“trends in heavy ion physics research” dubna may 22-24, 2008
DESCRIPTION
Hot and dense matter: from RHIC to LHC. “Trends in heavy ion physics research” Dubna May 22-24, 2008. Itzhak Tserruya. Hot and dense matter: from RHIC to RHIC and LHC. “Trends in heavy ion physics research” Dubna May 22-24, 2008. Itzhak Tserruya. Outline. Introduction - PowerPoint PPT PresentationTRANSCRIPT
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008 11
““Trends in heavy ion physics research”Trends in heavy ion physics research” Dubna May 22-24, 2008 Dubna May 22-24, 2008
Itzhak TserruyaItzhak Tserruya
Hot and dense matter:Hot and dense matter:from RHIC to LHC from RHIC to LHC
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008 22
““Trends in heavy ion physics research”Trends in heavy ion physics research” Dubna May 22-24, 2008 Dubna May 22-24, 2008
Itzhak TserruyaItzhak Tserruya
Hot and dense matter:Hot and dense matter:from RHIC to RHIC and LHC from RHIC to RHIC and LHC
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008 33
OutlineOutline
Introduction
Highlights from RHIC Flow Charmonium Low-mass dileptons Thermal radiation High pT suppression
Summary
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008 44
IntroductionIntroduction
Eight years of RHIC operationEight years of RHIC operationRHIC’s main goalsRHIC’s main goals– Nuclear collisionsNuclear collisions
To provide definitive experimental evidence for/against To provide definitive experimental evidence for/against Quark Gluon Plasma (QGP)Quark Gluon Plasma (QGP)
and study its properties under the much better conditions offered by RHICand study its properties under the much better conditions offered by RHIC
LargeLarge √s √s Access to reliable pQCD probes Access to reliable pQCD probes
– Polarized p+p collisionsPolarized p+p collisions
Accelerator complexAccelerator complex– Impressive machine performance:Impressive machine performance:
Routine operation at 2-4 x design luminosity (Au+Au)Routine operation at 2-4 x design luminosity (Au+Au)
– Extraordinary variety of operational modesExtraordinary variety of operational modesCollided four different species: Au+Au, d+Au, Cu+Cu, pCollided four different species: Au+Au, d+Au, Cu+Cu, p+p+p4 Energies: 20 GeV (Au+Au, Cu+Cu), 62 GeV (Au+Au,Cu+Cu, p4 Energies: 20 GeV (Au+Au, Cu+Cu), 62 GeV (Au+Au,Cu+Cu, p+p+p) , ) ,
130 GeV (Au+Au), 200 GeV (Au+Au, Cu+Cu, d+Au, p130 GeV (Au+Au), 200 GeV (Au+Au, Cu+Cu, d+Au, p+p+p))
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PHENIX Run HistoryPHENIX Run HistoryYear Species √s [GeV ] ∫Ldt Ntot (sampled) Data Size
Run1 2000 Au - Au 130 1 µb-1 10 M 3 TB
Run2 2001/02 Au - Au 200 24 µb-1 170 M 10 TB
Au - Au 19 < 1 M
p - p 200 0.15 pb-1 3.7 B 20 TB
Run3 2002/03 d - Au 200 2.74 nb-1 5.5 B 46 TB
p - p 200 0.35 pb-1 6.6 B 35 TB
Run4 2003/04 Au - Au 200 241 µb-1 1.5 B 270 TB
Au - Au 62.4 9 µb-1 58 M 10 TB
Run5 2005 Cu - Cu 200 3 nb-1 8.6 B 173 TB
Cu - Cu 62.4 0.19 nb-1 0.4 B 48 TB
Cu - Cu 22.4 2.7 µb-1 9 M 1 TB
p - p 200 3.8 pb-1 85 B 262 TB
Run-6 2006 p - p 200 10.7 pb-1 233 B 310 TB
p - p 62.4 0.1 pb-1 10 B 25 TB
Run-7 2007 Au - Au 200 725 µb-1 4.6 B 570 TB
Run-8 2007/08 d - Au 200
p - p 200/500
Itzhak TserruyaItzhak Tserruya 66JINR, May 22, 2008JINR, May 22, 2008
Itzhak TserruyaItzhak Tserruya
Eight years of RHIC operationEight years of RHIC operationRHIC’s main goalsRHIC’s main goals– Nuclear collisionsNuclear collisions
To provide definitive experimental evidence for/against To provide definitive experimental evidence for/against Quark Gluon Plasma (QGP)Quark Gluon Plasma (QGP)
and study its properties under the much better conditions offered by RHICand study its properties under the much better conditions offered by RHIC
LargeLarge √s √s Access to reliable pQCD probes Access to reliable pQCD probes
– Polarized p+p collisionsPolarized p+p collisions
Accelerator complexAccelerator complex– Impressive machine performance:Impressive machine performance:
