Bulk Properties of QCD Matter

1

Bulk Properties of QCD Matter
Many thanks to organizers !
Kai Schweda, University of Heidelberg / GSI
Darmstadt
2
Outline

• Introduction
• Hadron Abundances - Tch
• Collective Flow - Tfo, ?
• Heavy Quarks - open charm and quarkonia

3
Introduction
4
Quark Gluon Plasma
Source Michael Turner, National Geographic (1996)

• Quark Gluon Plasma
• Deconfined and
• thermalized state of quarks and gluons
• ? Study partonic EOS at RHIC and LHC(?) Probe
  thermalization using heavy-quarks

5
Nuclear phase diagram

• Heavy quarks with ALICE at LHC
• - Study medium properties
• - pQCD in hot and dense environment
• FAIR/GSI program

Energy scan
6
Colliding Heavy Nuclei
7
High-Energy Nuclear Collisions
Time ?

• 1) Initial condition 2) System evolves 3) Bulk
  freeze-out
• Baryon transfer - parton/hadron expansion -
  hadronic dof
• - ET production - inel. interactions cease
• Partonic dof particle ratios, Tch, mB
• - elas. interactions cease
• Particle spectra, Tth, ltbTgt

Plot Steffen A. Bass, Duke University
8
Collision Geometry
z
Au Au ?sNN 200 GeV
x
Non-central Collisions
Uncorrected
Number of participants number of incoming
nucleons in the overlap region Number of binary
collisions number of inelastic nucleon-nucleon
collisions Charged particle multiplicity ?
collision centrality Reaction plane x-z plane
9
Hadron Abundances
10
Particle Multilplicities
PHOBOS fit HIJING BBar Armesto et
al. AMPT Eskola CGC KLN ASW DPMJET-III EHNRR

• at LHC, dN/dh ? 1000 - 3000
• estimate energy density

Theory points HI at LHC last call for
predictions, CERN, May 2007.
PHOBOS compilation W. Busza, SQM07.
11
EoS from Lattice QCD

• 1) Large increase in ? !
• Large increase in Ndof
• Hadrons vs. partons
• 2) TC 160 MeV
• 3) Boxes indicate max. initial temperatures
• Longest expansion duration at LHC
• Expect large partonic collectivity at LHC

LHC ?
RHIC
SPS
Z. Fodor et al, JHEP 0203014(02) C.R. Allton et
al, hep-lat/0204010 F. Karsch, Nucl. Phys. A698,
199c(02).
12
HI - Collision History

• Tc(ritical) quarks and gluon ? hadrons,
  Tc(ritical) 160 MeV
• Tch(emical) hadron abundancies freeze out
• Tfo particle spectra freeze out

Plot R. Stock, arXiv0807.1610 nucl-ex.
13
Solar Spectrum
Wavelength and Intensity solely determined by
temperature Tsolar 5500 C(at the suns
surface)
Graphik Max-Plack-Institut für Plasmaphysik
14
Wie heiss ist die Quelle ?
1000

• Lichtquelle ? Teilchenquelle
• Häufigkeit von Teilchen am besten beschrieben
  durch T 2 000 000 000 000 ?C 2
  Trillionen ?C
• ? 100 000 mal heisser als im Innern der Sonne !

p
N
K
100.
L
K0
K-
h
Teilchenhäufigkeit
N
X
10.0
f
L
W
1.0
X
W
0.1
0.4
0.8
0
1.6
1.2
E mc2 (GeV)
15
Chemical Freeze-out Model
Refs. J.Rafelski PLB(1991)333 P. Braun-Munzinger
et al., nucl-th/0304013
Hadron resonance ideal gas
Density of particle i
Qi 1 for u and d, -1 for u and d si 1 for s,
-1 for s gi spin-isospin freedom mi particle
mass
Tch Chemical freeze-out temperature mq
light-quark chemical potential ms strange-quark
chemical potential V volume term, drops out for
ratios! gs strangeness under-saturation factor
mB 3mq mS mq-ms
All resonances and unstable particles are decayed
Compare particle ratios to experimental data
16
Hadron Yield - Ratios

• 1) At RHIC
• Tch 160 10 MeV
• ?B 25 5 MeV
• 2) ?S 1.
• ? The hadronic system is thermalized at RHIC.
• 3) Short-lived resonances show deviations.
• ? There is life after chemical freeze-out.

