Thomas Mehen
Duke University
mehen@phy.duke.edu

Anna Stasto
Pennsylvania State University
astasto@phys.psu.edu

Program Coordinator:
Inge Dolan
inge@u.washington.edu
(206) 685-4286

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11:00-12:00, Room C520, Physics and Astronomy Tower
Eugenio Megias, "Gravitational anomaly and transport"

Abstract: Quantum anomalies give rise to new transport phenomena. In particular a magnetic field can induce an anomalous current via the chiral magnetic effect (K. Fukushima, D. Kharzeev, H.J. Warringa, Phys. Rev. D78 (2008) 074003) and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect (D. T. Son and P. Surowka, Phys. Rev. Lett. 103 (2009) 191601). The related transport coefficients can be calculated via Kubo formulas (I. Amado, K. Landsteiner, F. Pena-Benitez, JHEP 1105:081 (2011)). In this work we perform a first-principle quantum field theory calculation of the Kubo formula for the anomalous vortical conductivity and show that it receives contributions proportional to the gravitational anomaly coefficient, inducing a dependence proportional to T² in the vorticity. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid (K. Landsteiner, E. Megias, F. Pena-Benitez, Phys. Rev. Lett. 107, 021601 (2011)).

As a second step of this work, we study an holographic AdS/CFT modelling of the gravitational anomaly by considering a 5-dim Einstein-Maxwell model supplemented with a gauge Chern-Simons and a mixed gauge-gravitational Chern-Simons term. We confirm at strong coupling also the dependence on T² induced by the gravitational anomaly (K. Landsteiner, E. Megias, L. Melgar, F. Pena-Benitez, JHEP 09: 121 (2011)).

12:00-2:00 pm: Lunch

2:00-3:00, Room C520, Physics and Astronomy Tower
Mariano Chernicoff, "The gluonic field of a heavy quark in a strongly coupled CFT"

Abstract: By means of the AdS/CFT correspondence, we determine the gluonic field configuration sourced by a heavy quark undergoing arbitrary motion in N=4 super-Yang-Mills at strong coupling. Our results for this observable show that signals propagate without temporal broadening, just as was found for the expectation value of the energy density in recent work by Hatta et al. We attempt to shed some additional light on the origin of this feature, and propose a different interpretation for its physical significance. As an application of our general results, we examine tr[F²] when the quark undergoes oscillatory motion and uniform circular motion.

3:00-3:30 pm: Coffee and discussion

TUESDAY, NOVEMBER 1

10:00-11:00, Room C520, Physics and Astronomy Tower
Ruben Sandapen, "Holographic wavefunctions and Distribution Amplitudes for the rho meson"

Abstract: In a recent work, we have extracted the light-cone wavefunctions and Distribution Amplitudes (DAs) for the rho meson using the current HERA data on diffractive rho production. We found that the extracted DAs are broader than the asymptotic DA and are consistent with Sum Rules and lattice predictions. We now compare our extracted DAs with those obtained using the AdS/QCD correspondence.

11:00-12:00, Room C520, Physics and Astronomy Tower
Andreas Karch, "An improved model of vector mesons in holographic QCD"

Abstract: We analyze the sector of dimension-three vector meson operators in the "hard wall" model of holographic QCD, including the vector and axial currents, dual to gauge fields in the bulk, and the tensor operator ψ σ ^{μ ν}ψ, dual to a two-form field satisfying a complex self-duality condition. The model includes the effect of chiral symmetry breaking on vector mesons, that involves a coupling between the dual gauge field and the two-form field. We compute the leading logarithmic terms in the operator product expansion of two-point functions and the leading non-perturbative contribution to the tensor-vector correlator. The result is consistent with the operator product expansion of QCD. We also study the spectrum of vector mesons numerically.

12:00-2:00 pm: Lunch

2:00-3:00, Room C520, Physics and Astronomy Tower
Hilmar Forkel, "Hadrons as Holograms"

Abstract: We present an overview of our recent work on strong-interaction physics from the gauge/gravity perspective. In particular, we will discuss (i) a minimal “metric soft wall” AdS/QCD dual which generates linear trajectories of universal slope for both meson and baryon square masses, (ii) a holographic description of diquark correlations in baryons and in the lightest scalar mesons, (iii) an AdS/QCD dual which emerges as a new solution of 5d Einstein-dilaton gravity and realizes area-law confinement and linear meson trajectories dynamically, and finally (iv) the calculation of glueball correlation functions and decay constants, as well as a quantitative analysis of their QCD-related physics content, in both the hard- and dilaton soft-wall AdS/QCD duals.

3:00-3:30 pm: Coffee and discussion

WEDNESDAY, NOVEMBER 2

10:00-11:00, Room C520, Physics and Astronomy Tower
Alex Buchel, "Confinement/deconfinement and csb in gauge theory/string theory correspondence"

Abstract: I will discuss the physics of confinement/deconfinement and chiral symmetry breaking phase transitions of a QCD-like model in the framework of gauge theory/string theory correspondence.

11:00-12:00, Room C520, Physics and Astronomy Tower
Mithat Unsal, "Gauge dynamics, topological molecules and deconfinement"

ABbstract: We study the dynamics of four dimensional gauge theories with adjoint fermions by using circle (non-thermal) and thermal compactification. Circle compactification admits a semi-classical domain where gauge dynamics, both perturbatively and non-perturbatively, is under control. There are new gauge phenomena. We show that, to all orders in perturbation theory, many gauge groups are Higgsed by the gauge holonomy around the circle in the weak-coupling domain. Non-perturbatively, there are monopole-instantons (with fermion zero modes) and two types of monopole--anti-monopole molecules, called bions. The plasma of the type-one bions---which carry net magnetic charge---induces a mass gap for gauge fluctuations. The type-two bion is both topologically and magnetically neutral, and its understanding requires a generalization of multi-instanton techniques in quantum mechanics---which we refer to as the Bogomolny--Zinn-Justin prescription---to compactified field theory. The type-two bions generate a center -stabilizing potential for the gauge holonomy, which is a new topological effect in 4-d gauge theories. If I have enough time at the end, I will switch to the thermal theory and briefly mention the role of center-stabilizing bions in deconfinement phase transition.

