary: QGP Meet’06 The tradition continues: Emergence of Subhashis as the GeNext Organizer-in-Chief: & Establishment of Bedang, Vikash,& Zubayer as the GeNext organizers. Subhashis tried to give an excuse about starting the meeting starting on a Sunday. But this Sunday it was Vishma’s birth-day (Vishma-asthami). And in any case day-names are a western aberration, Indians believed in “tithi”s (number of the day).

2. Ashis Chaudhuri: Valiant Effort to tackle a very tough & challenging problem. Viscousity: Irreversible transfer of momentum from points where velocity is large to where it is small.

9. Raimond Snellings Excellent (Near Complete Review!): Anisotropy of Initial State & Multiple Interactions. The interactions could also be the radiation of gluons/collisions as a jet traversed the plasma. Different from hydrodynanmic flow. Validity of hydrodynamics.- Flow develops early in the collision. Failure of hydrodynamics & recombination model Higher order harmonics. Parton cascade models can give flow only if the parton cross-sections are raised by a factor of 50 or so.

10. Manifestations of Collective Flow (radial and anisotropic) x y x y z x Only type of transverse flow in central collision (b=0) is radial flow –Integrates pressure history over complete expansion phase Elliptic flow (v 2 ), hexadecupole flow (v 4 ), v 6, … caused by anisotropic initial overlap region (b > 0) –More weight towards early stage of expansion. Directed flow (v 1 ), sensitive to earliest collision stage (b > 0) –pre-equilibrium at forward rapidity, at midrapidity perhaps different origin

11. Dependence on the EOS! EoS Q and EoS T (both have significant softening) do provide the best description of the magnitude of the mass scaling in v 2 (p t ) The lattice inspired EoS (EoS qp) in ideal hydro does as poorly as a hadron gas EoS! Pasi Huovinen, arXiv:nucl-th/ 0505036

12. STAR QM2001 Mass dependence Identified particle elliptic flow at low p t –Mass dependence in accordance with collective flow. QGP equation of state (phase transition) provides best description Hydro calculation: P. Huovinen et. al.

13. Top RHIC energies at dip in v 2 Hydro prediction for lower energies v 2 increases? the radial flow increases monotonically with beam energy (pion multiplicity at fixed impact parameter), is the slope of v 2 (p t ) expected to increase for ideal hydro? Where are the 62 GeV calculations? Adapted from P.F. Kolb and U. Heinz, in Quark Gluon Plasma, nucl-th/0305084 Energy dependence of v 2 (p t ) Is the slope of v 2 (p t ) more sensitive to the energy dependence?

14. Munshi Golam Mustafa

20. Comparison to NLO pQCD NLO pQCD with AKK FF relatively better than KKP for the p+pbar data AKK differ from KKP, in the way the light flavor FF are obtained NLO pQCD with Kretzer FF inconsistent with data NLO pQCD with KKP FF inconsistent with the p+pbar data Kretzer differ from KKP, in the gluon to  fragmentation Pawan Kumar Netrakanti

21. Scaling in particle production e + and e - does not have a parton distribution function. There will be a (  s NN ) 2 multiplied to cross-section in e + e - collisions. For p+p collisions n ~ 6.5 for , p (pbar)

22. System expansion: Initial vs Final Size Proton initial size = 0.89 fm from e-scattering Smooth expansion of the system from p+p to Au+Au … but not trivial AuAu: system expands pp (dAu): no or less expansion CuCu 200 AGeV is crucial as it helps In understanding the “missing link” Collisions at 200GeV only STAR PRELIMINARY Debashis Das

23. Proportional to dN ch /d  Freeze out a constant density Also see Ref :CERES PRL Nucl-ex/0207008 STAR PRELIMINARY Constant Freeze out density hypothesis At high energies: Baryon density << Pion density Pion rapidity density  freeze out volume (R s 2 R L )

24. Velocities ( zero at initial time t 0 ) which start differing over extended volume by the end of the QGP phase, become almost identical at the end of hadronic phase. nucl-th/0511079 –Rupa Chatterjee, Evan S. Frodermann, Ulrich Heinz and Dinesh K.Srivastava.. Rupa Chatterjee Fluid velocity along the constant energy density contour for  =  q (for QGP phase),  =  h ( for mixed phase) and  =  f ( for hadronic phase ) for x (y=0) (dashed curve ) and y (x=0) (solid curve).

