Extreme Holography David Mateos ICREA & University of Barcelona - PowerPoint PPT Presentation

Extreme Holography David Mateos ICREA & University of Barcelona with M. Attems, Y. Bea, J. Casalderrey, A. Faedo, A. Kundu, I. Papadimitriou, C. Pantelidou, D. Santos-Oliván, W. van der Schee, C. F. Sopuerta, J. Tarrio, M. Triana and M. Zilhão

QCD in extreme conditions Holography String Theory

Plan • All you need to know about: ‣ QCD ‣ String theory ‣ Holography • Holographic heavy ion collisions with phase transitions. • Holographic color superconductivity.

Plan • All you need to know about: ‣ QCD ‣ String theory ‣ Holography • Holographic heavy ion collisions with phase transitions. HOT • Holographic color superconductivity. COLD

QCD

Why is QCD hard? Strength of interaction depends on energy ⇥ 1 ( E ) Λ QCD ∼ 200 MeV

Why is QCD hard? ⇥ Asymptotic freedom The Nobel Prize in Physics 2004 1 D. Gross D. Politzer F. Wilczek • Can use perturbation theory. ( E ) Λ QCD ∼ 200 MeV

Why is QCD hard? Strong coupling ⇥ 1 ( E ) Λ QCD ∼ 200 MeV

Why is QCD hard? Strong coupling ⇥ • Only 1 st - principle systematic tool is lattice formulation + supercomputer. 1 ( E ) Λ QCD ∼ 200 MeV

Why is QCD hard? Strong coupling ⇥ • Only 1 st - principle systematic tool is lattice formulation + supercomputer. • Limited applicability to non - equilibrium or non - zero quark density. 1 ( E ) Λ QCD ∼ 200 MeV

QCD in extreme conditions • QCD at extremely high energy density and/or quark density. • In equilibrium, this physics is captured by the QCD phase diagram. • For the purpose of this talk:

QCD phase diagram T Quark - Gluon Plasma T c ~ Λ QCD q, q, q, q } { q q, q } ¯ q ¯ q ¯ q, q, q { q Hadrons n q

QCD phase diagram T Quark - Gluon Plasma Can be created in the lab via heavy ion collisions at RHIC and LHC T c ~ Λ QCD q, q, q, q } { q q, q } ¯ q ¯ q ¯ q, q, q { q Hadrons n q

QCD phase diagram T Quark - Gluon Plasma T c ~ Λ QCD Critical point q, q, q, q } { q q, q } ¯ q 1 st - order transition ¯ q ¯ q, q, q { q Hadrons n q

QCD in extreme conditions T Quark - Gluon Plasma Critical point searched for at RHIC ( now ) and at FAIR and NICA ( future ) . T c ~ Λ QCD Critical point q, q, q, q } { q q, q } ¯ q 1 st - order transition ¯ q ¯ q, q, q { q Hadrons n q

QCD phase diagram t hydro Collision time T ‣ Far - from - equilibrium dynamics ‣ Hydrodynamics ‣ Hadronization Quark - Gluon Plasma T c ~ Λ QCD Critical point q, q, q, q } { q q, q } ¯ q 1 st - order transition ¯ q ¯ q, q, q { q Hadrons n q

QCD phase diagram t hydro Collision time T ‣ Far - from - equilibrium dynamics ‣ Hydrodynamics ‣ Hadronization Quark - Gluon Plasma ‣ Theoretical challenge. ‣ W e will see what holography can say. T c ~ Λ QCD Critical point q, q, q, q } { q q, q } ¯ q 1 st - order transition ¯ q ¯ q, q, q { q Hadrons n q

QCD phase diagram T Quark - Gluon Plasma T c ~ Λ QCD Critical point q, q, q, q } { q q, q, q, q } ¯ q 1 st - order transition ¯ q, q } q { q, ¯ q, q, q { q Color superconductor Alford, Rajagopal & Wilczek ’99 q, q } { q Hadrons q, q, n q

QCD phase diagram Could be realized at the core of neutron stars T Quark - Gluon Plasma ‣ Can be studied via weak - coupling methods only at n q → ∞ . ‣ W e will see what holography can say. T c ~ Λ QCD Critical point q, q, q, q } { q q, q, q, q } ¯ q 1 st - order transition ¯ q, q } q { q, ¯ q, q, q { q Color superconductor Alford, Rajagopal & Wilczek ’99 q, q } { q Hadrons q, q, n q

String Theory

String theory • Perturbatively it is quantum theory of 1 - dimensional objects.

String theory • Perturbatively it is quantum theory of 1 - dimensional objects. • Di ff erent vibration modes behave as particles of di ff erent masses and spins: M

String theory • Perturbatively it is quantum theory of 1 - dimensional objects. • Di ff erent vibration modes behave as particles of di ff erent masses and spins: M M=0, Spin=2: Graviton! Theory of Quantum Gravity

String theory • Non - perturbatively, string theory is not only a theory of strings: Open strings D - branes

Holography

Holography from two equivalent descriptions QCD - like theory in flat space quark gluons

Holography from two equivalent descriptions QCD - like theory in flat space AdS 5 String theory in AdS 5 - like space

Holography from two equivalent descriptions QCD - like theory in flat space = Boundary of AdS 5 AdS 5 String theory in AdS 5 - like space

QGP = BH ¯ q q q Black Hole Confined Deconfined

Limitations • At present the dual of QCD is not known.

