Superconformal Interpretation of BPS States in AdS Geometries

We carry out a general analysis of the representations of the superconformal algebras SU(2, 2/N), OSp(8/4, ), and OSp(8*/2N) and give their realization in superspace. We present a construction of their UIRs by multiplication of the different types of massless superfields (supersingletons). Particular attention is paid to the so-called short multiplets. Representations undergoing shortening have protected dimension and may correspond to BPS states in the dual supergravity theory in anti-de Sitter space. These results are relevant for the classification of multitrace operators in boundary conformally invariant theories as well as for the classification of AdS black holes preserving different fractions of supersymmetry.     

Evidence of electron fractionalization from photoemission spectra in the high temperature superconductors

In the normal state of the high temperature superconductors Bi(2)Sr(2)CaCu(2)O(8+delta) and La2(-x)Sr(x)CuO4, and in the related "stripe ordered" material, La(1.25)Nd(0.6)Sr(0.15)CuO4, there is sharp structure in the measured single hole spectral function, A<(k-->,omega), considered as a function of k--> at fixed small binding energy omega. At the same time, as a function of omega at fixed k--> on much of the putative Fermi surface, any structure in A<(k-->,omega), other than the Fermi cutoff, is very broad. This is characteristic of the situation in which there are no stable excitations with the quantum numbers of the electron, as is the case in the one-dimensional electron gas.     

Silver baits for the "miraculous draught" of amphiphilic lanthanide helicates

The axial connection of flexible thioalkyls chains of variable length (n=1–12) within the segmental bis‐tridentate 2‐benzimidazole‐8‐hydroxyquinoline ligands [ L12 ^Cn?2 H]^2? provides amphiphilic receptors designed for the synthesis of neutral dinuclear lanthanides helicates. However, the stoichiometric mixing of metals and ligands in basic media only yields intricate mixtures of poorly soluble aggregates. The addition of Ag^I in solution restores classical helicate architectures for n=3, with the quantitative formation of the discrete D₃‐symmetrical [Ln₂Ag2( L12 ^C3?2 H)₃]²⁺ complexes at millimolar concentration (Ln=La, Eu, Lu). The X‐ray crystal structure supports the formation of [La₂Ag₂( L12 ^C3?2 H)₃][OTf]₂, which exists in the solid state as infinite linear polymers bridged by S‐Ag‐S bonds. In contrast, molecular dynamics (MD) simulations in the gas phase and in solution confirm the experimental diffusion measurements, which imply the formation of discrete molecular entities in these media, in which the sulfur atoms of each lipophilic ligand are rapidly exchanged within the Ag^I coordination sphere. Turned as a predictive tool, MD suggests that this Ag^I templating effect is efficient only for n=1–3, while for n>3 very loose interactions occur between Ag^I and the thioalkyl residues. The subsequent experimental demonstration that only 25 % of the total ligand speciation contributes to the formation of [Ln₂Ag₂( L12 ^C12?2 H)₃]²⁺ in solution puts the bases for a rational approach for the design of amphiphilic helical complexes with predetermined molecular interfaces.