25. v 2 for thermal photons from 200 AGeV Au+Au collision is shown by the red curve.. Quark and hadronic contributions to v 2 are shown separately. v 2 for pion is also shown in comparison with hadronic v 2. pion v 2 tracks the hadronic v 2. nucl-th/0511079

26. Impact parameter dependence of the elliptic flow Impact parameter are chosen to roughly correspond to collision centralities of 0-10%(b=3 fm), 10-20%(b=5.4 fm), 20-30%(b=7 fm), 30-40% (b=8.3 fm), 40-50% (b=9.4 fm), and 50-60% (b=10.4). nucl-th/0511079

27. Jajati Kesari Nayak

28. Radial expansion? No radial flow!

30. Pradip Kumar Roy Collisional e-loss; Careful evaluation

32. R_AA?

33. Results (contd..) Participant number dependence of electromagnetic fraction of total energy. No significance dependence of electromagnetic fraction on collision centrality.  Tells about the particle production mechanism. STAR Preliminary The centrality dependence of E T /N ch Hydrodynamic flow effect is reflected in the peripheral collisions. If the expansion is isentropic, dN ch /d  will remain constant, whereas dE T /d  will decrease due to the performance of longitudinal work. R. Sahoo

34. Results (contd..) Excitation function of E T /N ch Production of constant transverse energy per charge particle (~ 0.8 GeV) has been observed from AGS to RHIC.  Energy pumped into the system goes for particle production, instead of increasing energy per particle. Recall: Jean Cleymans & Krzysztof Redlich  Freeze-out along /N= 1 GeV.

35. Pseudorapidity Distribution of photons (CuCu 200 GeV) STAR preliminary Upper limit on systematic Error ~ 24% Monika Sharma ?

36. Pseudorapidity Distribution of photons (CuCu 200 GeV) STAR preliminary Upper limit on systematic Error ~ 24% Monika Sharma

37. Comparison of results from PHOBOS (Charge Particles) Charge particle production at forward rapidities are independent of system size Are these outcome of only soft-collisions? Can you check if is smaller than at central rapidity?

38. P. Chakrabory; Also quark number susceptibility

39. Jan-e Alam

42. What about P_T distribution ??????

43. Summary  Detectors at forward rapidity region provide the experiment : centrality and trigger  Forward rapidity region provides rich information on particle production certain universality (species, energy) observed  Forward rapidity region provides information on nuclear stopping, baryon transport and energy for particle production  Forward rapidity provides a chance to scan the QCD phase diagram  Forward rapidity provides the best place to study the possible initial conditions at RHIC : CGC  Forward rapidity provides testing ground for NLO pQCD Measurements at forward rapidity (kinematical limits and detector constraints) are also an experimental challenge Bedanga Mohanty ????

44. Sudhir Bhardwaj; Important step towards measuring v_2

45. MUON Spectrometer aims to measure the signals As a function of centrality –Identify suppression/enhancement patterns As a fuction of the size of the colliding system –Distinguish between normal and anomalous suppression For all onium species –Different survival probabilities probe the temp of the system As a function of p t –Disentangle QGP model With good vertex resolution –Distinguish between prompt and secondary charmonium Verses the reaction plane –Distinguish between Glauber and Comover absorption Together with other QGP signals

46. MUON Spectrometer aims to measure the signals As a function of centrality –Identify suppression/enhancement patterns As a fuction of the size of the colliding system –Distinguish between normal and anomalous suppression For all onium species –Different survival probabilities probe the temp of the system As a function of p t –Disentangle QGP model With good vertex resolution –Distinguish between prompt and secondary charmonium Verses the reaction plane –Distinguish between Glauber and Comover absorption Together with other QGP signals

47. Signal Normalization Drell-Yan above 4 GeV/c 2 (NA38/NA50) –At LHC, D-Y completely drowned into the background from semi- leptonic decay of open charm and open beauty Open Charm (bottom) cross-section –Charm (beauty) thermal production can increase dramatically in QGP with higher temp –Shadowing and/or quenching – suppression of high p t charm/bottom. => Reference dependent on QGP properties Minimum Bias method –Centrality dependence of the efficiency for Dimuon measurement – accuracy => error No Normalization –Careful estimation of systematic error

48. MUON Spectrometer aims to measure the signals As a function of centrality –Identify suppression/enhancement patterns As a fuction of the size of the colliding system –Distinguish between normal and anomalous suppression For all onium species –Different survival probabilities probe the temp of the system As a function of p t –Disentangle QGP model With good vertex resolution –Distinguish between prompt and secondary charmonium Verses the reaction plane –Distinguish between Glauber and Comover absorption Together with other QGP signals Sukalyan Chattopadhyay

49. Signal Normalization Drell-Yan above 4 GeV/c 2 (NA38/NA50) –At LHC, D-Y completely drowned into the background from semi- leptonic decay of open charm and open beauty Open Charm (bottom) cross-section –Charm (beauty) thermal production can increase dramatically in QGP with higher temp –Shadowing and/or quenching – suppression of high p t charm/bottom. => Reference dependent on QGP properties Minimum Bias method –Centrality dependence of the efficiency for Dimuon measurement – accuracy => error No Normalization –Careful estimation of systematic error

50. Production in progress