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Search Results: 1 - 10 of 2569 matches for " Mariano Chernicoff "
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Accelerated detectors and worldsheet horizons in AdS/CFT
Mariano Chernicoff,Angel Paredes
Physics , 2010, DOI: 10.1007/JHEP03(2011)063
Abstract: We use the AdS/CFT correspondence to discuss the response of an accelerated observer to the quantum vacuum fluctuations. In particular, we study heavy quarks probing a strongly coupled CFT by analysing strings moving in AdS. We propose that, in this context, a non-trivial detection rate is associated to the existence of a worldsheet horizon and we find an Unruh-like expression for the worldsheet temperature. Finally, by examining a rotating string in global AdS we find that there is a transition between string embeddings with and without worldsheet horizon. The dual picture corresponds to having non-trivial or trivial interaction with the quantum vacuum respectively. This is in qualitative agreement with results of Davies et al.
Generalized Lorentz-Dirac Equation for a Strongly-Coupled Gauge Theory
Mariano Chernicoff,J. Antonio Garcia,Alberto Guijosa
Physics , 2009, DOI: 10.1103/PhysRevLett.102.241601
Abstract: We derive a semiclassical equation of motion for a `composite' quark in strongly-coupled large-N_c N=4 super-Yang-Mills, making use of the AdS/CFT correspondence. The resulting non-linear equation incorporates radiation damping, and reduces to the standard Lorentz-Dirac equation for external forces that are small on the scale of the quark Compton wavelength, but has no self-accelerating or pre-accelerating solutions. From this equation one can read off a non-standard dispersion relation for the quark, as well as a Lorentz covariant formula for its radiation rate.
Quantum Fluctuations and the Unruh Effect in Strongly-Coupled Conformal Field Theories
Elena Caceres,Mariano Chernicoff,Alberto Guijosa,Juan F. Pedraza
Physics , 2010, DOI: 10.1007/JHEP06(2010)078
Abstract: 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
Mariano Chernicoff,Daniel Fernandez,David Mateos,Diego Trancanelli
Physics , 2012, DOI: 10.1007/JHEP08(2012)041
Abstract: The 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 N=4 plasma by means of its gravity dual. We present the results for arbitrary orientations and arbitrary values of the anisotropy. The anisotropic value 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. We compare our results to analogous calculations for the real-world quark-gluon plasma and find agreement in some cases and disagreement in others.
Drag force in a strongly coupled anisotropic plasma
Mariano Chernicoff,Daniel Fernandez,David Mateos,Diego Trancanelli
Physics , 2012, DOI: 10.1007/JHEP08(2012)100
Abstract: We calculate the drag force experienced by an infinitely massive quark propagating at constant velocity through an anisotropic, strongly coupled N=4 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 $\mu$ 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 $\mu \propto p$. We discuss the conditions under which this behaviour may extend to more general situations.
Quarkonium dissociation by anisotropy
Mariano Chernicoff,Daniel Fernandez,David Mateos,Diego Trancanelli
Physics , 2012, DOI: 10.1007/JHEP01(2013)170
Abstract: 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.
