А.Курепин ИЯИ РАН Новые результаты и планы исследований столкновений релятивистских ядер ИТЭФ 24 ноября

Содержание 1.Некоторые результаты по Pb-Pb столкновениям при 2.76 Тэв/c на нуклон ( ALICE, CMS, ATLAS ) 1.Энергетическая зависимость рождения барионов (NA49, NA61, BES ) 2.Возможности измерения столкновения ядер на LHCb с фиксированными мишенями 4. Поиск новых направлений исследования 2

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'Baryon anomaly':  /K 0 4 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 p T compared to RHIC despite large change in underlying spectra ! Ratio at Maximum RHIC  /K 0 x 3

Charged Particle R AA QM2011 J. Schukraft5 PLB 696 (2011) Extrapolated reference => large syst. error 5

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

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

Measure Properties of the Medium Created in Pb+Pb Collisions 1.Collective behavior observed in Pb-Pb collisions at LHC (+0.3 v 2 RHIC ) v 2 (p T ) 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 PRL 105, (2010) [36 citations] Most extreme state of matter ever created in the lab … STAR at RHIC 9

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

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Flow & 2 Particle Correlations 13 Almost any structure can be described with enough coefficients ! - But not if we impose factorization C(p T 1, p T 2)=v(p T 1)*v(p T 2) (or take coefficients from flow analysis). Correlations (|  |>0.8) can be described consistently with 'collective flow' hypothesis for p T < 3-4 GeV ( consistent with 'collectivity ') only partially or not at all for p T > 5 GeV 'away side jet' 2 )  ≈ coefficients from flow analysis coefficients from C(P T 1,P T 2) analysis

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R CP e+e-e+e- J/  suppression: Compared to.. 18 Surprisingly (?) : less suppression than RHIC ! R CP (Alice/Atlas): suppression stronger at high p T ?? Caveats: - J/  (B) ≈  10% (LHCb) => R AA (prompt) lower by ≈ compare to Phenix e + e - ? => less difference, still significant - shadowing(LHC) > shadowing(RHIC) ? => R AA goes up ? - cold nuclear matter suppression ? Very intriguing, nevertheless.. Phenix  R AA ATLAS R CP shadowing range ?

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The Horn Status before

The Horn STAR points from L. Kumar, QM 2011 STAR (BES) results confirm NA49 findings ! 24

The Horn, LHC point LHC point follows the established trend J. Schukraft, QM 2011 LHC point from: 25

The Horn 26 No structure in elementary collisions (too small system for canonical picture) No structure for negative particles (different sensitivity to baryon density) p+p (4π)

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

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. 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

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

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 p T -spectra with HERA and PHENIX form, consistent with COM model, but parameters are energy scaled: dN/dp T ~p T [1+(35  p T /256  ) 2 ] -6 with = 1.4, and using y-spectra as Gaussian with mean value y cm =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 <θ<178 0 ( <θ< ) for generation J/  at z=0 (z=+50 cm).  z=0 I acc = 12.0% z=+50 cm I acc = 8.79% 34

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 p T -spectra with the same parametrization with energy scaled parameter: dN/dp T ~p T [1+(35  p T /256  ) 2 ] -6 where = 1.6, and using y-spectra as Gaussian with mean value y cm =0 and  =1.25.  z=0 I acc = 8.54% z=+50 cm I acc = 5.98% 35

Luminocity, cross sections(x F >0), counting rates System  s  nn  pA =  nn  A 0.92   B  pA L Rate (TeV) (µb) (µb) (%) (µb) (cm -2 s -1 ) (hour -1 ) (TeV) (µb) (µb) (%) (µb) (cm -2 s -1 ) (hour -1 ) pp ∙ pp RHIC ∙ pPb fixed ∙10 29( * ) 168 pPb fixed ∙ pPb NA  10 29( ** ) 535 PbPb fixed ∙10 27 (***) 547 (*) pPb fixed, 500 µ wire, protons/60 min, z=+50 cm (**) pPb NA50, 3  10 7 protons/s, Eur. Phys. J. C33(2004) 31 (***) PbPb cross section, 6.8∙10 8 ions/60 min 36

Выводы 1.На ионном пучке LHC получены новые результаты о взаимодействии ультрарелятивистских ядер, которые существенно дополняют данные, полученные на коллайдере RHIC 2.Однако конкретных указаний на качественно новые эффекты не обнаружено 3.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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Study the onset of deconfinement Onset of Deconfinement: early stage hits transition line, observed signals: kink, horn, step T µBµB energy Kink Horn Step collision energy hadron production properties AGS SPS RHIC 42

Particle production in Pb-Pb: Azimuthal anisotropy x y z Initial spatial anisotropy pypy pxpx Final momentum anisotropy Reaction plane defined by “soft” (low p T ) particles Elliptic flow INTERACTIONS ( hydrodynamics? ) Reaction plane x y z 43

Measure Properties of the Medium Created in Pb+Pb Collisions 1.Collective behavior observed in Pb-Pb collisions at LHC (+0.3 v 2 RHIC ) v 2 (p T ) 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 PRL 105, (2010) [36 citations] Most extreme state of matter ever created in the lab … STAR at RHIC 44

Jet quenching via hadron suppression Phys. Lett. B 696 (2011) [22 citations] Ratio = #(particles observed in AA collision per N-N (binary) collision) #(particles observed per p-p collision) suppression 1.Strong depletion of high-pT hadrons in A-A collisions – parton energy loss (jet quenching) 2. Qualitatively new feature : evolution of R AA as a function of p T 3. New, much anticipated constraint for parton energy-loss models Central collisions Cross-section R AA 1 45

Di-hadron Correlations in PbPb Two-particle correlations - conditional [per-trigger] yields and At Low-p T : Ridge Hydrodynamics, flow At High-p T : Quenching/suppression, broadening Powerful instrument to study system characteristics, including Jet Quenching (recoil jet suppression) Azimuthal Correlation ~ 180 deg Azimuthal Correlation ~ 180 deg Leading particle 46

Модель RELDIS: Relativistic ELectromagnetic DISsociation RELDIS опирается на модель фотоядерных реакций (ИЯИ, , 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 47

Single and mutual EMD with ZDC SINGLE EMD MUTUAL EMD 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 48

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

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Chiral Magnetic Effect ('strong parity violation') 51 B + - Same charge correlations positive Opposite charge correlations negative RHIC ≈ LHC somewhat unexpected should decrease with N ch may decrease with √s. ? + - B ? RHIC Local Parity Violation in strong magnetic Field ?

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