Routine operation at 2-4 x design luminosity (Au+Au)Routine operation at 2-4 x design luminosity (Au+Au)
– Extraordinary variety of operational modesExtraordinary variety of operational modesCollided four different species: Au+Au, d+Au, Cu+Cu, pCollided four different species: Au+Au, d+Au, Cu+Cu, p+p+p4 Energies: 20 GeV (Au+Au, Cu+Cu), 62 GeV (Au+Au,Cu+Cu, p4 Energies: 20 GeV (Au+Au, Cu+Cu), 62 GeV (Au+Au,Cu+Cu, p+p+p) , ) ,
130 GeV (Au+Au), 200 GeV (Au+Au, Cu+Cu, d+Au, p130 GeV (Au+Au), 200 GeV (Au+Au, Cu+Cu, d+Au, p+p+p))
Two small detectors, two large detectors Two small detectors, two large detectors – Complementary capabilities. Worked !Complementary capabilities. Worked !
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Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008
RHIC and Its ExperimentsRHIC and Its Experiments
STARSTAR
88
Eight years of RHIC operationEight years of RHIC operationRHIC’s main goalsRHIC’s main goals– Nuclear collisionsNuclear collisions
To provide definitive experimental evidence for/against To provide definitive experimental evidence for/against Quark Gluon Plasma (QGP)Quark Gluon Plasma (QGP)
and study its properties under the much better conditions offered by RHICand study its properties under the much better conditions offered by RHIC
LargeLarge √s √s Access to reliable pQCD probes Access to reliable pQCD probes
– Polarized p+p collisionsPolarized p+p collisions
Accelerator complexAccelerator complex– Impressive machine performance:Impressive machine performance:
Routine operation at 2-4 x design luminosity (Au+Au)Routine operation at 2-4 x design luminosity (Au+Au)
– Extraordinary variety of operational modesExtraordinary variety of operational modesCollided four different species: Au+Au, d+Au, Cu+Cu, pCollided four different species: Au+Au, d+Au, Cu+Cu, p+p+p4 Energies: 20 GeV (Au+Au, Cu+Cu), 62 GeV (Au+Au,Cu+Cu, p4 Energies: 20 GeV (Au+Au, Cu+Cu), 62 GeV (Au+Au,Cu+Cu, p+p+p) , ) ,
130 GeV (Au+Au), 200 GeV (Au+Au, Cu+Cu, d+Au, p130 GeV (Au+Au), 200 GeV (Au+Au, Cu+Cu, d+Au, p+p+p))
Two small detectors, two large detectors Two small detectors, two large detectors – Complementary capabilities. Worked !Complementary capabilities. Worked !
ScienceScience– Unexpected results, major discoveriesUnexpected results, major discoveries– More than 170 papers in refereed literature, among them ~100 PRLMore than 170 papers in refereed literature, among them ~100 PRL
Future: RHIC and LHCFuture: RHIC and LHC– Key science questions identifiedKey science questions identified– Accelerator and experiment upgrade program underway to perform that scienceAccelerator and experiment upgrade program underway to perform that science– LHC to open a new energy frontier (increase by a factor of ~30!)LHC to open a new energy frontier (increase by a factor of ~30!) 99
1010
Geometry of Heavy Ion CollisionsGeometry of Heavy Ion Collisions
x
z
y
Non-central Collisions
Reaction plane
N_participants: number of incoming nucleons in the overlap region
N_binary: number of inelastic nucleon-nucleon collisions
Centrality of the collision expressed as percentile of the total cross
section.
N_participants:
N_collisions:
Centrality
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008 1111
FlowFlow(second major discovery at RHIC)(second major discovery at RHIC)
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008 1212
Flow: Evidence of Pressure and Collective Effects
Reaction plane
)(2cos)(21 2
2
RTT
pvdpd
Nd
Origin: In non-central collisions, the pressure converts the initial spatial
asymmetry (almond shape of overlap region) into azimuthal anisotropy of
particle emission
Collective effect
Absent in pp collisions
2v2
The flow is quantified by v2 (elliptic flow parameter) determined from the
azimuthal distribution of particles with respect to the reaction plane ψR
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Every particle flows Mass hierarchy
Large v2 of heavier particles: d.
