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Transverse and Longitudinal Dynamics at RHIC

Transverse and Longitudinal Dynamics at RHIC. Paweł Staszel, Marian Smoluchowski Institute of Physics Jagiellonian University. SQM 2007 Levo č a, 24–29.06.2007. Outline. General (bulk) characteristics of nucleus-nucleus reactions.

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Transverse and Longitudinal Dynamics at RHIC

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  1. Transverse and Longitudinal Dynamics at RHIC Paweł Staszel, Marian Smoluchowski Institute of Physics Jagiellonian University SQM 2007 Levoča, 24–29.06.2007

  2. Outline • General (bulk) characteristics of nucleus-nucleus reactions. • Nuclear effects at mid- and forward rapidity (RAA and p/) • Elliptic Flow • Testing pQCD at large rapidities in p+p • Summary.

  3. Total E=25.72.1TeV 72GeV per participant Particle production and energy loss Energy density: Bjorken 1983 eBJ = 3/2 (<Et>/ pR2t0) dNch/d assuming formation time t0=1fm/c: >5.0 GeV/fm3 for AuAu @ 200 GeV >4.4 GeV/fm3 for AuAu @ 130 GeV >3.7 GeV/fm3 for AuAu @ 62.4 GeV

  4. BRAHMS NA49 At 200GeV created matter is picked at y=0 AGS primary matter is concentrated around y3 (y2.0) Primary versus produced matter • longitudinal net-kaon evolution similar as net-proton in |y|< 3 at RHIC (AuAu @ 200 GeV) • strong “association”: net-kaon / net-lambda /net-proton?

  5. Nuclear Modification Factor Yield(AA) RAA = NCOLL(AA)  Yield(NN) Scaled N+N reference AuAu @200GeV Nuclear effects RAA<1 Suppression relative to scaled NN reference

  6. Energy and system dependent nuclear modification factors at h~0 and 1 pT [GeV/c] • R AuAu (200 GeV) < RAuAu(63 GeV) < RCuCu(63 GeV) for charged hadrons • p+p at 63 GeV is ISR Data (NPB100), RHIC-Run6 will provide better reference

  7. RAuAu(y=0) ~ RAuAu(y~3) for central Au+Au at √s = 200 GeV • R AuAu (y=0) ~ RAuAu(y~3) for pions and protons: accidental? • Rapidity dependent interplay of Medium effect + Hydro + baryon transport

  8. Interpretation of suppression at forward y • G. G. Barnafoldi et al. Eur. Phys. J. C49 (2007)333 • pQCD + GLV fit to RAA→ L/λ • assuming λ=1fm • L~4/1.5fm at mid/forward rapidity

  9. Strong energy absorption model - static 2D source. (Insprired by A.Dainese (Eur.Phys.J C33,495) and A.Dainese , C.Loizides and G.Paic (hep-ph/0406201) ) • Parton spectrum using pp reference spectrum • Parton energy loss dE ~ q.L**2 • q adjusted to give observed RAA at h~1. The change in dN/dh will result in slowly rising RAA . The modification of reference pp spectrum causes the RAA to be approximately constant as function of h .

  10. Strong rapidity dependence CuCu data consistent with AuAu for the same Npart pbar/-scaling with Npart sNN=200GeV pp pp

  11. At y~0 negative and positive ratios behave similar K-/-decreases by factor of 2/3 when going from y~0 to y~3, however, enhancement over p+p increases. In accord to pbar/- K+/+at y~0 is similar that at y~3, however, enhancement over p+p increases K/ ratios at y~1 and y~3, Au+Au @200GeV K+/+ K-/-

  12. suppression Cronin enhancement Examine d+Au at all rapidities I. Arsene et al., BRAHMS PRL 93 (2004) 242303.

  13. RdAu centrality dependence for + BRBRAHMS PRELIMINARY 40-80% 20-40% 0-20% y=3.0 At y~3 RdAu for +reflects stronger suppression for more central collisions – same trend as for h-

  14. Differential flow at forward rapidity Hydro calculations (red symbols) by T. Hirano

  15. p+p at 200GeV – examine pQCD at large y PRL 98 (2007) 252001

  16. Large y: pQCD versus data μ=μF=μR=pT. CTEQ6 parton distribution functions. KKP modified to obtain FFs for specific charges: Dπ+u = (1+z)Dπ0u ; Dπ-u = (1-z)Dπ0u AKK reproduce STAR p+pbar at y~0, at large y gluons contribute in > 80% KKP under predict p+pbar by factor of 10.

  17. Does baryon number transport extend to high pT? pT y yb=-5.4 yb=5.4

  18. p+p @ 62GeV results BRAHMS PRELIMINARY

  19. Summary for A+A • K/p reflects stronger enhancement at forward rapidity as compared to mid-rapidity. • K-/- drops when going form mid to forward rapidity whereas K+/+ shows weak dependency on rapidity • RdAu for + decreases with increasing centrality and for • 0-20% centrality reaches value of ~0.5 (3 < pT < 4)

  20. Summary for p+p • At 200 GeV pbar/p is below 0.1 at high pT (~4GeV/c) and y~3. • This strong asymmetry in p and pbar production can not be described by known FFs. • Explanation of data require new mechanism that will be able to transport baryon number to high pT (recombination soft-shower?) • At the same y but lower energy (62GeV) the effect is stronger by an order of magnitude (both for kaons and protons)

