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High P T phenomena in h-A and A-A collisions at fixed-target energies

High P T phenomena in h-A and A-A collisions at fixed-target energies. Pre-HI high energy nuclear physics Cronin (alias initial state) effect Early R AA and R CP results from SPS exp. New (QM05) R CP data of NA57 and NA49 NA57/WA97 preliminary results on R AA

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High P T phenomena in h-A and A-A collisions at fixed-target energies

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  1. High PT phenomena in h-A and A-A collisions at fixed-target energies • Pre-HI high energy nuclear physics • Cronin (alias initial state) effect • EarlyRAA and RCP results from SPS exp. • New (QM05) RCP data of NA57 and NA49 • NA57/WA97 preliminary results on RAA • AA di-hadron Φ correlations (from NA45) • Summary and conclusions OUTLINE

  2. High energy nuclear physics of the70’s – 80’s • Excited nucleon states in nuclei + hypernuclei • Interactions of shortly living states (in statu nascendi) with nucleons • Particle multiplication processes: multiplicities • Modification of PDF in nuclei (EMC effect) • Mass number (A) dependence of the (inclusive) cross sections:

  3. CERN- THE SECOND 25 YEARS Physics Reports, vol. 403-404, December 2004 >1976 – SPS, 400 GeV/c p primary beam The production of jets in hard parton-parton scattering was not really studied at the SPS since, at these energies, the jet structure could not be well resolved from the dominant background of soft processes; this was also the case for the prompt production of mesons at high Pt expected to proceed via higher twist QCD mechanism and to have a cleaner experimental signature than that of jets (WA77)  No dedicated experiments on high Pt hadron production (at SPS)

  4. CERN WA72 nuclear experiment 30GeV/c M. G. Abreu et al. CERN/EP 84-51, April 1984 D.S. Barton et al. PRD 27 (1983) 2580 general trend p data do not fit to Aα

  5. Fermilab high Pt nuclear experiment D. Antreasyan, J. W. Cronin et al, Phys. Rev. D19 (1979) 764-778 p beam 200,300,400 GeV/c, θcms≈ 0, targets: p, d, Be, Ti, W Pt = 0.77 – 6.9 GeV/c, particles: π, K, p and antiprotons Cronin effect

  6. fit without D fit with D Aα extrapolation down to pp ? pp cross section lies below σ0

  7. Cronin: relation between α - RAA 185mb 1.66b When: α=1, <Ncoll(Pb)>=3.75, <Ncoll(Be)>=1.50 (Glauber) R(Pb,Be) = …1.03 ! not too bad

  8. Cronin: α RpA for K+ at 200 GeV/c (Only 3 points at 200 GeV/c , more at 400 GeV/c)

  9. Antreasyan et.al.Phys.Rev.D19(3)1979 PRELIMINARY Cronin: RHIC – Fermilab comparison qualitative agreement p+A sqrt(s)=27.4 GeV

  10. Cronin effect - initial state Kt broadening Ex: Saturating Cronin effect in ultra-relativistic proton-nucleus collisions, G. Papp, P. Lévai and G. Fai, nucl-th/9903012 Data of Antreasyan et al In conclusions: We are confident that complete NLO calculations, which are left for future work, will improve the agreement further

  11. HEAVY IONS at CERN SPS AFTER 1986 Priority to the sensitive probes of QGP (strangeness, J/Ψ etc) + bulk properties: multiplicities, Y- Pt spectra (blast wave), flow…

  12. Where is the jet quenching in Pb-Pb ? Xin-Nian Wang , hep-ph/9804384,1998 NO EVIDENCE !?

  13. Reaction operator approach Gyulassy, Levai, Vitev, NP B 594(2001) 371 factor ~ 4

  14. Discovery ! At RHIC ! (2 years after discovery of QGP at CERN  1:1) J. D. Bjorken Fermilab-Pub-82-059-THY

  15. 1-6% 22-43% HIJING RCP WA98 data mT - m0 (GeV) Central-to-peripheral nuclear modification factor(s) • RCP at RHIC: • high-pT: parton energy loss • intermediate pT: baryon/meson effect (recombination?) • RCP at SPS? • p0 suppressed: energy loss? (see also RAA re-analysis) • no baryon/meson comparison WA98, EPJC23 (2002) 225 d’Enterria, PLB596 (2004) 32 STAR, PRL92 (2004) 052302 + prelim.