Even open charm flows (measured through single electrons)
Strong interactions at early stage early thermalization.
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008
The “Flow” Is Perfect
as expected from “perfect fluid” hydrodynamics.as expected from “perfect fluid” hydrodynamics.
~~
mmmpmKE TTT 22
baryonsbaryons
mesonsmesons
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The mass hierarchy disappears if one uses the The mass hierarchy disappears if one uses the transverse kinetic energy:transverse kinetic energy:
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008
The “Flow” knows quarks
baryonsbaryons
mesonsmesons
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Scaling the flow parameters by the valence quark content nq resolves the meson-baryon separation
All this makes the case for sQGP with early thermalization of partonic matter made of
constituent quarks and behaving like a perfect fluid
But there is a (conjectured) quantum limit:But there is a (conjectured) quantum limit:
““A Viscosity Bound ConjectureA Viscosity Bound Conjecture”, P. Kovtun, D.T. Son, A.O. Starinets, hep-th/0405231”, P. Kovtun, D.T. Son, A.O. Starinets, hep-th/0405231
Where do “ordinary” Where do “ordinary” fluids sit wrt this limit?fluids sit wrt this limit?
Itzhak TserruyaItzhak Tserruya
How Perfect is “Perfect” ?First hydrodynamic calculations for RHIC matter have all assumed zero viscosity First hydrodynamic calculations for RHIC matter have all assumed zero viscosity = 0= 0 “perfect fluid” “perfect fluid”
T=10T=101212 K K
Bks
4
RHIC “fluid” RHIC “fluid” mightmightbe at ~1 on this be at ~1 on this scale (!)scale (!)
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Open charm flows!Open charm flows!
Do bottom quarks flow too, or just charm? ANS: VTX in Run-11
Does thermalized charm contribute to J/ via recombination ?
i.e. does J/ flow too? ANS: Run-9 + Run-7!
Elliptic flow of heavy flavor via non-photonic electrons
PRELIMINARYRun-4
Run-7
Rapp & van Hees,
PRC 71, 034907 (2005)
minimum-bias
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008
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J/J/ψψ(the deconfinement probe?)(the deconfinement probe?)
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Physics motivation
ccbarccbar predominantly produced by gluon fusion in the initial predominantly produced by gluon fusion in the initial parton collisions parton collisions probe the created medium : probe the created medium :
– ccbar (quarkonia) suppressed by color screening deconfinement
– open charm (or beauty) energy loss energy density
Anomalous J/ suppression seen at CERN SPS by NA50
At RHIC energy (10x√sNN ) expect much higher suppression
Color Screening
cc
T=0
T≠0
hadron size
confin
ement
color screening
Screening length
NA50 : Pb + Pb
√sNN ~ 17 GeV
nuclear absorption
σabs = 4.18 ± 0.35 mb
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008 2020
First surprise: RHIC vs SPS comparison SPS @ 0<y<1 :SPS @ 0<y<1 :
– √√s ~ 17 GeVs ~ 17 GeV– CNM = CNM = normal nuclear
absorption σabs = 4.18 ± 0.35mb
RHIC @ |y|<0.35 :• √√s = 200 GeVs = 200 GeV• CNM = CNM = shadowing + nuclear
absorption σabs from 0 to 3 mb from 0 to 3 mb (Vogt, nucl-th/0507027)(Vogt, nucl-th/0507027)
Very similar suppression at RHIC and SPS contrary to expectations.-
Second surprise: Rapidity dependence
Stronger suppression at forward rapidity compared to mid-rapidity
Itzhak TserruyaItzhak Tserruya 2121JINR, May 22, 2008JINR, May 22, 2008
J/J/ Au+Au: suppression vs CNM Effects Au+Au: suppression vs CNM Effects
More forward suppression beyond CNM than at mid-rapidityMore forward suppression beyond CNM than at mid-rapidity
Large errors - need higher statistics d+Au data (Run 8)Large errors - need higher statistics d+Au data (Run 8)
J/ RAuAu 200 GeV (Run4)
arXiv:0711.3917|y| < 0.35
1.2 < |y| < 2.2
Cold nuclear matter (CNM) effects derived from d+Au data (run 3):
CNM = Shadowing(EKS) + Breakup = 2.8 mb+1.7
-1.4
J/J/ at RHIC: present status at RHIC: present status Suppression compensated by Recombination ?1) Models with only cold nuclear matter effects don’t quite have enough suppression2) Models with color screening (or comovers) have too much suppression3) Models with color screening (or comovers) AND recombination are in reasonable agreement with the data
J/ χc ’(2S)
ΔE [GeV] 0,64 ~ 0,22 0,05
Td/Tc 2,10 1,16 1,12
Dissociation temperature Td :
F. Karsch et al. (Nucl. Phys. A698(2002) 199c; hep-lat/0106019)
’ J/χc
Satz, J.Phys.G32:R25,2006
Sequential dissociation?