El basamento de la sierra de San Luis: Nuevas evidencias magnéticas y sus implicancias tectónicas The basement of Sierra de San Luis: New magnetic evidence and tectonic implication
CJ Chernicoff,VA Ramos
Revista de la Asociación Geológica Argentina , 2003,
Abstract: Los mapas aeromagnéticos disponibles de las sierras de San Luis y Comechingones en el sector sudoriental de las Sierras Pampeanas de Argentina, permiten examinar las características geológicas y estructurales de las unidades metamórficas e intrusivas del basamento de la región. A través de la aplicación del filtro de continuación ascendente a los datos del campo magnético total reducido al polo, se ha podido observar la configuración profunda de las distintas unidades. Entre ellas se destaca la secuencia supracortical, en parte correspondiente a la Formación San Luis, que permite reconstruir en varios sectores de la región, en algunos casos subaflorante, una importante sucesión de rocas metasedimentarias de hasta 3 km de espesor, que es interpretada como perteneciente a depósitos de una cuenca de antepaís formada con posterioridad a la orogenia pampeana, alrededor de los 530 Ma. Se caracterizan las distintas unidades metamórficas e ígneas a partir de su se al magnética, y sobre esta base se presenta una sección estructural profunda, que sirve de base para proponer la evolución tectónica del basamento de este sector de las Sierras Pampeanas. éste registra a partir de la orogenia pampeana la instalación de un arco magmático con su respectiva cuenca de trasarco durante el Cámbrico tardío y el Ordovícico temprano, los que son cerrados y deformados durante la colisión del terreno de Cuyania en el Ordovícico medio. The available aeromagnetic maps of the Sierras de San Luis and Comechingones in the south-eastern sector of the Sierras Pampeanas of Argentina, show the geologic and structural characteristics of the metamorphic and intrusive units of the basement of the region. Through the upward continuation filter applied to the magnetic data, it is possible to view the depth to the different units. Among them it stands out the supracrustal sequence partly equivalent to the San Luis Formation, interpreted as foreland basin deposits formed at about 530 Ma as a consequence of the Pampean orogeny; this important succession of metasedimentary rocks, recognized in several sectors, some of them overlain by a thin cover of Cenozoic sediments, reaches a thickness of as much as 3km. The other metamorphic and igneous units are characterized based on their magnetic properties, and on these bases a deep structural section of the basement is produced, that allow to propose a tectonic model for the evolution of the region. The area after the Pampean orogeny recorded the inception of a magmatic arc and an associated back-arc basin during the late Cambrian and early Ordovician,
Delimitación de los terrenos tectonoestratigráficos de la región centro-austral Argentina: evidencias aeromagnéticas
Chernicoff,Carlos J.; Zappettini,Eduardo O.;
Revista geológica de Chile , 2003, DOI: 10.4067/S0716-02082003000200009
Abstract: delimitation of tectonostratigraphic terranes of the southern-central region of argentina: aeromagnetic evidences. the geological interpretation of the high-resolution aeromagnetic data of the la pampa province, in addition to the low-density magnetic information from the region of the neuquina and colorado basins, leads to define the precise boundaries of the chilenia, cuyania, pampia and patagonia terranes, and the río de la plata craton within the study region. the data from the high-resolution. aeromagnetic survey, in particular, are compared and studied in conjunction with all the available geological information. this results in a map of the solid geology of this region largely covered by quaternary sediments, in which eleven pre-cenozoic and two-cenozoic lithomagnetic units are represented. a number of structures of different magnitudes, as well as their relative chronology, are also recognized, i.e., regional faulting, sub-regional faulting/fracturing/shearing and the most conspicuous magnetic fabric of the basement which reflects its main planar structures. three different basements are distinguished on the basis of their contrasting magnetic character, and are interpreted to integrate the cuyania and pampia terranes and the río de la plata craton, separated from each other by large-scale discontinuities. in the western part of the study region an additional master discontinuity separates the chilenia and cuyania terranes. in the southernmost area, wnw-trending structures are predominant, particularly a master nne-vergent thrust that indicates the truncation of the cuyana-pampia suture and is regarded to be related to the collision of the patagonia terrane. an east-west - trending, convex to the north, arch-shaped regional magnetic high and an equally shaped positive residual bouguer anomaly located immediately to the south of 39°s, whose activation, during the mesozoic gave rise to the huincul dorsal, indicate the interruption of the distinct submeridional