RHIC white papers - 2005, Nucl. Phys. A757,
STAR p102 PHENIX p184 Statistical Model
calculations P. Braun-Munzinger et al.
nucl-th/0304013.
17
Chemical Freeze-Out vs Energy

• With increasing energy
• Tch increases and saturatesat Tch 160 MeV
• Coincides with Hagedorn temperature
• Coincides with early lattice results? limiting
  temperature for hadrons, Tch ? 160 MeV !
• mB decreases, mB 1MeV at LHC
• ? Nearly net-baryon free !

A. Andronic et al., NPA 772 (2006) 167.
18
QCD Phase Diagram
19
Baryon Ratios

• With increasing energy
• Baryon ratios approach unity
• At LHC, pbar / p ? 0.95? with increasing
  collision energy, production of matter and
  anti-matter gets closer

Compilation N. Xu
20
Elementary pp Collisions

• Low multiplicities ? use canonical ensemble
  Strangeness locally conserved!
• particle yields are well reproduced
• Strangeness not equilibrated ! (gs 0.5)

Statistical Model Fit F. Becattini and U. Heinz,
Z. Phys. C 76, 269 (1997).
21
HI - Collision History

• Tc(ritical) quarks and gluon ? hadrons,
  Tc(ritical) 160 MeV
• Tch(emical) hadron abundancies freeze out,
  Tch(emical) 160 MeV
• Tfo particle spectra freeze out

Plot R. Stock, arXiv0807.1610 nucl-ex.
22
Collective Flow
23
Pressure, Flow,

• Thermodynamic identity
• entropy p pressure
• U energy V volume
• t kBT, thermal energy per dof

• In AA collisions, interactions among
  constituentsand density distribution lead to
• pressure gradient ? collective flow
• number of degrees of freedom (dof)
• Equation of State (EOS)
• cumulative partonic hadronic

24
Momentum Distributions

• Typical mass ordering in inverse slope from light
  ? to heavier??
• Two-parameter fit describes yields of p, K, p, L
• Tth 90 ? 10 MeV
• ltbtgt 0.55 ? 0.08 c
• ? Disentangle collective motion from thermal
  random walk

p
p
K (dE/dx)
K (kink)
p
K (dE/dx)
K (kink)
p
L
L
2
AuAu _at_130 GeV, STAR
25
(anti-)Protons From RHIC AuAu_at_130GeV
More central collisions
Centrality dependence - spectra at low momentum
de-populated, become flatter at larger momentum ?
stronger collective flow in more central coll.!
STAR Phys. Rev. C70, 041901(R).
26
Thermal Model Radial Flow Fit

• Source is assumed to be
• in local thermal equilibration Tfo
• boosted in transverse radial direction r f(bs)

boosted
E.Schnedermann, J.Sollfrank, and U.Heinz, Phys.
Rev. C48, 2462(1993)
random
27
D-meson collective flow
Large collective flow velocity ? Spectrum moves
to larger momentum
28
HI - Collision History

• Tc(ritical) quarks and gluon ? hadrons,
  Tc(ritical) 160 MeV
• Tch(emical) hadron abundancies freeze out,
  Tch(emical) 160 MeV
• Tfo particle spectra freeze out, Tfo ? 100 MeV
  ?, K, p

Plot R. Stock, arXiv0807.1610 nucl-ex.
29
Kinetic Freeze-out at RHIC

• 1) Multi-strange hadrons ? and ? freeze-out
  earlier than (p, K, p)
• ?? Collectivity prior to hadronization
• 2) Sudden single freeze-out
• Resonance decays lower Tfo
• for (p, K, p)
• ?? Collectivity prior to hadronization
• ? Partonic Collectivity ?

STAR Preliminary
STAR Data Nucl. Phys. A757, (2005 102), A.
Baran, W. Broniowski and W. Florkowski, Acta.
Phys. Polon. B 35 (2004) 779.
30
Anisotropy Parameter v2
coordinate-space-anisotropy ?
momentum-space-anisotropy
y
py
x
px
Initial/final conditions, EoS, degrees of freedom
31
v2 in the Low-pT Region
P. Huovinen, private communications, 2004

• v2 approx. linear in pT, mass ordering from
  light ? to heavier ?
• characteristic of hydrodynamic flow !
• sensitive to equation of state

32
Non-ideal Hydro-dynamics

• finite shear viscosity ??reduces elliptic flow
• many caveats, e.g. - initial eccentricity ?
  (Glauber, CGC, ) - equation of state -
  hadronic contribution to ?/s

String theory predicts ?/s gt 1/4?
M.Luzum and R. Romatschke, PRC 78 034915 (2008)
P. Romatschke, arXiv0902.3663.
33
Elliptic Flow vs Collision Energy
Glauber initial conditions

• Centrality dependence- initial eccentricity
  ?- overlap area S
• Collision energy dep.- multiplicity density
  dNch/dy
• in central collisions at RHIC, hydro-limit seems
  reached !

