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А.Курепин ИЯИ РАН

Новые результаты и планы исследований столкновений релятивистских ядер. А.Курепин ИЯИ РАН. ИТЭФ 2 4 ноября 2011. Содержание. Некоторые результаты по Pb-Pb столкновениям при 2.76 Тэв /c на нуклон ( ALICE, CMS, ATLAS )

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А.Курепин ИЯИ РАН

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  1. Новые результаты и планы исследований столкновений релятивистских ядер А.Курепин ИЯИ РАН ИТЭФ24 ноября 2011

  2. Содержание • Некоторые результаты по Pb-Pb столкновениям при 2.76 Тэв/c на нуклон ( ALICE, CMS, ATLAS ) • Энергетическая зависимость рождения барионов (NA49, NA61, BES ) • Возможности измерения столкновения ядер на LHCb с фиксированными мишенями 4. Поиск новых направлений исследования

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  4. 'Baryon anomaly': L/K0 x 3 RHIC L/K0 Ratio at Maximum Baryon/Meson ratio still strongly enhanced x 3 compared to pp at 3 GeV - Enhancement slightly larger than at RHIC 200 GeV - Maximum shift very little in pT compared to RHIC despite large change in underlying spectra !

  5. Charged Particle RAA PLB 696 (2011) 30-39 Extrapolated reference => large syst. error QM2011 J. Schukraft 5

  6. Jet quenching via hadron suppression #(particles observed in AA collision per N-N (binary) collision) #(particles observed per p-p collision) Ratio = Phys. Lett. B 696 (2011) [22 citations] Cross-section 1 Central collisions RAA suppression • Strong depletion of high-pT hadrons in A-A collisions • – parton energy loss (jet quenching) • 2. Qualitatively new feature : evolution of RAA as a function of pT • 3. New, much anticipated constraint for parton energy-loss models

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  8. Particle production in Pb-Pb:Azimuthal anisotropy z z y y x x py Reaction plane Reaction plane px INTERACTIONS ( hydrodynamics? ) Final momentum anisotropy Reaction plane defined by “soft” (low pT) particles Initial spatial anisotropy Elliptic flow

  9. Measure Properties of the Medium Created in Pb+Pb Collisions Most extreme state of matter ever created in the lab … PRL 105, 252302 (2010) [36 citations] STAR at RHIC • Collective behavior observed in Pb-Pb collisions at LHC (+0.3 v2RHIC) • v2(pT) similar to RHIC – almost ideal fluid at LHC ? • 2. New input to the energy dependence of collective flow • 3. Additional constraints on Eq-Of-State and transport properties

  10. Precision measurement of h/s: current RHIC limit: h/S < (2-5) x 1/4p h/S < 1/4p => conjectured AdS/CFT limit is wrong h/S > 1/4p => measure s h/S ≈ 1/4p => quantum corrections which are O(10-30%) in AdS/CFT! 20% in v2 ~ 1/4p => need few % precision Precision: How ? fix initial conditions (geometrical shape is model dependent, eg Glauber, CGC) quantify flow fluctuationss (influence measured v2, depending on method) measure non-flow correlationsd (eg jets) improve theory precision (3D hydro, 'hadronic afterburner', ...) ......... 10 Azimuthal Flow: What next ? STAR at RHIC PRL 105, 252302 (2010) CERN, 2 Dec 2010 J. Schukraft

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  13. Flow & 2 Particle Correlations ≈ coefficients from flow analysis 'away side jet' coefficients from C(PT1,PT2) analysis Almost any structure can be described with enough coefficients ! - But not if we impose factorization C(pT1, pT2)=v(pT1)*v(pT2)(or take coefficients from flow analysis). Correlations (|h|>0.8) can be described consistently with 'collective flow' hypothesis for pT < 3-4 GeV ( consistent with 'collectivity ') only partially or not at all for pT > 5 GeV 2 )P

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  16. ? J/Y suppression: Compared to.. RCP e+e- RAA Phenix mm ATLAS RCP Surprisingly (?) : less suppression than RHIC ! RCP(Alice/Atlas): suppression stronger at high pT ?? Caveats: -J/Y (B) ≈10% (LHCb) => RAA(prompt) lower by ≈ 0.05 - compare to Phenix e+e- ? => less difference, still significant - shadowing(LHC) > shadowing(RHIC) ? => RAAgoes up ? - cold nuclear matter suppression ? shadowing range Very intriguing, nevertheless ..