Delimitación de los terrenos tectonoestratigráficos de la región centro-austral Argentina: evidencias aeromagnéticas
Carlos J. Chernicoff,Eduardo O. Zappettini
Revista geológica de Chile , 2003,
Abstract: La interpretación de datos aeromagnéticos de alta resolución en la Provincia de La Pampa sumados a información magnética de baja densidad en los ámbitos de las Cuencas Neuquina y del Colorado, permiten precisar los límites de los terrenos Chilenia, Cuyania, Pampia y Patagonia, y del Cratón del Río de la Plata en la región analizada. En particular, los datos aeromagnéticos de alta resolución son contrastados con la información geológica disponible y se discriminan así once unidades litomagnéticas pre-cenozoicas y dos cenozoicas, representadas en un mapa de geología sólida de esta región ampliamente cubierta por sedimentos cuaternarios. Asimismo se identifican estructuras de diverso orden y su cronología relativa: fallas de carácter regional de primer orden; fallas, fracturas y zonas de cizalla de carácter subregional, así como la fábrica magnética más conspicua del basamento que refleja sus principales estructuras planares. Se diferencian tres unidades de características magnéticas contrastantes en el basamento interpretados como integrantes de los terrenos tectonoestratigráficos Cuyania y Pampia y del Cratón del Río de la Plata, separados por discontinuidades de primer orden. Una discontinuidad del mismo tipo separa a los terrenos Chilenia y Cuyania, en el sector occidental de la zona de estudio. En el extremo sur del área investigada se hacen dominantes las estructuras de rumbo WNW, en particular un corrimiento mayor, de vergencia NNE, que marca el truncamiento austral de la sutura Cuyania-Pampia. Un máximo regional magnético y una anomalía residual de Bouguer positiva, dispuestos conformando un arco de orientación este-oeste convexo hacia el norte y localizados inmediatamente al sur de los 39°S, se alan la interrupción de la estructuración submeridional de los terrenos Chilenia, Cuyania y Pampia al norte de los mismos; representarían la zona de sutura entre el terreno Patagonia y Gondwana, cuya activación durante el Mesozoico dio lugar a la Dorsal de Huincul Delimitation of tectonostratigraphic terranes of the southern-central region of Argentina: aeromagnetic evidences. The geological interpretation of the high-resolution aeromagnetic data of the La Pampa province, in addition to the low-density magnetic information from the region of the Neuquina and Colorado basins, leads to define the precise boundaries of the Chilenia, Cuyania, Pampia and Patagonia terranes, and the Río de la Plata Craton within the study region. The data from the high-resolution. aeromagnetic survey, in particular, are compared and studied in conjunction with all the available ge
Localización de centros eruptivos mediante areomagnetometría en el sector central del Valle del Cura, San Juan, Argentina: implicancias para la evolución del arco/retroarco cenozoico
Litvak,Vanesa D; Chernicoff,Carlos J; Poma,Stella M;
Revista geológica de Chile , 2005, DOI: 10.4067/S0716-02082005000100005
Abstract: a solid geology map was prepared for the study region, based on the aeromagnetic survey and geological mapping of the region. the geological-structural analysis of the aeromagnetic survey has identified circular features interpreted as anular fractures associated with eruptive centres. the brea eruptive centre is of shallow nature; there is no evidence of the occurrence of an associated subvolcanic body; it is located in a structurally favourable setting characterized by the intersection of a submeridional thrust and a system of ne-trending fractures; its age is assigned to the eocene and it is located in a back-arc setting, considering the location of the contemporaneous volcanic-arc deposits. the zancarrón eruptive centre is regarded as a volcanic caldera, an observation which is consistent with the geological evidences of the presence of a miocene strato-volcano in this region. there is geophysical evidence that indicates oligocene volcanic rocks underlying the core of the eruptive centre, which suggests that its magmatic activity would have started during the oligocene; in this case, the zancarrón eruptive centre would represent an additional centre of the do?a ana group (oligocene) similar to the one recognized within the chilean territory. based on the association of this group with mineralised hydrothermal alteration zones within the valle del cura region, the possible identification of covered oligocene volcanic rocks may be of a special interest for mining exploration
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