Higher Spin Entanglement and W_N Conformal Blocks

Two-dimensional conformal field theories with extended $\cal{W}$-symmetry algebras have dual descriptions in terms of weakly coupled higher spin gravity in AdS$_3\,$ at large central charge. Observables that can be computed and compared in the two descriptions include R\'enyi and entanglement entropies, and correlation functions of local operators. We develop techniques for computing these, in a manner that sheds light on when and why one can expect agreement between such quantities on each side of the duality. We set up the computation of excited state R\'enyi entropies in the bulk in terms of Chern-Simons connections, and show how this directly parallels the CFT computation of correlation functions. More generally, we consider the vacuum conformal block for general operators with $\Delta \sim c\,$. When two of the operators obey ${\Delta \over c} \ll 1\,$, we show by explicit computation that the vacuum conformal block is computed by a bulk Wilson line probing an asymptotically AdS$_3$ background with higher spin fields excited, the latter emerging as the effective bulk description of the excited state produced by the heavy operators. Among other things, this puts a previous proposal for computing higher spin entanglement entropy via Wilson lines on firmer footing, and clarifies its relation to CFT. We also study the corresponding computation in Toda theory and find that this provides yet another independent way to arrive at the same result.Comment: 56 page

Road Safety Valuation under a Stated Choice Framework

The value of fatal risk reductions is a vital input for road safety cost-benefit analysis. It has been traditionally estimated by means of contingent valuation in spite of growing criticism surrounding this approach. Furthermore, many believe that risk-money trade-offs are not well understood due to the difficulty in internalizing tiny risks. We have succeeded in applying the Stated Choice (SC) approach to tackle this problem, using as one of the attributes the number of accidents with fatal victims (i.e. a proxy for risk). To assess the robustness of SC, we conducted an external validity test based on results for three different studies. We investigated if preferences were well defined according to economic theory (i.e. as initial risk increases, the marginal willingness-to-pay should be higher). We also addressed the generally ignored issue of whether there should be a unique value of fatal risk reductions. We found that people can internalize risk consistently from an economic viewpoint, and that although each sample yields different values of risk reductions, there was a relationship between the risk level and the value of risk reductions in each context examined; this evidence could be most helpful within the context of developing countries. Finally, we offer an hypothesis to explain the differences between our values with those obtained in industrialised countries, highlighting the importance of doing local studies rather than transferring imported values

Directional shift current in mirror-symmetric BC2_2N

We present a theoretical study of the shift current in a noncentrosymmetric polytype of graphitic BC$_2$N. We find that the photoconductivity near the fundamental gap is strongly anisotropic due to the vanishing of particular tensor components not foretold by point-group symmetry arguments; this is a consequence of dipole selection rules imposed by mirror symmetry, which imply that the relative parities between valence and conduction bands are key for determining the directionality of the band-edge response. In addition, the band-edge photoconductivity turns out to be rather large, with the peak value occurring in an energy range suitable for optical manipulationComment: 7 pages, 4 figure

Cortes de Bribiesca : celebradas en el año de 1387

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

Cortes de Palencia : celebradas en el año de 1388

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

Evolucion y perspectivas del sector vitivinicola

Peer Reviewe