Screening length and the direction of plasma winds

We study the screening length of a heavy quark-antiquark pair in strongly coupled gauge theory plasmas flowing at velocity v following a proposal by Liu, Rajagopal, and Wiedemann. We analyze the screening length as the direction of the plasma winds vary. To leading order in v, this angle-dependence can be studied analytically for many theories by extending our previous formalism. We show that the screening length is locally a minimum (maximum) when the pair is perpendicular (parallel) to the plasma winds, which has been observed for the N=4 plasma. Also, we compare AdS/CFT results with weak coupling ones, and we discuss the subleading dependence on v for the Dp-brane.Comment: 20 pages, 4 figures, JHEP3; v2: discussion added and modifie

Heavy quarks in a magnetic field

The motion of a heavy charged quark in a magnetic field is analyzed in the vacuum of strongly coupled CFT. The motion of the quark is dissipative. It moves in spiral until it eventually comes to rest. The world-sheet geometry is locally AdS_2 but has a time dependent horizon. The string profile in the static gauge extends from the boundary till a point where an embedding singularity exists. Connections with other circular string motions are established.Comment: (v3) Misprints corrected, discussion on moving horizons improved and enhance

Back reaction effects on the dynamics of heavy probes in heavy quark cloud

We holographically study the effect of back reaction on the hydrodynamical properties of $\mathcal{N} = 4$ strongly coupled super Yang-Mills (SYM) thermal plasma. The back reaction we consider arises from the presence of static heavy quarks uniformly distributed over $\mathcal{N} = 4$ SYM plasma. In order to study the hydrodynamical properties, we use heavy quark as well as heavy quark-antiquark bound state as probes and compute the jet quenching parameter, screening length and binding energy. We also consider the rotational dynamics of heavy probe quark in the back-reacted plasma and analyse associated energy loss. We observe that the presence of back reaction enhances the energy-loss in the thermal plasma. Finally, we show that there is no effect of angular drag on the rotational motion of quark-antiquark bound state probing the back reacted thermal plasma.Comment: 29 pages, 21 figure

On the Beaming of Gluonic Fields at Strong Coupling

We examine the conditions for beaming of the gluonic field sourced by a heavy quark in strongly-coupled conformal field theories, using the AdS/CFT correspondence. Previous works have found that, contrary to naive expectations, it is possible to set up collimated beams of gluonic radiation despite the strong coupling. We show that, on the gravity side of the correspondence, this follows directly (for arbitrary quark motion, and independently of any approximations) from the fact that the string dual to the quark remains unexpectedly close to the AdS boundary whenever the quark moves ultra-relativistically. We also work out the validity conditions for a related approximation scheme that proposed to explain the beaming effect though the formation of shock waves in the bulk fields emitted by the string. We find that these conditions are fulfilled in the case of ultra-relativistic uniform circular motion that motivated the proposal, but unfortunately do not hold for much more general quark trajectories.Comment: 1+33 pages, 2 figure

Energy loss in a strongly coupled anisotropic plasma

We study the energy loss of a rotating infinitely massive quark moving, at constant velocity, through an anisotropic strongly-coupled N=4 plasma from holography. It is shown that, similar to the isotropic plasma, the energy loss of the rotating quark is due to either the drag force or radiation with a continuous crossover from drag-dominated regime to the radiation dominated regime. We find that the anisotropy has a significant effect on the energy loss of the heavy quark, specially in the crossover regime. We argue that the energy loss due to radiation in anisotropic media is less than the isotropic case. Interestingly this is similar to analogous calculations for the energy loss in weakly coupled anisotropic plasma.Comment: 26+1 pages, 10 figures, typos fixe

Stability of strings binding heavy-quark mesons

We investigate the stability against small deformations of strings dangling into AdS_5-Schwarzschild from a moving heavy quark-anti-quark pair. We speculate that emission of massive string states may be an important part of the evolution of certain unstable configurations.Comment: 14 pages, 4 figure

The Gluonic Field of a Heavy Quark in Conformal Field Theories at Strong Coupling

We determine the gluonic field configuration sourced by a heavy quark undergoing arbitrary motion in N=4 super-Yang-Mills at strong coupling and large number of colors. More specifically, we compute the expectation value of the operator tr[F^2+...] in the presence of such a quark, by means of the AdS/CFT correspondence. 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 when the quark undergoes oscillatory motion, uniform circular motion, and uniform acceleration. Via the AdS/CFT correspondence, all of our results are pertinent to any conformal field theory in 3+1 dimensions with a dual gravity formulation.Comment: 1+38 pages, 16 eps figures; v2: completed affiliation; v3: corrected typo, version to appear in JHE

