Christoph Blume University of Frankfurt Winter Workshop on Nuclear Dynamics, 2010, Ochos Rios, Jamaica Particle Production at the SPS and the QCD Phase Diagram Christoph Blume University of Frankfurt 26 th Winter Workshop on Nuclear Dynamics Ocho Rios, Jamaica January 2010
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Christoph Blume University of Frankfurt Winter Workshop on Nuclear Dynamics, 2010, Ochos Rios, Jamaica Particle Production at the SPS and the QCD Phase.
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Christoph Blume
University of Frankfurt
Winter Workshop on Nuclear Dynamics,
2010, Ochos Rios, Jamaica
Particle Production at the SPS and the QCD Phase DiagramParticle Production at the SPS and the QCD Phase Diagram
How to probe different regions of the QCD phase diagram?
Variation of center-of-mass energyWay of scanning different freeze-out parameters T and μB
Variation of system sizeHow do T and μB depend on system size
Core corona approach
Critical point searchSystematic study of multiplicity fluctuationsOther observables
How to probe different regions of the QCD phase diagram?
Variation of center-of-mass energyWay of scanning different freeze-out parameters T and μB
Variation of system sizeHow do T and μB depend on system size
Core corona approach
Critical point searchSystematic study of multiplicity fluctuationsOther observables
QCD Phase Diagram
Christoph Blume WWND 2010, Ocho Rios, Jamaica 3
A. Andronic et al., arXiv: 0911.4806
L. McLarren and R.D. Pisarski,Nucl. Phys. A796,83 (2007).
Christoph Blume WWND 2010, Ocho Rios, Jamaica 4
QCD Phase DiagramExperimental Access
High energies (RHIC/LHC)B small
System reaches QGP phase
Low energies (AGS)B large
System stays in hadronic phase
In between (SPS/FAIR)Variation of B by changing sNN
Possible to localize critical point?
Other control parameters (e.g. system size)?
Christoph Blume WWND 2010, Ocho Rios, Jamaica 5
Significant change of shape at SPS energies
Peak dip structure
Rapid change of net-baryon density at y = 0
Strong variation of B
Significant change of shape at SPS energies
Peak dip structure
Rapid change of net-baryon density at y = 0
Strong variation of B
Energy DependenceNet-Baryon Distributions
BRAHMSPhys. Rev. Lett. 93 (2004), 102301
158A GeVPhys. Rev. Lett. 82 (1999), 2471
E802Phys. Rev. C 60 (1999), 064901
NA49 preliminary
Central Pb+Pb/Au+Au
6
Energy DependenceExample: /π- and /π-Ratios
NA49 dataPhys. Rev. C78, 034918 (2008)
Statistical models
Generally good description at allenergies
Fixes parameters T and μB
NA49 dataPhys. Rev. C78, 034918 (2008)
Statistical models
Generally good description at allenergies
Fixes parameters T and μB
|y| < 0.4
|y| < 0.5
SHM(B): A. Andronic et al. Nucl. Phys. A 772, 167 (2006).UrQMD: M. Bleicher et al., J. Phys. G 25, 1856 (1999) and private communicationHSD: E. Bratkovskaya et al., Phys. Rev. C69, 054907 (2004)
/
/−
-/ +/− = 1.5 (+ + -)
Christoph Blume WWND 2010, Ocho Rios, Jamaica
Christoph Blume WWND 2010, Ocho Rios, Jamaica 7
Results from differentbeam energiesAnalysis of particle yieldswith statistical models
Freeze-out points reach QGP phase boundary at top SPS energies
Caveat: Disagreement betweendifferent LQCD results on TC
Results from differentbeam energiesAnalysis of particle yieldswith statistical models
Freeze-out points reach QGP phase boundary at top SPS energies
Caveat: Disagreement betweendifferent LQCD results on TC
QCD Phase DiagramData Points
F. Becattini et al., Phys Rev. C69, 024905 (2004).
System Size DependenceFreeze-out Parameter
Christoph Blume WWND 2010, Ocho Rios, Jamaica 8
How do freeze-out parameters dependon system size ?
Statistical model fitsresult in different T
Central reactions
Way to move around in phase diagram?
How do freeze-out parameters dependon system size ?
Statistical model fitsresult in different T
Central reactions
Way to move around in phase diagram?
F. Becattini et al.,Phys. Rev. C73, 044905 (2005)
Christoph Blume WWND 2010, Ocho Rios, Jamaica 9
System Size Dependence(Anti-)Proton y-Spectra
Preliminary data by NA49
Minimum bias Pb+Pb at 158A GeV
Preliminary data by NA49
Minimum bias Pb+Pb at 158A GeV
NA49 preliminary
NA49 preliminary
p p
H. Ströbele et al.arXiv:0908.2777
Christoph Blume WWND 2010, Ocho Rios, Jamaica 10
System Size DependenceNet-Protons
NA49 preliminary p - pCen.
Per.
No strong system sizedependence observed
No strong system sizedependence observed
Peripheral spectrum slightly more pronounced y-dependencethan central one
Beam rapidity not measured!
In measured rapdity range similar shape like p+p data
⇒ System size has no big influence on μB
p+p Data:M. Aguilar-Benitz et al.,Z. Phys. C 50 (1991), 405.