NA49, Phys. Rev. C68, 034903 (2003)STAR, Phys.
Rev. C66, 034904 (2002)Hydro-calcs. P. Kolb,
J. Sollfrank, and U. Heinz, Phys. Rev.C62, 054909
(2000).
34
v2 of ? and multi-strange ?

• Strange-quark flow - partonic collectivity at
  RHIC !

QM05 conference M. Oldenburg nucl-ex/0510026.
35
Collectivity, Deconfinement at RHIC

• - v2, spectra of light hadrons
• and multi-strange hadrons
• - scaling with the number of
• constituent quarks
• At RHIC, it seems we have
• ? Partonic Collectivity
• Deconfinement
• ? Thermalization ?
• PHENIX PRL91, 182301(03)
• STAR PRL92, 052302(04)
• S. Voloshin, NPA715, 379(03)
• Models Greco et al, PRC68, 034904(03)
• X. Dong, et al., Phys. Lett. B597, 328(04).

36
Collectivity - Energy Dependence

• Collectivity parameters ltbTgt and ltv2gt increase
  with collision energy
• strong collective expansion at RHIC !ltbTgtRHIC ?
  0.6
• expect strong partonic expansion at LHC, ltbTgtLHC
  ? 0.8, Tfo ? Tch

K.S., ISMD07, arXiv0801.1436 nucl-ex.
37
Partonic Collectivity at RHIC
1) Copiously produced hadrons freeze-out p,K,p
Tfo 100 MeV, ?T 0.6 (c) gt ?T(SPS)
2) Multi-strange hadrons freeze-out
Tfo 160-170 MeV ( Tch), ?T 0.4 (c) 3)
Multi-strange v2 f and multi-strange hadrons ?
and ? do flow! 4) Model - dependent ?/s (0?),1
- 10 x 1/4? Deconfinement Partonic (u,d,s)
Collectivity !
38
Heavy Quarks
39
Heavy ? flavor a unique probe

• mc,b gtgt ?QCD new scale
• mc,b ? const., mu,d,s ? const.
• initial conditions ??????????? test pQCD,
  ?R, ?F probe gluon distribution
• early partonic stage diffusion (?), drag (?),
  flow probe thermalization
• hadronization chiral symmetry
  restoration confinement statistical
  coalescence J/? enhancement / suppression

Q2
X. Zhu, M. Bleicher, S.L. Huang, K.S., H.
Stöcker,N. Xu, and P. Zhuang, PLB 647 (2007) 366.
time
40
Limitations in PDFs

• Most charm created from gluons, e.g. gg ? c
  cbar
• increasing uncertainties in gluon distribution at
  smaller Bjorken x

• Assume y0, pT0, x1x2
• 2 x mcharm ? 3 GeVRHIC (?s0.2TeV) x
  0.015LHC (?s14TeV) x 2x10-4

41
Heavy ? Quark Production
Heavy-quark production at LHC, compared to RHIC
expect factors Charm ? 10 Beauty ? 100
(i) Heavy-quarks abundantly produced at LHC
energies ! (ii) Large theoretical uncertainties ?
energy scan (LHC,FAIR) will help !
Plots R. Vogt,Eur. Phys. J. C, s10052-008-0809-x
(2008).
42
Heavy ? quark Correlations

• c-cbar mesons are correlated
• Pair creation back to back
• Gluon splitting forward
• Flavor excitation flat
• Exhibits strong correlations !
• Baseline at zero clear measure ofvanishing
  correlations !
• ? probe thermalization among partons !

PYTHIA p p _at_ 14 TeV
X. Zhu, M. Bleicher, S.L. Huang, K.S., H.
Stöcker,N. Xu, and P. Zhuang, PLB 647 (2007)
366. G. Tsildeakis, H. Appelshäuser, K.S., J.
Stachel, arXiv 0908.0427.
43
How to measure Heavy-Quark Production

• e.g., D0, c? 123 ?m
• displaced decay vertex is signature of
  heavy-quark decay
• need precise pointing to collision vertex

44
Heavy ? Flavor production at RHIC

• large discrepancy between STAR and PHENIX
  factor gt 2 (!)
• need Si-vertex upgrades(gt 2011)
• large theoretical uncertainties (factor gt 10)
• Measure charm production at RHIC, LHC, FAIR and
  provide input to theory - gluon distribution,
  - scales ?R, ?F

Plot J. Dunlop (STAR), QM2009, Open Heavy-flavor
in heavy-ion collisions, Calcs R. Vogt,Eur.
Phys. J. C, s10052-008-0809-x (2008), M.
Cacciari, 417th Heraeus Seminar, Bad Honnef
(2008).
45
Where does all the charm go?
J??
?c
Ds
D0
D?

