Mariano Chernicoff

The energy of a moving quark-antiquark pair in an Script N = 4 SYM plasma

We make use of the AdS/CFT correspondence to determine the energy of an external quark-antiquark pair that moves through strongly-coupled thermal = 4 super-Yang-Mills plasma, both in the rest frame of the plasma and in the rest frame of the pair. It is found that the pair feels no drag force, has an energy that reproduces the expected 1/L (or γ/L) behavior at small quark-antiquark separations, and becomes unbound beyond a certain screening length whose velocity-dependence we determine. We discuss the relation between the high-velocity limit of our results and the lightlike Wilson loop proposed recently as a definition of the jet-quenching parameter.

Acceleration, energy loss and screening in strongly-coupled gauge theories

We explore various aspects of the motion of heavy quarks in strongly-coupled gauge theories, employing the AdS/CFT correspondence. Building on earlier work by Mikhailov, we study the dispersion relation and energy loss of an accelerating finite-mass quark in = 4 super-Yang-Mills, both in vacuum and in the presence of a thermal plasma. In the former case, we notice that the application of an external force modifies the dispersion relation. In the latter case, we find in particular that when a static heavy quark is accelerated by an external force, its rate of energy loss is initially insensitive to the plasma, and there is a delay before this rate approaches the value derived previously from the analysis of stationary or late-time configurations. Following up on work by Herzog et al., we also consider the evolution of a quark and antiquark as they separate from one another after formation, learning how the AdS/CFT setup distinguishes between the singlet and adjoint configurations, and locating the transition to the stage where the deceleration of each particle is properly accounted for by a constant friction coefficient. Additionally, we examine the way in which the energy of a quark-antiquark pair moving jointly through the plasma scales with the quark mass. We find that the velocity-dependence of the screening length is drastically modified in the ultra-relativistic region, and is comparable with that of the transition distance mentioned above.

Drag force in a strongly coupled anisotropic plasma

A bstractWe calculate the drag force experienced by an infinitely massive quark propagating at constant velocity through an anisotropic, strongly coupled

Quantum Fluctuations and the Unruh effect in strongly-coupled conformal field theories

\mathcal{N} = 4

Energy loss of gluons, baryons and k-quarks in an = 4 SYM plasma

plasma by means of its gravity dual. We find that the gluon cloud trailing behind the quark is generally misaligned with the quark velocity, and that the latter is also misaligned with the force. The drag coefficient μ can be larger or smaller than the corresponding isotropic value depending on the velocity and the direction of motion. In the ultra-relativistic limit we find that generically μ ∝ p. We discuss the conditions under which this behaviour may extend to more general situations.

Holographic lessons for quark dynamics

Through the AdS/CFT correspondence, we study a uniformly accelerated quark in the vacuum of strongly-coupled conformal field theories in various dimensions, and determine the resulting stochastic fluctuations of the quark trajectory. From the perspective of an inertial observer, these are quantum fluctuations induced by the gluonic radiation emitted by the accelerated quark. From the point of view of the quark itself, they originate from the thermal medium predicted by the Unruh effect. We scrutinize the relation between these two descriptions in the gravity side of the correspondence, and show in particular that upon transforming the conformal field theory from Rindler space to the open Einstein universe, the acceleration horizon disappears from the boundary theory but is preserved in the bulk. This transformation allows us to directly connect our calculation of radiation-induced fluctuations in vacuum with the analysis by de Boer et al. of the Brownian motion of a quark that is on average static within a thermal medium. Combining this same bulk transformation with previous results of Emparan, we are also able to compute the stress-energy tensor of the Unruh thermal medium.

Jet quenching in a strongly coupled anisotropic plasma

We consider different types of external color sources that move through a strongly-coupled thermal N = 4 super-Yang-Mills plasma, and calculate, via the AdS/CFT correspondence, the dissipative force (or equivalently, the rate of energy loss) they experi- ence. A bound state of k quarks in the totally antisymmetric representation is found to feel a force with a nontrivial k-dependence. Our result for k=1 (or k = N i 1) agrees at large N with the one obtained recently by Herzog et al. and Gubser, but contains in addition an infinite series of 1/N corrections. The baryon (k = N) is seen to experience no drag. Finally, a heavy gluon is found to be subject to a force which at large N is twice as large as the one experienced by a heavy quark, in accordance with gauge theory expectations.

Quarkonium dissociation by anisotropy

We give a brief overview of recent results obtained through the gauge/gravity correspondence, concerning the propagation of a heavy quark in strongly-coupled conformal field theories (such as N = 4 super-Yang-Mills), both at zero and finite temperature. In the vacuum, we discuss energy loss, radiation damping, signal propagation and radiation-induced fluctuations. In the presence of a thermal plasma, our emphasis is on early-time energy loss, screening and quark-antiquark evolution after pair creation. Throughout, quark dynamics is seen to be efficiently encapsulated in the usual string worldsheet dynamics.

Holographic EPR pairs, wormholes and radiation

A bstractThe jet quenching parameter of an anisotropic plasma depends on the relative orientation between the anisotropic direction, the direction of motion of the parton, and the direction along which the momentum broadening is measured. We calculate the jet quenching parameter of an anisotropic, strongly coupled

The gluonic field of a heavy quark in conformal field theories at strong coupling

\mathcal{N} = 4