NA49 preliminary
central
per.
p+p
11
System Size DependenceEnhancement factors of , , and
Enhancement factor
p+p data: NA49
Early saturation
Nw > 60
Core Corona Model
f (NW) = fraction of nucleons that scatter more than once
F. Becattini and J. Manninen, J. Phys. G35, 104013 (2008)K. Werner, Phys. Rev. Lett. 98, 152301 (2007)J. Aichelin and K. Werner, arXiv:0810.4465
Enhancement factor
p+p data: NA49
Early saturation
Nw > 60
Core Corona Model
f (NW) = fraction of nucleons that scatter more than once
F. Becattini and J. Manninen, J. Phys. G35, 104013 (2008)K. Werner, Phys. Rev. Lett. 98, 152301 (2007)J. Aichelin and K. Werner, arXiv:0810.4465€
M NW( ) = NW f NW( ) MCore[
+ 1− f NW( )( )MCorona ]
C+C
00
211
yyw dyppdn
dyPbPbdn
NE
158A GeV
Si+SiPb+Pb
Christoph Blume WWND 2010, Ocho Rios, Jamaica
12
System Size DependenceAverage Transverse Mass: mt-m0
Similar dependence asfor multiplicities observed
Early saturation Nw > 60
Core Corona model
f(NW) = fraction of nucleons, that scatter more than once
F. Becattini and J. Manninen, J. Phys. G35, 104013 (2008)K. Werner, Phys. Rev. Lett. 98, 152301 (2007)J. Aichelin and K. Werner, arXiv:0810.4465
NA49 data: Phys. Rev. C80 (2009), 034906.
Similar dependence asfor multiplicities observed
Early saturation Nw > 60
Core Corona model
f(NW) = fraction of nucleons, that scatter more than once
F. Becattini and J. Manninen, J. Phys. G35, 104013 (2008)K. Werner, Phys. Rev. Lett. 98, 152301 (2007)J. Aichelin and K. Werner, arXiv:0810.4465
NA49 data: Phys. Rev. C80 (2009), 034906.
CoronatW
CoretWWWt
mNf
mNfNNm
1
|y| < 0.4 (0.5)
Christoph Blume WWND 2010, Ocho Rios, Jamaica
System Size DependenceCore-Corona: Central ↔ Peripheral
Christoph Blume WWND 2010, Ocho Rios, Jamaica 13
Core Corona model
f(Npart) = fraction of nucleons, that scatter more than once
Centrality dependenceStronger for smaller systems
Central reactionsStill clear change of fmax
with system size
Compare fmax(Pb+Pb) ≈ 0.9and fmax(C+C) ≈ 0.65
⇒ apparent change of T + μB
Not real, just different mixture of core and corona
Thanks to K. Reygers for providing the Glauber code
Core Corona model
f(Npart) = fraction of nucleons, that scatter more than once
Centrality dependenceStronger for smaller systems
Central reactionsStill clear change of fmax
with system size
Compare fmax(Pb+Pb) ≈ 0.9and fmax(C+C) ≈ 0.65
⇒ apparent change of T + μB
Not real, just different mixture of core and corona
Thanks to K. Reygers for providing the Glauber code
System size is not a good control parameterto move around inQCD phase diagram
System size is not a good control parameterto move around inQCD phase diagram
System Size DependenceCore-Corona: Asymmetric Systems
Christoph Blume WWND 2010, Ocho Rios, Jamaica 14
Core Corona model
f(Npart) = fraction of nucleons, that scatter more than once
Centrality dependence
Peculiar shape for small projectiles (e.g. C, O, Si, S)
Core Corona model
f(Npart) = fraction of nucleons, that scatter more than once
Centrality dependence
Peculiar shape for small projectiles (e.g. C, O, Si, S)
Limiting case: p + A
f(Npart) = 1 / Npart
Model applicable in p+A?First attempt in T. Šuša et al., Nucl. Phys. A698 (2002) 491c
Christoph Blume WWND 2010, Ocho Rios, Jamaica 15
Critical PointTheoretical Predictions
M. Stephanov,CPOD conference 09
Lattice QCD difficult for B > 0
Sign problem in Fermion-determinant
Progress in recent years(e.g. Fodor and Katz)
Results strongly divergent
Typically B > 200 MeV
Perhaps no critical point at allfor B < 500 MeV (de Forcrand and Philipsen)
Lattice QCD difficult for B > 0
Sign problem in Fermion-determinant
Progress in recent years(e.g. Fodor and Katz)
Results strongly divergent
Typically B > 200 MeV
Perhaps no critical point at allfor B < 500 MeV (de Forcrand and Philipsen)
Critical PointObservables
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Elliptic flow v2
R. A. Lacey et al., arXiv:0708.3512: η/s versus T and μB.
E. Shuryak, arXiv:hep-ph/0504048: Decrease (increase) of baryon (meson) flow.Higher experimental precision required.
mt-Spectra of baryons and anti-baryonsAsakawa et al., Phys. Rev. Lett. 101 (2008) 122302.Higher experimental precision required.
Di-pion (sigma) intermittency studyT. Anticic et al., arXiv 0912.4198.No unambiguous signal seen yet