• Total charm cross section open charm
  hadrons,e.g. D0, D, Lc, or c,b ? e(?) X
• Hidden-charm mesons, e.g. J/y carry 1 of
  total charm

Statistics plot H. Yang and Y. Wang, U
Heidelberg.
46
D0 ? p K- Reconstruction
p
K-
D0, ct 123 mm
Plot A. Shabetai
47
Open ? Charm Performance

• Measure secondary decay vertex ? Direct
  reconstruction of D0 ? address heavy-quark
  production with 1st year of data taking
• Many other channels, e.g. D, D
• Also single-electrons from heavy-flavor decays

ALICE PPR.vol.II, J. Phys. G 32 (2006) 1295.
Simulation 109 pp, 108 pPb, 107 PbPb
collisions
48
D? meson Identification

• D ? D0 ?
• Identify Dthrough?MD - D0
• Subtract resonance decay to D0
• Two different methods to address total charm
  production

D analysis Yifei Wang, Ph.D. thesis,
University of Heidelberg, in preparation.
49

Viele neue interessante Signale in ALICE bei
LHCz.B. Hadronen mit schweren Quarks (charm
und beauty) D0, D, D, Ds, J/y, y, Lc, Lb,
??????
50
Quarkonia
51
Charmonium

• Bound state of charm- and anti-charm quark
• Hidden-charm meson
• mJ/? 3.1 GeV, rJ/? 0.45 fm, mJ/?' 3.6 GeV,
  JP 1- states
• Minimum formation time ? rJ/? / c 0.45 fm
• Charm-quark production at time scale tc 1/2mc ?
  0.08 fm
• Separation between initial production and
  hadronization (factorization)

52
Debye Screening
53
Quarkonia as a Thermometer

• Check for melting of bottomonium (b-bbar)at
  Tdeconfined ? 2 Tc
• Check for melting of charmonium (c-cbar)at
  Tdeconfined ? 1.2 Tc
• Absolute numbers model-dependent Tfo

54
J/y Production
P. Braun-Munzinger and J. Stachel, Nature 448
(2007) 302.
? suppression,compared to scaled pp ?
regeneration,enhancement
(SPS)
Low energy (SPS) few ccbar quarks in the system
? suppression of J/y High energy (LHC) many
ccbar pairs in the system ? enhancement of J/y ?
Signal of de-confinement thermalization of
light quarks !
55
Statistical Hadronization of Charm

• large charm production at LHC
• strong generation of J/y
• striking centrality dependence
• Signature for QGP formation !
• Initial conditions at LHC ?
• Need to measure total charm production in PbPb !
• Assumes kinetic equilbration of charm !

?scc
A. Andronic, P. Braun-Munzinger, K. Redlich, J.
Stachel, Phys. Lett. B 652 (2007) 259.
56
Charmonium production

• In central PbPb collisions at top SPS energy
• J/? to J/? ratio approaches thermal limit
• Indicates kinetic equilibration of charm

57

• Examples of the ALICE physics potential- Open
  charm D0 ? K- ? (already shown)-
  Quarkonia J/?, ? - Global event properties
• Will be addressed in first year of pp collisions

58
First Physics with ALICE

• Results from simulations
• 1 day of data taking
• Address - multiplicity- mean transverse
  momentum- hadro-chemistry

59
Charmonia via Di-Electron Measurement
Simulation pp coll.

• electron ID with TPC and TRD
• expect 2500 ? mesons per PbPb yearwith good
  mass resolution and S/B

?c1 ?c2
J/?
Simulation 2108 central PbPb collisions
60
Heavy Flavor in Muon Channel
J/y

• muon channel J/?, ? ? ??- (2.5 lt?lt 4) 60000
  J/? and 2000 ?
• initial sample sufficient to study production
  rates of J/? and ? states in muon channel

• b ? ?

?
61
LHC Schedule
Nov 2009 1st pp collisions very short run at
900 GeV Long run of pp collisions at 7- 10
TeV end of 2010 3 - 4 weeks PbPb collisions
at 2.8 - 3.9 TeV
short technical stop over Christmas period
62
ALICE ? Ready for Physics !