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  18. The Horn Status before 2010

  19. The Horn STAR points from L. Kumar, QM 2011 STAR (BES) results confirm NA49 findings !

  20. The Horn, LHC point LHC point from: J. Schukraft, QM 2011 LHC point follows the established trend

  21. The Horn p+p (4π) No structure in elementary collisions (too small system for canonical picture) No structure for negative particles (different sensitivity to baryon density)

  22. The Step re Reduction of transverse expansion • similar structure seems to develop • step-like pattern is confirmed • step-like pattern is confirmed • no structure in elementary reactions

  23. . Fixed target charmonium production with proton and lead beams at LHC A.B.Kurepin, N.S.Topilskaya, M.B.Golubeva INR RAS, Moscow 1. Physics motivation. 2. Geometrical acceptances for J/ measurement at ALICE for PbPb interactions at s= 5.5 TeV and pp interaction at s = 14 TeV. 3. Evaluation of geometrical acceptances for PbPb and p-A fixed target J/ measurement by dimuon spectrometer of ALICE. 5. Luminosity and counting rate estimation. 6. Conclusions. New Opportunities Workshop…..N.S.Topilskaya, CERN – 13 May 2009.

  24. . Fixed-target data (SPS, FNAL, HERA) AA collisions SU, PbPb, InIn SPS: NA38, NA50, NA60 √s(GeV) 19.4 17.3 HERA-B, E866, NA50/51, NA38/3, NA60 √s(GeV) 41.6 38.8 29.1/27.4 19.4 27.4/17.3 pA collisions Colliders (RHIC,LHC) RHIC CuCu, AuAu √s =130 GeV, 200 GeV LHC PbPb √s = 5.5 TeV AA collisions RHIC pp, dAu √s =130 GeV, 200 GeV LHC pp, pA √s = 14 (10) TeV pA collisions Fixed-target (LHC) – new opportunity – energy between SPS and RHIC Pb-Pb 2750 GeV/nucleon, √s = 71.8 GeV AA collisions p-A 7000 GeV , √s = 114.6 GeV (5000 GeV, √s = 96.9 GeV) pA collisions New Opportunities Workshop….. CERN – 13 May 2009.

  25. Fixed target experiment Pb-Pb, T=2750 GeV, s=71.8 GeV. J/ are generated at z=0 and outside of ITS at z=+50 cm. J/ are generated using pT-spectra with HERA and PHENIX form, consistent with COM model, but parameters are energy scaled: dN/dpT~pT[1+(35pT/256  <pT>)2]-6 with <pT>= 1.4, and using y-spectra as Gaussian with mean value ycm=0 and =1.1 J/ are accepted in the rapidity range -2.5<η<-4.0(-2.98<η<-4.14), and each of 2 muons in the degree range 1710 <θ<1780(174.20 <θ< 178.20) for generation J/ at z=0 (z=+50 cm).  z=0 Iacc = 12.0% z=+50 cm Iacc = 8.79%

  26. Fixed target experiment pA, T=7000 GeV, s=114.6 GeV. J/ are generated at z=0 and outside ITS at z=+50 cm. J/ are generated using pT-spectra with the same parametrization with energy scaled parameter: dN/dpT~pT[1+(35 pT/256 <pT>)2]-6 where <pT>= 1.6, and using y-spectra as Gaussian with mean value ycm=0 and =1.25.  z=0 Iacc = 8.54% z=+50 cm Iacc = 5.98%