Quarkonium dissociation by anisotropy

We compute the screening length for quarkonium mesons moving through an anisotropic, strongly coupled N=4 super Yang-Mills plasma by means of its gravity dual. We present the results for arbitrary velocities and orientations of the mesons, as well as for arbitrary values of the anisotropy. The anisotropic screening length can be larger or smaller than the isotropic one, and this depends on whether the comparison is made at equal temperatures or at equal entropy densities. For generic motion we find that: (i) mesons dissociate above a certain critical value of the anisotropy, even at zero temperature; (ii) there is a limiting velocity for mesons in the plasma, even at zero temperature; (iii) in the ultra-relativistic limit the screening length scales as $(1-v^2)^\epsilon$ with \epsilon =1/2, in contrast with the isotropic result \epsilon =1/4.Comment: 39 pages, 26 figures; v2: minor changes, added reference

Hoja Geológica 3766-IV, General Acha, Provincia de La Pampa

La Hoja Geológica 3766‐IV General Acha se ubica en el centro‐sur de la provincia de La Pampa, entre los paralelos de 37º00’ y 38º00’ de latitud sur y los meridianos de 64º30’ y 66º00’ de longitud oeste. Incluye parcialmente los departamentos de Utracán, Lihuel Calel y Curacó, cubriendo un área aproximada de 14437,25 km2, siendo la ciudad de General Acha el único centro. En el extremo sudoccidental, las sierras de Lihué Calel y Chica constituyen las mayores alturas alcanzando una cota máxima de 600m, mientras que el resto de la Hoja General Acha presenta el aspecto de una planicie ondulada y de suave gradiente hacia el este. En el sector oriental hay depresiones de dirección aproximada SSO‐NNE, conocidos como valles transversales. El río Chadileuvú, denominado Salado en este tramo de su recorrido y que cruza el ángulo sudoeste de la Hoja, representa el único curso de agua permanente. La mayor parte de la superficie cubierta por la Hoja General Acha está conformada por afloramientos de sedimentos neógenos y cuaternarios, entre los cuales asoman saltuariamente elementos que conforman el basamento ígneo‐metamórfico de La Pampa, que constituyen las rocas más antiguas de la comarca que incluye rocas de edades pampeanas y famatinianas. Es por ello que mediante la aplicación de métodos geofísicos y a partir del estudio de los limitados afloramientos existentes se pudieron delimitar en forma precisa que el subsuelo del área cubierta por la Hoja General Acha comprende las porciones meridionales de los terrenos Cuyania y Pampia, amalgamados al margen occidental de Gondwana durante el Paleozoico, y el Cratón del Río de la Plata. El terreno Pampia comprende metasedimentitas neoproterozoicas y cambro‐ordovícicas, aflorantes y subaflorantes, que constituyen la caja del sistema arco‐retroarco famatiniano en la provincia de La Pampa, allí se han diferenciado los Esquistos Santa Helena que comprenden metasedimentitas neoproterozoicas y la Formación Las Piedras que corresponden a metasedimentitas cámbricas. El magmatismo cámbrico está representado por el Complejo Ígneo El Carancho que constituye los afloramientos más australes del arco desarrollado en el margen activo de Pampia. Del lado oriental de la sutura Cuyania‐Pampia (sector SO de la Hoja) ha sido reconocida una faja submeridiana de rocas metaígneas ordovícicas, cuyas características geoquímicas, edad y petrología de sus protolitos ígneos permitieron interpretarlas como el segmento austral del arco magmático famatiniano, siendo formalmente designadas como Formación Paso del Bote. Unas pocas decenas de kilómetros hacia el este del arco famatiniano, también yaciendo en el terreno Pampia, ha sido identificada una faja submeridiana de metagabros ordovícicos metamorfizados en facies anfibolita y esquistos verdes, desginadas Formación Valle Daza e interpretadas como parte del retroarco magmático famatiniano, de incipiente desarrollo en esta región. El desarrollo del Orógeno Famatiniano a lo largo de la sutura Cuyania‐Pampia, dio lugar en la región centro austral argentina, al depósito de sedimentos de antepaís de edad ordovícica superior‐devónica inferior representados por la Formación La Horqueta. Con la acreción de Chilenia al margen occidental de Gondwana con los movimientos chánicos se asocia un magmatismo de tipo postorogénico representado por granitoides que constituyen la Formación Curacó, estos movimientos asimismo reactivaron fallas preexistentes y condujeron a la formación de depocentros más o menos aislados, de los cuales el principal en la región de estudio es el identificado como depocentro Arizona el que es ocupado por la formación homónima, y sería parte de la cuenca de Paganzo.Fil: Silva Nieto, Diego Gonzalo. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; ArgentinaFil: Espejo, Patricia M.. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; ArgentinaFil: Chernicoff, Carlos Jorge. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zappettini, Eduardo Osvaldo. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; Argentin

Moving Defects in AdS/CFT

We study defects of various dimensions moving through Anti-de Sitter space. Using the AdS/CFT correspondence this allows us to probe aspects of the dual quantum field theory. We focus on the energy loss experienced by these defects as they move through the CFT plasma. We find that the behavior of these physical quantities is governed by induced world-volume horizons. We identify world-volume analogs for several gravitational phenomena including black holes, the Hawking-Page phase transition and expanding cosmological horizons.Comment: 24 pages, 7 figures. Version 2 contains two added reference