Energy Scan of Hadron (  0 ) Suppression and Flow in Au+Au Collisions at PHENIX Norbert Novitzky for PHENIX collaboration University of Jyväskylä, Finland Helsinki Institute of Physics, Finland Norbert Novitzky for PHENIX 1

Outlook Introduction Nuclear Modification Factor (R AA ) Flow measurement (v 2 ) Low-energy scan: Motivation Global observables in energy scan v 2 results of  0 Low-energy p+p and Au+Au spectra, x T scaling R AA results of  0 Fractional energy loss studies in low-energy scan Summary Norbert Novitzky for PHENIX 2

Nuclear modification factor Norbert Novitzky for PHENIX 3 A+A varies with impact parameter b p+p

Nuclear Geometry and Hydrodynamic flow Norbert Novitzky for PHENIX 4  RP thermalization larger pressure gradient in plane less yield out more in plane less yield out more in plane x y z Reaction Plane Spatial asymmetry eccentricity Mom. Asymmetry elliptic flow

High p T v 2 versus R AA ( ,p T ) Norbert Novitzky for PHENIX 5 The connection between R AA and v 2 : where The R AA with respect to reaction plane: approximation What is the connection of measure v 2 and R AA ( ,p T ) at high p T ?

Motivation – Suppression in low energy scan Norbert Novitzky for PHENIX 6 Phys. Rev. Lett.101, (2008) Cu+Cu energy scan: Centrality dependence of R AA at √s NN = 200 and 62.4 GeV NO centrality dependence of R AA at √s NN = 22.4 GeV Cu+Cu energy scan: Centrality dependence of R AA at √s NN = 200 and 62.4 GeV NO centrality dependence of R AA at √s NN = 22.4 GeV

dN/d  and dE T /d  energy scan Norbert Novitzky for PHENIX 7 There is no significant change in the centrality dependence of dN/d  and dE T /d  distributions in energy range of 7.7 GeV Au+Au – 2.76 TeV Pb+Pb.

= transverse overlap area of the nuclei. Determined from the Glauber model.  = formation time dE T /d  is multiplied by 1.25 to obtain dE T /dy at SPS energies. Bjorken energy density Norbert Novitzky for PHENIX 8

v 2 in energy scan Norbert Novitzky for PHENIX 9 Phys. Rev. Lett. 105, (2010) Is v 2 saturated in √s NN =39-200GeV? arXiv: From RHIC to LHC the increase is due to the increase of mean-p T

 0 invariant yields of the Au+Au at 62.4 and 39 GeV Norbert Novitzky for PHENIX n 200GeV =8.06 ± 0.03 n 62GeV =10.60 ± 0.03 n 39GeV =13.1 ± 0.1 n 200GeV =8.06 ± 0.03 n 62GeV =10.60 ± 0.03 n 39GeV =13.1 ± 0.1 The minimum bias spectra are fitted with a power-law shape function for p T > 4 GeV/c : 10 In LO of the QCD: To lower √s the contribution from other processes are larger: Running  (Q 2 ) PDF evolution k T smearing Higher-twist phenomena 62.4 GeV 39 GeV arXiv: v1

x T scaling – I. Norbert Novitzky for PHENIX 11 The x T scaling law for the hard scattering region: ArXiv: The n(x T ) should equal to 4 in LO QCD. The isolated photons show the x T scaling with the n(x T )=4.5 The LO QCD is dominant process for the isolated photons

x T scaling – II. Norbert Novitzky for PHENIX 12 Extracting the power with the linear variation of the logarithm of the ratio of the yields at different √s NN : All p+p data shows similar scaling behavior and the n eff (x T ) are comparable The 62.4 and 200 GeV Au+Au data agrees with the p+p data The n eff (x T ) of the 39 and 200 GeV Au+Au show the x T scaling is not working below x T < 0.2 (the end of overlapping region) arXiv: v1

62.4 GeV p+p reference extrapolation Norbert Novitzky for PHENIX 13 Data from PHENIX are available up to p T < 7 GeV/c To extrapolate to higher p T points power- law function was used:  The limit of the fits is vital ––> systematic errors. The systematic uncertainty is calculated from the errors of the power-law fit It agrees well with the CCOR data (ISR) in p T 7-10 GeV/c region For extrapolation the fit above p T >3.5 GeV is used

39 GeV p+p reference Norbert Novitzky for PHENIX 14 Acceptance correction based on PYTHIA8 simulation. The systematic uncertainty of the correction function is calculated based on data to PYTHIA8 comparison. p+p data measured only in fix-target experiment by E0706 at Tevatron with 800 GeV beam energy. ( Phys.Rev.D68:052001,2003 ) The E0706 has different rapidity acceptance -1.0 < y < 0.5 (PHENIX |y|<0.35). Acceptance correction function E0706  PHENIX

R AA in energy scan Norbert Novitzky for PHENIX 15 R AA at 39 GeV shows strong suppression in the most central collision. The 62.4 and 200 GeV R AA data points are comparable for p T > 6 GeV/c. In mid-peripheral collision, 39 GeV data shows so suppression while in higher √s NN the suppression is still significant. The data in most central collision are compared with two calculation of the GLV model, where the difference is the magnitude of the Cronin effect. arXiv: v1

R AA vs p T in all centralities Norbert Novitzky for PHENIX 16 R AA towards more peripheral region shows less suppression and 200 GeV are similar for p T > 6 GeV arXiv: v1

p T averaged Norbert Novitzky for PHENIX 17 R AA in different s NN : GeV are strongly suppressed 39.0 GeV data shows suppression for higher centrality only (N part >100) For p T > 6 GeV/c the 62.4 and 200 GeV data points are comparable arXiv: v1

Fractional Energy-Loss Norbert Novitzky for PHENIX 18 The definition of the energy loss is the “horizontal” shift of the p+p spectrum towards the T AA scaled Au+Au spectra: = 0 T AA *(p+p) Au+Au (0- 10%)  p T /p T Fractional energy loss:

Sloss Norbert Novitzky for PHENIX 19 The fractional energy loss study: 200 GeV exhibits the largest energy loss 62 GeV and 39 GeV data points are in agreement for p T <5 GeV/c arXiv: v1

Sloss in all centralities Norbert Novitzky for PHENIX 20 Same results as the R AA : Towards more peripheral collisions the energy loss is decreasing. In mid-peripheral collision the 39 GeV data have “negative” energy loss. Consistent with R AA >1. arXiv: v1

Summary PHENIX after 10 years of data taking in the inclusive sector: Centrality dependence of global observables do not change from 7.7 GeV to 2.76 TeV. x T scaling: n eff (x T ) for 39 and 200 GeV is very different in p+p and Au+Au  0 v 2 seems to saturate already at 39 GeV GeV  0 R AA was measured in lower energies: The 39 GeV most central is still suppressed 62.4 and 200 GeV are comparable for p T >6 GeV/c 39 GeV shows suppression for Npart>100 Norbert Novitzky for PHENIX 21

Backup Norbert Novitzky for PHENIX 22

Theory vs Data Norbert Novitzky for PHENIX 23

RAA in Bjorken energy density Norbert Novitzky for PHENIX 24 + ALICE data?