  27. Luminocity, cross sections(xF>0) , counting rates System s nn pA=nnA0.92  BpA L Rate (TeV) (µb) (µb) (%) (µb) (cm-2s-1) (hour-1) pp 14 32.9 32.9 4.7 0.091 3∙1030 982 ppRHIC 0.200 2.7 2.7 3.59 0.0057 2∙1031 410 pPbfixed 0.1146 0.65 88.2 5.98 0.310 1.5∙1029(*) 168 pPbfixed 0.0718 0.55 74.6 7.97 0.349 1.5∙1029 189 pPbNA50 0.0274 0.19 25.8 14.0 0.212 71029(**) 535 PbPbfixed 0.0718 0.55 10130 7.97 47.5 3.2∙1027(***) 547 (*) pPbfixed, 500 µ wire, 1012 protons/60 min, z=+50 cm (**) pPbNA50, 3107 protons/s, Eur. Phys. J. C33(2004) 31 (***)PbPb cross section, 6.8∙108 ions/60 min

  28. Выводы • На ионном пучке LHC получены новые результаты о взаимодействии • ультрарелятивистских ядер, которые существенно дополняют данные , • полученные на коллайдере RHIC • Однако конкретных указаний на качественноновые эффекты не • обнаружено • Необходимо искать новые пути исследования: • эксперименты при более низких энергиях • расширение набора сталкивающихся ядер , • которые вполне достижимы в ближайшее время 37

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  32. Study the onset of deconfinement AGS SPSRHIC Onset of Deconfinement: early stage hits transition line, observed signals: kink, horn, step Kink T Horn hadron production properties energy Step µB collision energy

  33. Particle production in Pb-Pb:Azimuthal anisotropy z z y y x x py Reaction plane Reaction plane px INTERACTIONS ( hydrodynamics? ) Final momentum anisotropy Reaction plane defined by “soft” (low pT) particles Initial spatial anisotropy Elliptic flow

  34. Measure Properties of the Medium Created in Pb+Pb Collisions Most extreme state of matter ever created in the lab … PRL 105, 252302 (2010) [36 citations] STAR at RHIC • Collective behavior observed in Pb-Pb collisions at LHC (+0.3 v2RHIC) • v2(pT) similar to RHIC – almost ideal fluid at LHC ? • 2. New input to the energy dependence of collective flow • 3. Additional constraints on Eq-Of-State and transport properties

  35. Jet quenching via hadron suppression #(particles observed in AA collision per N-N (binary) collision) #(particles observed per p-p collision) Ratio = Phys. Lett. B 696 (2011) [22 citations] Cross-section 1 Central collisions RAA suppression • Strong depletion of high-pT hadrons in A-A collisions • – parton energy loss (jet quenching) • 2. Qualitatively new feature : evolution of RAA as a function of pT • 3. New, much anticipated constraint for parton energy-loss models

  36. Di-hadron Correlations in PbPb Two-particle correlations - conditional [per-trigger] yields Leading particle and • At Low-pT: • Ridge • Hydrodynamics, flow • At High-pT: • Quenching/suppression, broadening • Powerful instrument to study system characteristics, including Jet Quenching (recoil jet suppression) Azimuthal Correlation ~ 180 deg

  37. Модель RELDIS: Relativistic ELectromagnetic DISsociation • RELDIS опирается на модель фотоядерных реакций (ИЯИ, 1995-2008, А.С.Ильинов, И.А.Пшеничнов) • Поглощение фотонов ядрами – многостадийный процесс: • поглощение фотона на внутриядерном нуклоне или на квазидейтонной паре (учитывается свыше 100 каналов при энергиях фотонов несколько ГэВ) • внутриядерный каскад образовавшихся адронов • статистический распад возбужденного остаточного ядра – модель SMM: конкуренция испарения нуклонов и кластеров - деление - мультифрагментация

  38. Single and mutual EMD with ZDC ZDC signal: Single EMD + Mutual EMD + Nuclear effects Mutual EMD event selection: ZNC && ZNA + ZDC time selection + (ZEM1<10 || ZEM2<10) estimated from simulations to reject nuclear events Data: 1n peak resolution consistent with RELDIS calculation Ratios: 1n/2n; 1n/3n; 2n/3n are under investigation 1n 1380 GeV 2n SINGLE EMD MUTUAL EMD

  39. The Dale Reduction of longitudinal expansion Petersen, Bleicher, nucl-th/0611001v1 No new points from STAR and ALICE (PID at mid–rapidity only) 49

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