OR
J/J/: outlook: outlook
J/J/ from regeneration should from regeneration should inherit the large charm-quark inherit the large charm-quark elliptic flowelliptic flow
First J/First J/ flow measurement by flow measurement by PHENIX:PHENIX:
– vv22 = –10 ± 10 ± 2 ± 3 % = –10 ± 10 ± 2 ± 3 %
FVTX:
• 4x less ,K decays
• M: 170100 MeV Vertex detectors (VTX,FVTX) &
forward calorimeter (NCC) will give:
• ’ with reduced combinatoric background + sharper mass resolution
• precise open-charm measurements to constrain regeneration pictureLHC ? LHC ?
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Low-mass dileptonsLow-mass dileptons(the chiral symmetry restoration probe)(the chiral symmetry restoration probe)
Origin of mass
1
10
100
1000
10000
100000
1000000
u d s c b t
QCD Mass
Higgs Mass X
Origin of mass:95% of the (visible) mass is due to the spontaneous breaking of the chiral symmetry.
Current quark masses generated by spontaneous
symmetry breaking (Higgs field)
Constituent quark masses generated by spontaneous chiral
symmetry breaking
Many models link the hadron masses to the quark
condensate.
At high T or density 0qq
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Pioneering CERES results Pioneering CERES results at CERN SPS at CERN SPS
Strong enhancement of low-mass e+e- pairs in A-A collisions
(wrt to expected yield from known sources)
No enhancement in pp
nor in pA
Final CERES result
(from 2000 Pb run):Enhancement factor (0.2 <m < 1.1 GeV/c2 ):
2.58 ± 0.32 (stat) ± 0.41 (syst)± 0.77 (decays)
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008 2828
CERES and CERES and NA60NA60• Interpretation: thermal radiation from HG:
+- * e+e-
• Subtract the hadronic cocktail w/o the
* Both NA60 and CERES attribute excess to in-medium broadening of spectral shape (Rapp and Wambach) as opposed to dropping meson mass (Brown et al)
CERES Pb+Au
NA60 In+In
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Low-mass dielectrons at RHICLow-mass dielectrons at RHICarXiv:0706.3034
Significant enhancement of low-mass pairs
Different origin from SPS?
Limited by poor S/B ratio ( 1/200 at m=0.4 GeV/c2)
PHENIX
All pairsCombinatorial BGSignal
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008
Hadron Blind Detector Hadron Blind Detector novel concept for e ID novel concept for e ID →→ Dalitz rejection Dalitz rejection
6 active panels2 side covers
with frame
2 vertical panels
window support
HV panels frame
Windowless Cherenkov detector
50 cm CF4 radiator
CsI reflective photocathode
Triple GEM with pad readout
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Thermal RadiationThermal Radiation (the thermometer)(the thermometer)
Thermal PhotonsThermal Photons High energy density matter is formed at RHIC
If the matter is thermailzed, it should emit “thermal radiation”
The thermal photon spectrum provides a direct measurement of the temperature of the matter
Thermal photons are predicted to be the dominant source of direct photon for 1<pT<3 GeV/c at RHIC energies.
