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

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

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

Early Universe

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

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)

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)

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

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

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

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:

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

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

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.

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?…

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

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., 1504.05274

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

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

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

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:1501.02173 Plasma screens potential between heavy quarks Suppression of heavy quarks suggested as possible signature of Quark-Gluon Plasma formation - Matsui, Satz 1986

QCD phase diagram