We carry out a systematic study of the effective bosonic string describing confining flux tubes in SU(N) Yang-Mills theories in three spacetime dimensions. While their low-energy properties are known to be universal and are described well by the Nambu-Gotō action, a non-trivial dependence on the gauge group is encoded in a series of undetermined subleading corrections in an expansion around the limit of an arbitrarily long string. We quantify the first two of these corrections by means of high-precision Monte Carlo simulations of Polyakov-loop correlators in the lattice regularization. We compare the results of novel lattice simulations for theories with N = 3 and 6 color charges, and report an improved estimate for the N = 2 case, discussing the approach to the large-N limit. Our results are compatible with analytical bounds derived from the S-matrix bootstrap approach. In addition, we also present a new test of the Svetitsky-Yaffe conjecture for the SU(3) theory in three dimensions, finding that the lattice results for the Polyakov-loop correlation function are in excellent agreement with the predictions of the Svetitsky-Yaffe mapping, which are worked out quantitatively applying conformal perturbation theory to the three-state Potts model in two dimensions. The implications of these results are discussed.

Italy

Michele Caselle

Nicodemo Magnoli

Alessandro Nada

Marco Panero

Dario Panfalone

Lorenzo Verzichelli

Confining strings in three-dimensional gauge theories beyond the Nambu-Gotō approximation

In this paper we study the dynamical properties of charged systems immersed in an external magnetic field and perturbed by a set of scalar operators breaking translations either spontaneously or pseudo-spontaneously. By combining hydrodynamic and quantum field theory arguments we provide analytic expressions for all the hydrodynamic transport coefficients relevant for the diffusive regime in terms of thermodynamic quantities and DC thermo-electric conductivities. This includes the momentum dissipation rate. We shed light on the role of the momentum dissipation rate in the transition between the pseudo-spontaneous and the purely explicit regimes in this class of systems. Finally, we clarify several relations between the hydrodynamic transport coefficients which have been observed in the holographic literature of charge density wave models.

Andrea Amoretti

Spain

Daniel Areán

Daniel Brattan

Hydrodynamic magneto-transport in charge density wave states

In this paper we have considered the 3D Ising model perturbed with the energy operator coupled with a nonuniform harmonic potential acting as a trap, showing that this system satisfies the trap-size scaling behavior. Eventually, we have computed the correlators <math><mo>⟨</mo><mi>σ</mi><mo>(</mo><mi>z</mi><mo>)</mo><mi>σ</mi><mo>(</mo><mn>0</mn><mo>)</mo><mo>⟩</mo></math>, <math><mo>⟨</mo><mi>ε</mi><mo>(</mo><mi>z</mi><mo>)</mo><mi>ε</mi><mo>(</mo><mn>0</mn><mo>)</mo><mo>⟩</mo></math> and <math><mo>⟨</mo><mi>σ</mi><mo>(</mo><mi>z</mi><mo>)</mo><mi>ε</mi><mo>(</mo><mn>0</mn><mo>)</mo><mo>⟩</mo></math> near the critical point by means of conformal perturbation theory. Combining this result with Monte Carlo simulations, we have been able to estimate the OPE coefficients <math><msubsup><mi>C</mi><mrow><mi>σ</mi><mi>ε</mi></mrow><mi>σ</mi></msubsup></math>, <math><msubsup><mi>C</mi><mrow><mi>σ</mi><mi>σ</mi></mrow><mi>ε</mi></msubsup></math> and <math><msubsup><mi>C</mi><mrow><mi>ε</mi><mi>ε</mi></mrow><mi>ε</mi></msubsup></math>, finding a good agreement with the values obtained in [G. Costagliola, Phys. Rev. D 93, 066008 (2016), F. Kos, D. Poland, D. Simmons-Duffin, and A. Vichi, J. High Energy Phys. 08 (2016) 036].

Switzerland

Gianluca Costagliola

Marcello Scanavino

Energy trapped Ising model

We consider magnetohydrodynamics with an external magnetic field. We find that in general one must allow for a non-zero incoherent Hall conductivity to correctly describe the DC longitudinal and Hall thermal conductivities beyond order zero in the magnetic field expansion. We apply our result to the dyonic black hole, determining the incoherent Hall conductivity in that case, and additionally prove that the existence of this transport coefficient leads to a significantly better match between the hydrodynamic and AC thermo-electric correlators.