Higher pT: pQCD photon
Lower pT: from hadronic phase
Measurement is difficult since the expected signal is only 1/10 of photons from hadron decays
S.Turbide et al PRC 69 014903 S.Turbide et al PRC 69 014903
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Alternative approach: virtual photons ( low-mass e+e- pairs)
Any source of real emits virtual * with very low mass
If the Q2 (=m2) of virtual photon is sufficiently small, the source strength is the same
The ratio of real photons and virtual photons can be calculated by QED
The real photon yield can be measured from the virtual photon yield, which is observed as low mass e+e- pairs
Excess of low-mass dileptons (wrt hadronic sources) is assigned to direct photons
..**
incl
direct
incl
direct
The idea of measuring direct photon via low mass lepton pair is not new one:
J.H.Cobb, et al, PL 78B, 519 (1978)
3434
TTinitinit via low mass, high p via low mass, high pTT dileptons dileptonsexp + TAA scaled pp
Fit to pp
NLO pQCD (W. Vogelsang)
Fit with exponential + TAA scaled p+p fit:
T = 221 ± 23 ± 18 MeV (central)
arXiv: 0804.4168
pp Au+Au min bias
M < 0.3 GeV/c2 pT = 1-5 GeV/c
JINR, May 22, 2008JINR, May 22, 2008
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High pHigh pTT
suppressionsuppression(first major discovery at RHIC)(first major discovery at RHIC)
3636
Nuclear modification factorNuclear modification factor Zero hypothesis: scale pp to AA with the number of nn collisions Ncoll:
d2NAA/dpTd(b) = Ncoll d2Npp /dpTd = pp TAA(b) ?
d/dpd T
d/dpNd
/
/ )(pR
Tpp2
AA
TAA2
2
2
tAA ddpNdN
ddpNd
Tppcoll
TAA
Quantify “effect” with nuclear modification factor:
• If no “effect”:
RAA < 1 at low pT (soft physics regime)
RAA = 1 at high-pT (hard scattering dominates)
• If “jet quenching”:
RAA < 1 at high-pT
RAA = 1
RAA
RAA < 1
Ncoll /σinel pp
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008
00 ppTT spectra at √ spectra at √ssNNNN = 200 GeV = 200 GeV
AuAu Run4
η=0
p-p
Excellent agreement between measured π0’s in p-p and measured π0’s in Au-Au peripheral collisions
scaled by the number of collisions over ~ 5 decades
70-80% peripheral
Ncoll =12.3 ± 4.0
Central Au-Au collisions yield significantly
suppressed relative to scaled pp yield
0-10% central
Ncoll =975 ± 94.0
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Control: Photons shine, Pions don’t
Direct photons are Direct photons are notnot affected by hot/dense medium affected by hot/dense medium
Rather: Rather: shine shine through consistent with pQCD through consistent with pQCD 3838
Quantitative Analysis of Energy LossQuantitative Analysis of Energy Loss
Itzhak TserruyaItzhak Tserruya 3939JINR, May 22, 2008JINR, May 22, 2008
Jet correlations in Au+Au Jet correlations in Au+Au Away side jet strongly modified in Au+Au compared to p+p collisions
Low/intermediate pT:
-broad away-side
-maxima at Δφ= π +/- 1 rad
High pT
-away-side shape like p+p
-but suppressed yield
•Current conjecture:•Head region -> jet modification (dominant at high pT)•Shoulder region -> medium response (dominant at intermediate pT)
Itzhak TserruyaItzhak Tserruya JINR, May 22, 2008JINR, May 22, 2008
Mach cone?Mach cone?☑ Jets travel faster than the Jets travel faster than the
speed of sound in the medium.speed of sound in the medium.
☑ While depositing energy While depositing energy via gluon radiation. via gluon radiation.
QCD “sonic boom” (?)QCD “sonic boom” (?)
To be expected To be expected in a in a dense fluiddense fluid which is which is strongly-coupledstrongly-coupled
Fluid Effects on Jets ?Fluid Effects on Jets ?
4141
62.4 GeV Au+Au
Summary and Outlook
Onset of heavy flavor energy loss? Emergence of opacity Onset of RHIC’s perfect fluid Energy Scans: where is the critical point? Low-mass dileptons Photon + Jets
Ambitious upgrade program underway RHIC RHIC II x40 luminosity increase Detectors and DAQ upgrades
RHIC has so far been very successful . Much is left to do to further characterize the properties of the “perfect fluid”
LHC is behind the corner. It will offer an unparalleled increase in √s. Will this still create a strongly coupled perfect fluid? Or will we approach the ideal QGP of free gas of quarks and gluons as originally sought?
Active pursuit via Dedicated experiment (ALICE) Targeted studies (CMS, ATLAS)