Dynamics of Strongly Interacting Matter
Elena Bratkovskaya
for the FIAS Strongly Interacting Matter Groups
(Fellows: Marcus Bleicher, Igor Mishustin, Hannah Petersen, Stefan Schramm)
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Research at FIAS
FIAS
24.11.14
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Heavy-ion collisions
 Heavy-ion collision experiment
 ‚re-creation‘ of the Big Bang conditions in laboratory:
matter at high pressure and temperature
 Heavy-ion accelerators:
Relativistic-Heavy-Ion-Collider - RHIC
(Brookhaven): Au+Au up to 21.3 A TeV
24.11.14
Large Hadron Collider LHC (CERN):
Pb+Pb up to 574 A TeV
lQCD
Facility for Antiproton and Ion
Research – FAIR (Darmstadt)
(Under construction)
Au+Au up to 10 (30) A GeV
2/15
The phases of QCD
The phase diagram of Quantum Chromo Dynamics (QCD)
Analogy to ‚macro-world‘:
the water-ice-vapor phase
transition
 Study of the phase
transition from hadronic to
partonic matter –
Quark-Gluon-Plasma
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Signals of the phase transition
 Heavy-ion collision:
Initial state: Au+Au
Quark-Gluon Plasma (QGP)
Hadronization
Final hadrons + leptons
PHSD
Hadronic degrees of freedom  QGP  hadronic degrees of freedom
Experiment: measures final hadrons and leptons
How to learn about physics of the QGP from data?
time
Compare with theory!
1 event: Au+Au, 21.3 TeV
 Requires theoretical models which
describe the dynamics of heavy-ion
collisions during the whole time evolution!
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Heavy Ion Transport Groups :
The goal: to study the properties of strongly interacting parton-hadron matter
under extreme conditions from a microscopical point of view
Realization: dynamical many-body transport models
Research group of Elena Bratkovskaya
Parton-Hadron-String Dynamics
transport approach (PHSD)
Research group of Marcus Bleicher
Ultrarelativistic Quantum Molecular
Dynamics (UrQMD)
UrQMD
Research group of Hannah Petersen
(Helmholtz Young Investigator Group)
Dynamical Description of Heavy-Ion
Reactions at FAIR
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Dynamical model for HIC
 UrQMD - ‚Hybrid‘ model
Initial state: Au+Au
QGP: ideal hydro with QGP EoS
 PHSD model
Initial state: Au+Au
PHSD
hadronic
freeze-out
QGP: non-equilibrium
microscopic transport model
with lQCD EoS
‚after burner‘:
hadron-string transport model
dynamical
hadronization
off-shell
hadron-string transport
model
time 
QGP: Dynamical QuasiParticle model (DQPM) - strongly interacting massive quasi-particles
(quarks and gluons with spectral functions) in self-generated mean-field
 Allows for a comprehensive study of HIC dynamics!
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Physics with HIC
 PHSD and UrQMD transport models provide a unique description of pA, pA, anti-pA
and AA dynamics from low (~100 MeV) to ultrarelativistic (>500 TeV) energies
Low
0.1
Intermediate
1
SIS
100
BM@N FAIR NICA
Baryonic matter
||
Meson and baryon
spectroscopy
In-medium effects
EoS
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High
Ultra-High
1000
SPS
‚Mixed‘ phase:
hadrons + quarks and gluons
||
 In-medium effects
 Chiral symmetry restoration
 Phase transition to sQGP
 Critical point in the QCD
phase diagram
Ebeam [A GeV]
10000
RHIC
100000
LHC
QGP: quarks and gluons
||
 Properties of sQGP
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Research projects in 2014
 Charm quark dynamics in the QGP
 study of the properties of hot and dense
nuclear and partonic matter by ‚hard probes‘:
 Transport properties of charm
quarks are described by the
diffusion coefficient Ds
QGP by DQPM
hadron
gas
QGP
pQCD
DQPM
 pQCD vs hadron gas: discontinuity in Ds
 Dynamical QuasiParticle Model (DQPM): continuous transition from hadron gas to
QGP (crossover type)  strongly interacting partonic system above TC
H. Berrehrah et al, Phys. Rev. C 89 (2014) 054901; aXiv:1405.3243; Phys. Rev. C 90 (2014) 051901
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Research projects in 2014
 Electromagnetic probes of the QGP
– dileptons (e+e- pairs) and direct photons g
 Thermal photons:
• QGP
• Hadron gas
photon yield
 v2 ‘puzzle’:
PHENIX and ALICE - exp. observation of
strong elliptic flow of direct photons v2(gdir)~ v2(p)