  16. Vitev and Gyulassy PRL 89, 252301 (2002) WA98, Eur.Phys. J. C23, 225 (2002) RCP RAA ? RAA(central) mT-m0(GeV/c2) The (old) SPS RAA/RCP puzzle See also: X. N. Wang, Phys. Rev. C61, 064910(2000) • WA98 p0: RAA enhanced, RCP suppressed for central Pb+Pb • Calculations: with Cronin effect + quenching do not describe data

  17. SPS Heavy Ion Data Revisited, but a problem: At the SPS (√s = 20 GeV) no good p+p->π0/h reference… D. d’Enterria, nucl-ex/0403055 nucl-ex/0504001 Vitev-Gyulassy Energy loss with dNglue/dy = 400-600* * Compared to dNglue/dy = 200-300 in PRL 89 252301 (2002)

  18. Anti Shadowing Shadowing D'Enterria '05 Excitation function of the nuclear modification factor Fixed pt SPS Cronin effect + nuclear (anti)shadowing ~compensated by parton energy loss at SPS !

  19. NA57 RCP results

  20. Centrality (in)dependence of correction weights  no need of MC corrections • Corrections for acceptance and efficiency calculated by embedding MC particles of given pT and y in real events, at the level of hits 1.0 no centrality dependence

  21. RCP from NA57 : PL-B623(2005)17-25 π,K,p cocktail Centrality dependence

  22. PHENIX RCP Au-Au 200 GeV p p p K0 vs π0 comparison SPS RHIC Strangeness matters (not only number of valence quarks)

  23. Strange meson vs strange baryon SPS vs RHIC Similar hierarchy but (of course) a shift by about 0.5 units meson/baron compatible with the parton coalescence mechanism

  24. Comparison with the parton energy loss models Evidence for parton energy loss at SPS energy

  25. from 200 to 17 GeV PQM Energy evolution: PQM vs NA57 data Wang and PQM both consistent with NA57 (factor 2 suppression)

  26. NA49 talk by A. Lazslo Qualitative agreement with NA57 (different peripheral classes !) NA49 new data at QM05 • RCP(baryon)>RCP(meson) • same systematics as original Cronin data at similar s • same systematics as RHIC but scaled upward

  27. Backward reconstruction of RAA (NA57) • p-Be data (at 158 GeV/c) only from WA97 • Pb-Pb V0 ‘s available both from WA97 and NA57  1998 (NA57) data used only (stat. errors dominated by p-Be anyway) • A simple (toy) MC  main pt dependent correction factors (like acceptance and kinematical cuts) taken into account ! • Normalization based on measured (from fully corrected sub-samples), Pt truncated yields • Pt corrections applied bin by bin

  28. Correction factors for Pt cut 0.5 GeV/c Full centrality

  29. TOY-MC Pt WEIGHTS (+ geometrical & kinematical cuts) Fits to guide the eye Pt > 0.5 GeV/c WA97 and NA57 - similar telescopes but geometries slightly different Pt

  30. NA57 RAA - very preliminary Consistent with measured Strangeness Enhancement (as function of Ncoll) Pt > 0.5 GeV/c

  31. Enhancement = <Yield> / <Nbin> 10 10 (<Yield> / <Nbin>)p-Be <Nbin> 1 1 Enhancements w.r.t. number of binary collisions at 158 A GeV/c • Going from p-Be to Pb-Pb X and W yields scale • faster than <Nbin>

  32. AA di-hadron Φ correlations at SPS width yield • RHIC: disappearance of the away-side jet in central collisions • SPS? PRL92(2004)032301 • qualitatively: similar pattern • quantitatively, within these errors: • consistent with acoplanarity broadening • no evidence for suppression of away-side yield NA45peripheral NA45central

