1. Raju Venugopalan Brookhaven National Laboratory
The hottest matter on earth: what its made of, how its formed, and how it flows
Raju Venugopalan
Brookhaven National Laboratory
Nordic Winter School, Spätind2016, January 2-7, 2016

2. Outline of lectures
Lecture I: QCD and the Quark-Gluon Plasma: elements of a
“standard model” paradigm
Lecture II: The problem of thermalization in heavy-ion collisions

3. The physics of heavy-ion collisions
HI theory draws concretely on concepts in perturbative QCD, the gauge-gravity duality, lattice QCD & other non-perturbative dynamics, reaction-diffusion dynamics, topological effects, plasma instabilities, kinetic theory & hydrodynamics, quantum chaos, Bose-Einstein condensates, weak wave turbulence,…
Heavy-Ion collisions are of intrinsic interest since they offer
the possibility of studying on earth the dynamics of
non-Abelian fluids

4. Early Universe

5. Matter in unusual conditions
E. Fermi: “ Notes on Thermodynamics and Statistics ” (1953)

6. On heating strongly interacting matter
RHIC
Neutron stars
Neutron stars
Neutron stars
On heating strongly interacting matter
Thus, our ignorance of microscopic
physics stands as a veil, obscuring our view of the
very beginning.
Steven Weinberg, The First Three Minutes (1973)

7. E. Fermi: “ Notes on Thermodynamics
RHIC
Neutron stars
Neutron stars
Neutron stars
QCD : lifting the veil
E. Fermi: “ Notes on Thermodynamics
and Statistics ” (1953)
Hagedorn (1965)
Lee-Wick matter (1974)
Collins-Perry/Cabibbo-Parisi (1975)
Quark-Gluon Plasma (QGP)
Shuryak (1978)

8. QCD: theory of the strong interaction
Quark fields
Gluon fields
Symmetries of the QCD Lagrangian:
Gauge “color” symmetry: unbroken but confined
Global “chiral” symmetry: exact for massless quarks
Baryon number and axial charge (m=0) are conserved
Scale invariance:
v) Discrete C,P & T symmetries i ii
iii
Chiral, Axial, Scale and (in principle) P & T are broken
by Vacuum / Quantum effects

11. QCD: asymptotic freedom
Gross,Wilczek, Politzer
Coupling grows weaker
with increasing momentum
transfer (shorter distances)
Super-dense and Super-hot QCD matter is a weakly coupled gas of quarks and gluons -- analytical computations feasible
Cabibo-Parisi; Collins-Perry

12. QCD: Infrared Slavery
Potential between static
quark-anti-quark pair
grows linearly at large distances -
intuitive picture of confinement
QCD matter is strongly interacting at low Temp. and Density
- static properties computed using numerical lattice methods

13. QCD: Chiral symmetry breaking
Quantum QCD vacuum:
Chiral condensate: spontaneously generate mass via
Nambu-Goldstone mechanism
mq ~ 10 MeV ; mN ~ 1 GeV
Axial anomaly:
Quantum violation of U(1)A
Chiral symmetry restoration at large T:

14. Universe evolved from Quarks & Gluons to Hadrons
How did this happen ?
Is there a phase transition (vapor to liquid) transition ?

15. Phase Diagram of Water phase transition line
Ágnes Mócsy
Phase Diagram of Water
Physicists’ way of mapping the phase that will exist for a given pressure and temperature
phase transition line

16. phase diagram of nuclear matter
Ágnes Mócsy
phase diagram of nuclear matter T B 
Hadron Gas
Quark Gluon Plasma
Color Superconductor
Critical Point 
Normal Nuclear Matter
Quarkyonic
Nuclear density
Temperature
QCD Phase diagram
Major theoretical and experimental effort to map and explore this rich phase structure.

17. Where to study QCD matter
Peter Steinberg
Where to study QCD matter
Big Bang
Only one chance…
Lattice QCD
Neutron stars
RHIC
Who wants to wait?…

19. Lattice results for Energy & Entropy Density
QCD at finite T:
Lattice results for Energy & Entropy Density
C. Ratti, plenary talk at Quark Matter 2015

20. Lattice results for Chiral Symmetry Restoration
QCD at finite T:
Lattice results for Chiral Symmetry Restoration
z = t/h1/βδ t = (T-Tc)/Tc ; h=ml/ms
Universality class of continuum QCD: 3d-O(4) spin models
Nice review, Dong et al.,

21. QCD at finite T:
Lattice results for Chiral Symmetry Restoration
O(4) scaling of chiral susceptibility

22. Gauge theories at finite T:
The finite temperature phase diagram of QCD-like theories
The QCD transition is a crossover transition
Aoki et al, Nature 443 (06) 675

23. QCD at finite T: The deconfinement transition
Thermal expectation value of renormalized `Polyakov loop’ – order parameter for deconfinement in a pure gauge theory
F=free energy of heavy quark-antiquark pair at spatial infinity
Difference in susceptibilities
probe release of quark degrees of freedom

24. Lattice QCD at finite T:
Free energy of heavy static quarks computed from the product of
the traces of two Polyakov loops
Borsanyi et al., arXiv:
Plasma screens potential between heavy quarks
Suppression of heavy quarks suggested as possible signature of
Quark-Gluon Plasma formation - Matsui, Satz 1986

25. QCD phase diagram