Limitations • At present the dual of QCD is not known. • Therefore holography is not a tool for precision QCD physics.

Limitations • At present the dual of QCD is not known. • Therefore holography is not a tool for precision QCD physics. • However, it may still provide useful insights.

Limitations • At present the dual of QCD is not known. • Therefore holography is not a tool for precision QCD physics. • However, it may still provide useful insights. • In particular, holography is the only first - principle tool if strong coupling + far from equilibrium.

Holographic Collisions

What we would like to do Heavy ion collisions in QCD

What we can do Holographic heavy ion collisions Caricatures: Lumps of energy and charge Gravitational + electromagnetic waves

Formation of the QGP Black hole horizon

Strategy Holographic heavy ion collisions Read o ff boundary stress tensor Solve classical Einstein equations

Example: CFT Collision region Incoming shocks Receding fragments QGP ε / Λ 4 0.02 Λ

Collisions with a crossover Attems, Casalderrey, D.M., Santos-Olivan, Sopuerta, Triana & Zilhao ’16 QCD deconfinement is rapid crossover ( lattice ) Holographic theory has scale Λ ~ T c Z. Fodor et al ’02 Observations: • O Can think of Λ as mass term for dim - 3 scalar operator .

Many paths to equilibrium Attems, Casalderrey, D.M., Santos-Olivan, Sopuerta, Triana & Zilhao ’16 • Define several characteristic times/processes leading to equilibration: � � � � P L P T ‣ Hydrodynamization: and are well described by hydro. � � P L P T ‣ Isotropization: and become equal. ¯ P eq P ‣ EoSization: and become equal. � h O i eq h O i ‣ Scalar relaxation: and become equal.

� � � Many paths to equilibrium Attems, Casalderrey, D.M., Santos-Olivan, Sopuerta, Triana & Zilhao ’17 • Many possible orderings. t hyd T hyd t EoS T hyd t cond T hyd t iso much longer Collision energy

� � � Many paths to equilibrium Attems, Casalderrey, D.M., Santos-Olivan, Sopuerta, Triana & Zilhao ’17 • Many possible orderings. t hyd T hyd t EoS T hyd t cond T hyd t iso much longer Collision energy • Equilibration is very non - trivial process.

� � � Many paths to equilibrium Attems, Casalderrey, D.M., Santos-Olivan, Sopuerta, Triana & Zilhao ’17 • Many possible orderings. t hyd T hyd t EoS T hyd t cond T hyd t iso much longer Collision energy • Equilibration is very non - trivial process. • Hydrodynamics can be applicable even when “everything looks far from equilibrium”: ‣ Without isotropy ‣ Without EoS ‣ Without scalar relaxation

Collisions across a 1 st - order phase transition Attems, Bea, Casalderrey, D.M., Triana & Zilhao (to appear) 0.04 0.03 ε / Λ 4 0.02 0.01 0.00 0.226 0.228 0.230 0.232 0.234 0.236 T / Λ

Collisions across a 1 st - order phase transition Attems, Bea, Casalderrey, D.M., Triana & Zilhao (to appear) 0.04 ε / Λ 4 0.03 0.02 ε / Λ 4 0.02 0.01 0.00 0.226 0.228 0.230 0.232 0.234 0.236 T / Λ Extremely high energy: Λ Recover CFT result

Collisions across a 1 st - order phase transition Attems, Bea, Casalderrey, D.M., Triana & Zilhao (to appear) 0.04 ε / Λ 4 0.03 0.02 ε / Λ 4 0.02 0.01 0.00 0.226 0.228 0.230 0.232 0.234 0.236 T / Λ Λ ε / Λ 4 ε / Λ 4 0.02 0.02 Λ Λ

Collisions across a 1 st - order phase transition Attems, Bea, Casalderrey, D.M., Triana & Zilhao (to appear) 0.04 ε / Λ 4 0.03 0.02 ε / Λ 4 0.02 0.01 0.00 0.226 0.228 0.230 0.232 0.234 0.236 T / Λ Λ ε / Λ 4 Long - lived, quasi - static blob 0.02 well described by 2 nd - order hydro Λ

B lob well described by 2nd-order hydrodynamics Attems, Bea, Casalderrey, D.M., Triana & Zilhao (to appear) + ∂ spatial + ∂ 2 T µ ν = T ideal µ ν spatial

B lob well described by 2nd-order hydrodynamics Attems, Bea, Casalderrey, D.M., Triana & Zilhao (to appear) + ∂ spatial + ∂ 2 T µ ν = T ideal µ ν spatial Time evolution at mid - rapidity Snapshots of spatial profile after hydrodynamization