The Brown-York mass of black holes in Warped Anti-de Sitter space

We give a direct computation of the mass of black holes in Warped Anti-de Sitter space (WAdS) in terms of the Brown-York stress-tensor at the boundary. This permits to explore to what extent the holographic renormalization techniques can be applied to such type of deformation of AdS. We show that, despite some components of the boundary stress-tensor diverge and resist to be regularized by the introduction of local counterterms, the precise combination that gives the quasilocal energy density yields a finite integral. The result turns out to be in agreement with previous computations of the black hole mass obtained with different approaches. This is seen to happen both in the case of Topologically Massive Gravity and of the so-called New Massive Gravity. Here, we focus our attention on the latter. We observe that, despite other conserved charges diverge in the near boundary limit, the finite part in the large radius expansion captures the physically relevant contribution. We compute the black hole angular momentum in this way and we obtain a result that is in perfect agreement with previous calculations.Comment: 8 pages. v2 discussion and appendix added, references added. To appear in JHE

Interacting strings on AdS_3

We consider string theory on AdS_3 in terms of the Wakimoto free field representation. The scattering amplitudes for N unitary tachyons are analysed in the factorization limit and the poles corresponding to the mass-shell conditions for physical states are extracted. The vertex operators for excited levels are obtained from the residues and their properties are examined. Negative norm states are found at the second mass level.Comment: 24 pages, 2 figures, LaTeX. Substantial changes: ghosts found, conclusions modified accordingly, references added. Final version to appear in JHE

Prelogarithmic operators and Jordan blocks in SL(2)_k affine algebra

The free field description of logarithmic and prelogarithmic operators in non compact Wess-Zumino-Witten model is analysed. We study the structure of the Jordan blocks of the SL(2)_k affine algebra and the role of the puncture operator in the theory in relation with the unitarity bound.Comment: 16 pages. Corrected some typos, references and comments adde

Three-point function in perturbed Liouville gravity

Three-point correlation function in perturbed conformal field theory coupled to two-dimensional quantum gravity (perturbed Liouville gravity) is explicitly computed by using the free field approach. The representation considered here is the one recently proposed in [G. Giribet, Nucl. Phys. B 737 (2006) 209] to describe the string theory in AdS3 space. Consequently, this computation extends previous results which presented free field calculations of particular cases of string amplitudes, and confirms that the free field approach leads to the exact result. Remarkably, this representation allows to compute winding violating three-point functions without making use of the spectral flow operator.Facultad de Ciencias Exacta

Three-point function in perturbed Liouville gravity

Three-point correlation function in perturbed conformal field theory coupled to two-dimensional quantum gravity (perturbed Liouville gravity) is explicitly computed by using the free field approach. The representation considered here is the one recently proposed in [G. Giribet, Nucl. Phys. B 737 (2006) 209] to describe the string theory in AdS3 space. Consequently, this computation extends previous results which presented free field calculations of particular cases of string amplitudes, and confirms that the free field approach leads to the exact result. Remarkably, this representation allows to compute winding violating three-point functions without making use of the spectral flow operator.Facultad de Ciencias Exacta

Correspondence in anticipation of The question concernig technology

A continuación, presentamos la traducción comentada de un intercambio epistolar entre Werner Heisenberg y Martin Heidegger: una carta fechada en octubre de 1953 que cobra importancia en tanto se relaciona estrechamente con la conferencia que Heisenberg dictaría pocos meses después y que luego aparecería referida por Heidegger en La pregunta por la técnica [Die Frage nach der Technik] (1954). Esta carta, aunque brevísima, es densa en referencias a cuestiones que aparecerían poco después en La pregunta por la técnica; cuestiones tales como el peligro que está en germen en que los aspectos científicos del mundo sean considerados como los únicos, esa “unilateralidad peligrosa” [gefährlichen Einseitigkeit]. De las poquísimas referencias en La pregunta por la técnica, las dos menciones a Heisenberg en el texto quedan en relieve. Es, por esto, interesante mostrar que antes de la publicación de La pregunta por la técnica Heidegger había debatido sobre estas cuestiones con lo más granado de la comunidad científica de su espacio y su tiempo.Herein, we present a commented translation of an epistolary exchange between Werner Heisenberg and Martin Heidegger: a letter dated October 1953, which results important in that it is closely related to the lecture that Heisenberg would deliver a few months later and which would later appear to be referred to by Heidegger in The Question Concerning Technology (Die Frage nach der Technik) (1954). This letter, although very brief, is dense in references to issues that would appear soon after in The Question Concerning Technology; questions such as the danger of the scientific aspects of the world being considered as the only ones, that "dangerous one-sidedness" (gefährlichen Einseitigkeit). Of the very few references in The Question Concerning Technology, the two references to Heisenberg are highlighted that text. It is, therefore, interesting to show that before the publication of The Question Concerning Technology, Heidegger had debated these questions with the best of the scientific community of his space and time

On Spectral Flow Symmetry and Knizhnik-Zamolodchikov Equation

It is well known that five-point function in Liouville field theory provides a representation of solutions of the SL(2,R)_k Knizhnik-Zamolodchikov equation at the level of four-point function. Here, we make use of such representation to study some aspects of the spectral flow symmetry of sl(2)_k affine algebra and its action on the observables of the WZNW theory. To illustrate the usefulness of this method we rederive the three-point function that violates the winding number in SL(2,R) in a very succinct way. In addition, we prove several identities holding between exact solutions of the Knizhnik-Zamolodchikov equation.Comment: 10 pages, no figures. v2: Typos corrected, formula and references added. v3: typo corrected in equation (20

On spectral flow symmetry and Knizhnik-Zamolodchikov equation

It is well known that five-point function in Liouville field theory provides a representation of solutions of the SL (2, R) k Knizhnik–Zamolodchikov equation at the level of four-point function. Here, we make use of such representation to study some aspects of the spectral flow symmetry of sl ˆ (2) k affine algebra and its action on the observables of the WZNW theory. To illustrate the usefulness of this method we rederive the three-point function that violates the winding number in SL (2, R) in a very succinct way. In addition, we prove several identities holding between exact solutions of the Knizhnik–Zamolodchikov equation.Instituto de Física La Plat

Three-point function in perturbed Liouville gravity

Three-point correlation function in perturbed conformal field theory coupled to two-dimensional quantum gravity (perturbed Liouville gravity) is explicitly computed by using the free field approach. The representation considered here is the one recently proposed in [G. Giribet, Nucl. Phys. B 737 (2006) 209] to describe the string theory in AdS3 space. Consequently, this computation extends previous results which presented free field calculations of particular cases of string amplitudes, and confirms that the free field approach leads to the exact result. Remarkably, this representation allows to compute winding violating three-point functions without making use of the spectral flow operator.Facultad de Ciencias Exacta

Hoffmann-Infeld black hole solutions in Lovelock gravity

Five-dimensional black holes are studied in Lovelock gravity coupled to Hoffmann–Infeld nonlinear electrodynamics. It is shown that some of these solutions present a double peak behaviour of the temperature as a function of the horizon radius. This feature suggests that the evaporation process, though drastic for a period, leads to an eternal black-hole remnant. In fact, the form of the caloric curve corresponds to the existence of a plateau in the evaporation rate, which implies that black holes of intermediate scales turn out to be unstable. The geometrical aspects, such as the absence of conical singularity, the structure of horizons, etc are also discussed. In particular, solutions that are asymptotically AdS arise for special choices of the parameters, corresponding to charged solutions of five-dimensional Chern–Simons gravity.Facultad de Ciencias ExactasConsejo Nacional de Investigaciones Científicas y Técnica