12:00-2:00 pm: Lunch

2:00-3:00, Room C520, Physics and Astronomy Tower
Arnab Kundu, "External parameters and chiral symmetry breaking in the holographic dual of large N gauge theories"

Abstract: Using the gauge-gravity duality, more specifically the AdS/CFT correspondence, we will discuss strongly coupled dynamics of fundamental flavours in a large N gauge theory. We will primarily focus on the physics of chiral symmetry breaking by introducing flavour degrees of freedom in the so called Klebanov-Witten model. We will discuss how these fundamental flavours respond to external parameters such as non-zero temperature or an external electro-magnetic field and analyze the corresponding non-trivial phase diagrams. We will briefly comment on the results of similar studies in other holographic models.

3:00-3:30 pm: Coffee and discussion

THURSDAY, NOVEMBER 3

10:00-11:00, Room C520, Physics and Astronomy Tower
Mindaugas Lekaveckas, "Transverse Momentum Broadening in Weakly Coupled Quark-Gluon Plasma"

Abstract: Jet quenching parameter or, equivalently, transverse momentum broadening distribution is an important quantity which helps to understand energy losses in heavy ion collisions and get insights into properties of the de-confined quark-gluon plasma. SCET provides framework to calculate jet quenching parameter at weak coupling using expectation value of two space-like separated light-like Wilson lines which can be evaluated for desired medium. In this work we evaluate transverse momentum broadening distribution for the equilibrium weakly coupled quark-gluon plasma valid in all the momentum region and in the IR limit go beyond Hard Thermal Loop (HTL) approximation.

11:00-12:00, Room C520, Physics and Astronomy Tower
David Mateos, "Thermodynamics and instabilities of a strongly coupled anisotropic plasma"

Abstract: I will present a IIB supergravity solution dual to a spatially anisotropic, finite-temperature, N = 4 super Yang-Mills plasma. I will discuss its thermodynamics and show that the phase diagram exhibits homogeneous and inhomogeneous (i.e. mixed) phases. In some regions the homogeneous phase displays instabilities reminiscent of those of weakly coupled plasmas. I will comment on similarities with QCD at finite baryon density and with the phenomenon of cavitation.

12:00-2:00 pm: Lunch

2:00-3:00, Room C520, Physics and Astronomy Tower
Jinfeng Liao, "Fermion Fluctuations & Correlations in sQGP: Quasi-Particles, or Bound-States, or Holography?"

Abstract: Fermion fluctuations and correlations provide essential information about the microscopic structure of the strongly coupled quark-gluon plasma created in relativistic heavy ion collisions. These properties are closely related to the experimentally measurable quantities and can be evaluated on the lattice via the conserved charge susceptibilities. In this talk I will discuss what we've learned about sQGP from studying the fermion fluctuations & correlations. In particular I will present the results obtained from the holographic QCD model and make comparison with lattice QCD results as well as other models.

3:00-3:30 pm: Coffee and discussion

7:00 pm: Workshop dinner at Bilbao Spanish Restaurant, 4500 9th Ave NE.

FRIDAY, NOVEMBER 4

9:30-10:30, Room C421, Physics and Astronomy Tower
Di-Lun Yang, "Jet Quenching and Holographic Thermalization"

Abstract: We utilize AdS-Vaidya metric which describes a falling mass shell to investigate the thermalization of N=4 super Yang-Mills plasma. In the thin shell limit, the spacetime will be separated into quasi-AdS spacetime inside the shell and AdS-Schwarzschild spacetime outside the shell, which correspond to the regimes before and after the thermalization respectively. We then compute the stopping distance of a massless particle traveling through AdS-Vaidya spacetime, which is greater than the result found in the thermalized medium. Finally, a smaller value of the approximate jet quenching parameter can be derived by analyzing a moving string bounded by the null geodesic trajectory in this scenario.

10:30-11:30, Room C421, Physics and Astronomy Tower
Oleg Andreev, "Some Comments on Relativistic Hydrodynamics, Fuzzy Bag Models for the Pressure, and Early Space-Time Evolution of the QCD Matter"

Abstract: I discuss three subjects: the relativistic hydrodynamics equations for a boost-invariant expanding fluid; the fuzzy bag model for the pressure which recently appeared in QCD phenomenology; and the early space-time evolution of the QCD matter, drawn from model studies, which can also be expected to arise in realistic fluid dynamics relevant to heavy ion collisions at LHC.

11:30-12:30, Room C421, Physics and Astronomy Tower
Diana Vaman "Jet quenching revisited and simplified via AdS/CFT"

Abstract: The evolution of a highly energetic jet in the strongly coupled N=4 superYang-Mills plasma can be described via 3-point real-time finite temperature correlators, which I will compute using AdS/CFT. The result is that typical jet stopping distance scales with energy as E^1/4, while the maximal stopping distance scales as E^1/3. I will then show how these scales can be also derived from the perspective of 5-d point-particles following geodesic trajectories in the black hole geometry. I will conclude with a study of 4-point correlators to determine whether the jet deposits its charge over a wide or narrow spatial range.

12:30 pm: Lunch