  21. The BRAHMS Collaboration I.Arsene7, I.G. Bearden6, D. Beavis1, S. Bekele6 , C. Besliu9, B. Budick5, H. Bøggild6 , C. Chasman1, C. H. Christensen6, P. Christiansen6, R. Clarke9, R.Debbe1, J. J. Gaardhøje6, K. Hagel7, H. Ito10, A. Jipa9, J. I. Jordre9, F. Jundt2, E.B. Johnson10, C.E.Jørgensen6, R. Karabowicz3, N. Katryńska3, E. J. Kim4, T.M.Larsen11, J. H. Lee1, Y. K. Lee4, S.Lindal11, G. Løvhøjden2, Z. Majka3, M. Murray10, J. Natowitz7, B.S.Nielsen6, D. Ouerdane6, R.Planeta3, F. Rami2, C. Ristea6, O. Ristea9, D. Röhrich8, B. H. Samset11, D. Sandberg6, S. J. Sanders10, R.A.Sheetz1, P. Staszel3, T.S. Tveter11, F.Videbæk1, R. Wada7, H. Yang6, Z. Yin8,and I. S. Zgura9 1Brookhaven National Laboratory, USA, 2IReS and Université Louis Pasteur, Strasbourg, France 3Jagiellonian University, Cracow, Poland, 4Johns Hopkins University, Baltimore, USA, 5New York University, USA 6Niels Bohr Institute, University of Copenhagen, Denmark 7Texas A&M University, College Station. USA, 8University of Bergen, Norway 9University of Bucharest, Romania, 10University of Kansas, Lawrence,USA 11 University of Oslo Norway 48 physicists from 11 institutions

  22. BACKUP SLIDES

  23. Schematic view of jet production hadrons leading particle q q leading particle High pt suppression  jet quenching • Particles with high pt’s (above ~2GeV/c) are primarily produced in hard scattering processes early in the collision • p+p experiments  hard scattered partons fragment intojets of hadrons • In A-A, partons traverse the medium  Probe of the dense and hot stage • If QGP partons will lose a large part of their energy (induced gluon radiation)  suppression of jet production  Jet Quenching Experimentally  depletion of the high pt region in hadron spectra

  24. BE:  = 3/2 (<Et>/ S0) dNch/d Sis transversearea of overlapping region <Et>derived from  and K spectra New pp data @62GeV will allow for various comparisons at the same rapidities preliminary RAA versus centrality • Similar level of suppression for central collisions • At forward rapidity RAA shows stronger rise towards peripheral coll. (surface -> volume emission) preliminary

  25. RdAu and RAA for anti-protons and pions @200 BRAHMS PRELIMINARY • suppression for - but stronger for AuAu • both RdA and RAA show enhancement for p-bar

  26. How s= ¼ u,d will work for hyperons? Hbar/H = (pbar/p)3/4for Lambdas = (pbar/p)1/2for Xis = (pbar/p)1/4for Omegas K-/K+ and antihyperon/hyperon K-/K+ = exp((2s - 2u,d)/T) pbar/p = exp(-6u,d/T) s=0  K-/K+ = (pbar/p)1/3 Fit shows that K-/K+ = (pbar/p)1/4  s= ¼ u,d

  27. Statistical model and s vserus u,d Fits with statistical model provide similar u,d/s ratio with weak dependency on y. B. Bieron and W. Broniowski Phys. Rev. C75 (2007) 054905 This result is consistent with local net-strangeness conservation red line - s = 0 black line – fit to BRAHMS data

  28. Control measurement: d+Au @ sNN=200 Excludes alternative interpretation in terms of Initial State Effects  Supports the Jet Quenching for central Au+Au collisions + back-to-back azimuthal correlation and jet structure by STAR and PHENIX

  29. P/pi ratio: p+p @ sNN=62

  30. Nuclear modification factors (RCP, RAuAu) for p,K,p at y~3.1 • Suppression for pions and kaons: RAuAu:  < K < p • RAuAu ≠ Rcp (<Ncoll>,<Npart> for 40-60% ~ 70,56)

  31. dN ddptd dN 1 ddpt 2 = (1 + 2v1cos + 2v2(,pt)cos2) Flow at forward rapidity • missing low-pt fraction is important for integrated v2 from FS (can explain about 20% change)

  32. Constituent quark scaling

  33. RAuAu 200 GeV Cronin enhancement suppression at high pT significant medium effects BRAHMS, PRL 91, 072305 (2003)

  34. Summary • Large hadron multiplicities  Almost a factor of 2 higher than at SPS energy( higher )  Much higher than pp scaled results( medium effects) • Identified hadron spectra Good description by statistical model  Large transverse flow consistent with high initial density • v2(pt) is seem to not depend on rapidity • p/ show strong  dependency  for given energy depend only on Npar • High-pT suppression increases with energy for given centrality bin  weak dependency on rapidity of RAA which is consistent with surface jet emission  RCP can hide or enhance nuclear effects  At y=3.2 RAA shows larger suppression than RdA

  35. RdAu Update: Identified Particle RdAu at y~3 + blue - red BRAHMS Preliminary • RdAu of identified particle consistent with published h- results • dAu(-)/dAu(+): Valance quark isospin dominates in pp?

  36. Limiting Fragmentation Shift the dNch/d distribution by the beam rapidity, and scale by Npart. Lines up with lower energy  limiting fragmentation Au+Au sNN=200GeV (0-5% and 30-40%) Au+Au sNN=130GeV (0-5%) Pb+Pb sNN=17GeV (9.4%)

  37. Other characteristics versus pbar/p pbar/p controls not only anti-particle to particle ratios but also K/π ratios and K slopes

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