Problem: QGP radiation occurs at early times when
flow is not yet developed  theor. expected v2(gQGP) 0
photon elliptic flow
 Strong elliptic flow has a
hadronic origin:
mm, mB bremsstrahlung and
binary reactions mmmg
The QGP causes the
strong elliptic flow of
photons indirectly, by
enhancing the v2 of final
hadrons due to the partonic
interactions
 LHC (similar to RHIC): PHSD: hadronic photons dominate spectra and v2
O. Linnyk et al., Phys. Rev. C 88 (2013) 034904; Phys. Rev. C 89 (2014) 034908
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UrQMD
Research projects in 2014
 Development of viscous ‚Hybrid‘ model = UrQMD + viscous hydro
Elliptic flow v2: viscous vs. ideal hydro
ideal
viscous
Karpenko et al, WPCF 14
 Viscous hybrid approach reproduces
decrease of v2 at high pT as well as a weak
energy dependence of v2
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J. Auvinen and H. Petersen, PRC 88 (2013)
 Initial non-equilibrium evolution
largely compensates for shortened
hydrodynamic stage at lower beam
energies
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UrQMD
Research projects in 2014
 Directed flow v1 as a signal of 1st order phase transition
Ideal hydro: non-monotonic dependence of proton v1 slope at midrapidity F =
d 1
|y =0
dy
ideal hydro
collapse of flow
Plot from H. Stöcker, Nucl. Phys. A 750, 121 (2005)
 Dip structure only reproduced with pure fluid
hydro calculation with isochronous (IC=equal
time) freeze-out and first order phase transition
Plot from J.Brachmann et al., Phys.Rev. C, 61, 2000
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Hybrid/UrQMD/Hydro: J. Steinheimer, J. Auvinen,
H. Petersen, M. Bleicher, H. Stöcker, PRC 89 (2014) 054913
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UrQMD
Research projects in 2014
 Directed flow v1 as a signal of 1st order phase transition
 Directed flow v1 is formed at an early stage of the
nuclear interaction
 Baryons are reaching positive and mesons –
negative value of v1
 v1: smooth crossover?!
PHSD/HSD: V. Konchakovski et al., PRC90 (2014) 14903; arXiv:1408.4313
Hybrid/UrQMD/Hydro: J. Steinheimer, J. Auvinen, H. Petersen,
M. Bleicher, H. Stöcker, PRC 89 (2014) 054913
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Research projects in 2014
 Strong Interaction Physics
Group S. Schramm
 Effective chiral models of quarkhadron systems for a wide range of
densities and temperatures
 baryon masses generated by scalar field
includes nucleons, hyperons, mesons
hadrons / quarks couple via condensates
 Idea: relate results from different fields:
•
•
•
•
Neutron
Hyper
Hybrid
hybrid
twin star
Stars
Use for equation of state (heavy-ion simulations)
Comparison with lattice QCD
Structure of exotic nuclei and hypernuclei
Neutron star physics
 Exotic nuclear structures in the star crust
crust simulation
with GPU code
(speed-up of more
than 200)
generates small-radius and heavy-mass stars
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Phys. Lett. B736, 241 (2014)
J. Phys. G40, 085001 (2013)
Phys. Rev. C87, 015804 (2013)
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Research projects in 2014
Group I. Mishustin
 Geant4-based Monte Carlo model for Heavy-Ion Therapy (MCHIT) :
developed at FIAS to investigate physical interactions of accelerated
nuclei with tissue-like media.
MCHIT describes dose distributions (a), yields of nuclear fragments (b),
microdosimetry spectra used for evaluating biological endpoints (c)
healthy tissues
Pshenichnov, Mishustin, Greiner, PMB 50 (2005) 5493
Burigo, Pshenichnov, Mishustin, Bleicher, NIM B 320 (2014) 89
tumor
(c)
Deep seated
tumor
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(a)
(b)
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Interdisciplinary connections
Common research projects
at FIAS (2014):
Study of hot and dense matter;
strange matter and hypernuclei:
groups of Marcus Bleicher,
Hannah Petersen,
Elena Bratkovskaya,
Stefan Schramm,
Igor Mishustin
Complex numerical simulations:
 groups of Hannah Petersen
and Volker Lindenstruth
(Dr. Matthias Kretz);
 groups of Elena Bratkovskaya
and Ivan Kisel (PhD student
Volodymyr Vovchenko)
Monte Carlo simulations for
heavy-ion therapy:
groups of Marcus Bleicher and
Igor Mishustin (Dr. Lucas Burigo)
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