  33. SUMMARY & CONCLUSIONS • High energy nuclear physics (before HI’s) legacy • Cronin effect discovered at Fermilab (missed at SPS) • Early SPS high Pt (HI) data, new analysis after discovery of jet quenching at RHIC • WA80, WA98, NA45, NA49 and NA57 high Pt data point to the non-negligible parton energy loss in the final state, already at sqrt(s) = 17.3 GeV/c • Consistency with the Theory – scaling with dNg/dy • SPS quenching data, in principle, less biased by the corona effect than RHIC (and LHC) data, but Pt range quite limited ( jet tomography not accessible)

  34. The NA57 Collaboration F. Antinorik,P.A. Bacone,A. Badalàf, R. Barberaf,A. Belogiannia,I.J. Bloodworthe,M. Bombarah,G.E. Brunob,S.A. Bulle,R. Caliandrob,M. Campbellg, W. Carenag, N. Carrerg,R.F. Clarkee,A. Dainesek,D. Di Barib,S. Di Liberton,R. Diviàg,D. Eliab,D. Evanse,G.A. Feofilovp,R.A. Finib,P. Ganotia,B. Ghidinib,G. Grellao,H. Helstrupd, K.F. Hetlandd,A.K. Holmej,A. Jacholkowskif, G.T. Jonese, P. Jovanovice, A. Juskoe,R. Kamermansr,J.B. Kinsone,K. Knudsong,V. Kondratievp,I. Králikh,A. Kravčákovái,P. Kuijerr,V. Lentib,R. Lietavae,G. Løvhøidenj,V. Manzarib,M.A. Mazzonin,F. Meddin,A. Michalonq,M. Morandok,P.I. Normane,A. Palmerif, G.S. Pappalardof,B. Pastirčákh,R.J. Platte,E. Quercighk,F. Riggif,D. Röhrichc,G. Romanoo,K. Šafaříkg,L. Šándorh,E. Schillingsr,G. Segatok,M. Senél, R. Senél,W. Snoeysg, F. Soramelk,M. Spyropoulou-Stassinakia,P. Starobam,R. Turrisik,T.S. Tveterj,J. Urbáni,P. van de Venr,P. Vande Vyvreg, A. Vascottog,T. Vikj,O. Villalobos Bailliee,L. Vinogradovp,T. Virgilio,M.F. Votrubae,J. Vrlakovai,P. Závadam. a: Athens, b: Bari,c: Bergen,d: Bergen,e: Birmingham,f: Catania,g: CERN,h: Kosice,i: Kosice,j: Oslo,k: Padova,l: Collège de France,m: Prague, n: Rome,o: Salerno,p: St. Petersburg,q: Strasbourg,r: Utrecht

  35. backup slides (just in case…)

  36. WA77 CERN higher twist experiment π-Be 150,300 GeV/c …nothing in our data contradicts the HT estimates following from QCD sum rules predictions. A Belogianni et al., Z. Phys. C 69 (1996)235

  37. d2N(h-)/dpTdy (d+Au) RdAu = NColld2N(-)/dpTdy (p+p) Experimental facts – dAu (pPb) at SPS T. Alber et al. (NA35), Eur. Phys. J. C 2, 643 (1998) B. Boimska (NA49), PhD thesis, Warszawa (2004) dAu pPb Similar trend at the AGS: R. Debbe et al. (BRAHMS) CINPP proceedings (2005) • Increasing suppression with increasing xF • Pattern similar for pions and antiprotons, different for protons

  38. NA57 Experimental Layout Target: 1% Pb Scintillator Petals: centrality trigger MSD: Multiplicity Silicon Detector Tracking device: silicon pixel planes (5 x 5 cm2 ) Lever arm: double-sided mstrips

  39. NA57 acceptance

  40. L X- W- L X+ W+ NA57 mass signals

  41. Pb-Pb 160 A GeV 0 1 2 3 4 NA57 centrality bins

  42. + modified recombination

  43. CBBO - CERN BIG BANG ORCHESTRA Acceleration/ Celebration

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