Magneto-thermal transport implies an incoherent Hall conductivity

We study the accuracy and predictive power of conformal perturbation theory by a comparison with lattice results in the neighborhood of the finite-temperature deconfinement transition of SU(2) Yang-Mills theory, assuming that the infrared properties of this non-Abelian gauge theory near criticality can be described by the Ising model. The results of this comparison show that conformal perturbation theory yields quantitatively accurate predictions in a broad temperature range. We discuss the implications of these findings for the description of the critical point (belonging to the same universality class) of another strongly coupled, nonsupersymmetric non-Abelian gauge theory: the critical end point in the phase diagram of QCD at finite temperature and finite quark chemical potential.

Germany

Conformal perturbation theory confronts lattice results in the vicinity of a critical point

Magnetic field and momentum dissipation are key ingredients in describing condensed matter systems. We include them in gauge/gravity and systematically explore the bottom-up panorama of holographic IR effective field theories based on bulk EinsteinMaxwell Lagrangians plus scalars. The class of solutions here examined appears insufficient to capture the phenomenology of charge transport in the cuprates. We analyze in particular the temperature scaling of the resistivity and of the Hall angle. Keeping an open attitude, we illustrate weak and strong points of the approach.

United Kingdom

Matteo Baggioli

Daniele Musso

Chasing the cuprates with dilatonic dyons

Inspired by a recently conjectured universal bound for thermo-electric diffusion constants in quantum critical, strongly coupled systems and relying on holographic analytical computations, we investigate the possibility of formulating Planckian bounds in different holographic models featuring momentum dissipation. For a certain family of solutions to a simple massive gravity dilaton model at zero charge density we find linear in temperature resistivity and entropy density alongside a constant electric susceptibility. In addition we explicitly find that the sum of the thermo-electric diffusion constants is bounded.

Netherlands

Alessandro Braggio

Bounds on charge and heat diffusivities in momentum dissipating holography

We present a systematic definition and analysis of the thermo-electric linear response in gauge/gravity systems focusing especially on models with massive gravity in the bulk and therefore momentum dissipation in the dual field theory. A precise treatment of finite counter-terms proves to be essential to yield a consistent physical picture whose hydrodynamic and beyond-hydrodynamics behaviors noticeably match with field theoretical expectations. The model furnishes a possible gauge/gravity description of the crossover from the quantum-critical to the disorder-dominated Fermi-liquid behaviors, as expected in graphene.

Nicola Maggiore

Thermo-electric transport in gauge/gravity models with momentum dissipation

We consider a free topological model in 5D Euclidean flat spacetime, built from two rank-2 tensor fields. Despite the fact that the bulk of the model does not have any particular physical interpretation, on its 4D planar edge nontrivial gauge field theories are recovered, whose features descend from the gauge and discrete symmetries of the bulk. In particular the 4D dynamics cannot be obtained without imposing a Time Reversal invariance in the bulk. Remarkably, one of the two possible edge models selected by the Time Reversal symmetries displays a true electromagnetic duality, which relates strong and weak coupling regimes. Moreover the same model, when considered on-shell , coincides with the Maxwell theory, which therefore can be thought of as a 4D boundary theory of a seemingly harmless 5D topological model.

Giacomo Caruso

Holography in flat spacetime: 4D theories and electromagnetic duality on the border

We consider the fermionization of a bosonic-free theory characterized by the <math id="M2"><mn>3</mn><mo>+</mo><mn>1</mn><mi>D</mi></math> scalar-tensor duality. This duality can be interpreted as the dimensional reduction, via a planar boundary, of the <math id="M3"><mn>4</mn><mo>+</mo><mn>1</mn><mi>D</mi></math> topological BF theory. In this model, adopting the Sommerfield tomographic representation of quantized bosonic fields, we explicitly build a fermionic operator and its associated Klein factor such that it satisfies the correct anticommutation relations. Interestingly, we demonstrate that this operator satisfies the massless Dirac equation and that it can be identified with a <math id="M4"><mn>3</mn><mo>+</mo><mn>1</mn><mi>D</mi></math> Weyl spinor. Finally, as an explicit example, we write the integrated charge density in terms of the tomographic transformed bosonic degrees of freedom.