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А.КурепинИЯИ РАН
Новые результаты и планы исследованийстолкновений релятивистских ядер
ИТЭФ 24 ноября 2011 1
Содержание
1. Некоторые результаты по Pb-Pb столкновениям при 2.76 Тэв/c на нуклон ( ALICE, CMS, ATLAS )2. Энергетическая зависимость рождения барионов
(NA49, NA61, BES )3. Возможности измерения столкновения ядер на LHCb с фиксированными мишенями4. Поиск новых направлений исследования
2
33
'Baryon anomaly': L/K0
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 pT compared to RHIC despite large change in underlying spectra !
Ratio at MaximumRHICL/K0
x 3
Charged Particle RAA
QM2011 J. Schukraft 5
PLB 696 (2011) 30-39
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 RAA as a function of
pT
3. New, much anticipated constraint for parton energy-loss models
Centralcollisions
Cross-section
RAA
1
6
77
Particle production in Pb-Pb:Azimuthal anisotropy
xy z
Initial spatial anisotropy
py
px
Final momentum anisotropy22
22
xy
xy
22
22
2yx
yx
pp
ppv
Reaction plane defined by “soft” (low pT) particles
Elliptic flow
INTERACTIONS( hydrodynamics? )
Reaction plane
xy z
Reaction plane
8
Measure Properties of the Medium Created in Pb+Pb
Collisions
1. 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 flow3. Additional constraints on Eq-Of-State and transport properties
PRL 105, 252302 (2010) [36 citations]
Most extreme state of matter ever created in the lab …
STAR at RHIC
9
• 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 fluctuations s (influence measured v2, depending on method)– measure non-flow correlations d (eg jets)– improve theory precision (3D hydro, 'hadronic afterburner', ...)– .........
CERN, 2 Dec 2010 J. Schukraft
10 Azimuthal Flow: What next ?
sh mkT2
STAR at RHIC
PRL 105, 252302 (2010)
22
22
}4{
}2{
nnn
nnn
vv
vv
s
ds
10
1111
1212
Flow & 2 Particle Correlations
13
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
'away side jet'
2 ) P
≈ coefficients from flow analysis
coefficients from C(PT1,PT2) analysis
14
1515
16
17
RCP
e+e-
J/Y suppression: Compared to..
18
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) ? => RAA goes up ?- cold nuclear matter suppression ?
Very intriguing, nevertheless ..
Phenix mm
RAA
ATLAS
RCP
shadowing range
?
1919
20
21
22
The HornStatus before 2010
23
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 2011LHC 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 StepreReduction of transverse expansion
1m
dNdm
constem tT
28
29
30
31
.
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 2009.32
.
Colliders (RHIC,LHC)
New Opportunities Workshop….. CERN – 13 May 2009.
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 = 114.6 GeV (5000 GeV, √s = 96.9 GeV)pA collisions
AA collisionsRHIC CuCu, AuAu √s =130 GeV, 200 GeVLHC PbPb √s = 5.5 TeV
pA collisionsRHIC pp, dAu √s =130 GeV, 200 GeVLHC pp, pA √s = 14 (10) TeV
Fixed-target data (SPS, FNAL, HERA)
AA collisionsSU, PbPb, InIn
SPS: NA38, NA50, NA60√s(GeV) 19.4 17.3
pA collisions HERA-B, E866, NA50/51, NA38/3, NA60 √s(GeV) 41.6 38.8 29.1/27.4 19.4 27.4/17.3
33
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+(35ppT/256 <pT>)2]-6 with <pT>= 1.4, and using y-spectra as Gaussian with mean value ycm=0 and s=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%
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 pT-spectra with the same parametrization with energy scaled parameter: dN/dpT~pT[1+(35p pT/256 <pT>)2]-6 where <pT>= 1.6, and using y-spectra as Gaussian with mean value ycm=0 and s=1.25.
z=0
Iacc = 8.54%
z=+50 cm
Iacc = 5.98%
35
Luminocity, cross sections(xF>0) , counting rates
System s snn spA=snnA0.92 BspA L Rate (TeV) (µb) (µb) (%) (µb) (cm-2s-1) (hour-1)
pp 14 32.9 32.9 4.7 0.091 3∙1030 982ppRHIC 0.200 2.7 2.7 3.59 0.0057 2∙1031 410pPbfixed 0.1146 0.65 88.2 5.98 0.310 1.5∙1029(*) 168pPbfixed 0.0718 0.55 74.6 7.97 0.349 1.5∙1029 189pPbNA50 0.0274 0.19 25.8 14.0 0.212 71029(**) 535PbPbfixed 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, 3107 protons/s, Eur. Phys. J. C33(2004) 31(***) PbPb cross section, 6.8∙108 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
3737
38
3939
4040
4141
Study the onset of deconfinement
Onset of Deconfinement:early stage hits transition line,
observed signals: kink, horn, stepT
µB
energy
Kink
Horn
Step
collision energy
hadr
on p
rodu
ctio
n pr
oper
ties
AGS SPS RHIC
42
Particle production in Pb-Pb:Azimuthal anisotropy
xy z
Initial spatial anisotropy
py
px
Final momentum anisotropy22
22
xy
xy
22
22
2yx
yx
pp
ppv
Reaction plane defined by “soft” (low pT) particles
Elliptic flow
INTERACTIONS( hydrodynamics? )
Reaction plane
xy z
Reaction plane
43
Measure Properties of the Medium Created in Pb+Pb
Collisions
1. 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 flow3. Additional constraints on Eq-Of-State and transport properties
PRL 105, 252302 (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 RAA as a function of
pT
3. New, much anticipated constraint for parton energy-loss models
Centralcollisions
Cross-section
RAA
1
45
Di-hadron Correlations in PbPb
Two-particle correlations - conditional [per-trigger] yields and
At Low-pT :
RidgeHydrodynamics, flowAt High-pT :
Quenching/suppression, broadeningPowerful instrument to study system characteristics, including Jet Quenching (recoil jet suppression)
AzimuthalCorrelation~ 180 deg
Leading particle
46
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
47
Single and mutual EMD with ZDC
SINGLE EMD MUTUAL EMD
ZDC signal: Single EMD + Mutual EMD + Nuclear effectsMutual EMD event selection: ZNC && ZNA + ZDC time selection + (ZEM1<10 || ZEM2<10) estimated from simulations to reject nuclear eventsData: 1n peak resolution consistent with RELDIS calculationRatios: 1n/2n; 1n/3n; 2n/3n are under investigation
1n1380 GeV
2n
48
The Dale
s y2 (hydro) = 8
3cs
2
1- cs4
lnsNN
2mN
, with cs
2 13
Reduction of longitudinal expansion
Petersen, Bleicher, nucl-th/0611001v1
s y2 (p - ) = 8
3cs
2
1- cs4
lnsNN
2mN
No new points from STAR and ALICE (PID at mid–rapidity only)
4949
50
Chiral Magnetic Effect ('strong parity violation')
51
RPY 2cos
B+-
Same charge correlations positiveOpposite charge correlations negativeRHIC ≈ LHCsomewhat unexpected
should decrease with Nch
may decrease with √s
.?
cos
+ -
B
?
RHIC
RHIC
Local Parity Violation in strong magnetic Field ?
52
53
54