A new AdS_4/CFT_3 Dual with Extended SUSY and a Spectral Flow

We construct a new AdS_4 background in Type IIB supergravity by means of a non-Abelian T-duality transformation on the Type IIA dual of ABJM. The analysis of probe and particle-like branes suggests a dual CFT in which each of the gauge groups is doubled. A common feature of non-Abelian T-duality is that in the absence of any global information coming from String Theory it gives rise to non-compact dual backgrounds, with coordinates living in the Lie algebra of the Lie group involved in the dualization. In backgrounds with CFT duals this poses obvious problems to the CFTs. In this paper we show that for the new AdS_4 background the gauge groups of the associated dual CFT undergo a spectral flow as the non-compact internal direction runs from 0 to infinity, which resembles Seiberg duality in N=1. This phenomenon, very reminiscent of the cascade, provides an interpretation in the CFT for the running of the non-compact coordinate, and suggests that at the end of the flow the extra charges disappear and the dual CFT is described by a 2-node quiver very similar to ABJM, albeit with reduced supersymmetry.Comment: 40 pages, published versio

Minimal flux Minkowski classification

We classify Minkowski$_4$ solutions in type IIA supergravity, with N=2 supersymmetry and an SU(2) R-symmetry of a certain type. Many subcases can be reduced to relatively simple PDEs, among which we recover various intersecting brane systems, and AdS$_d$ solutions, $d=5,6,7$, and in particular the recently found general massive AdS$_7$ solutions. Imposing compactness of the internal six-manifold we obtain promising solutions with localized D-branes and O-planes.Comment: v2: Result slightly strengthened, typos corrected. v3: Published Versio

AdS6AdS_6 T-duals and Type IIB AdS6×S2AdS_6\times S^2 Geometries with 7-Branes

We show that the first $AdS_6$ backgrounds in Type IIB supergravity known in the literature, namely those constructed via T-duality from the Brandhuber-Oz solution to massive IIA, fit within an extension of the global $AdS_6 \times S^2$ solutions with 7-branes warped over a Riemann surface $\Sigma$, recently classified by D'Hoker, Gutperle and Uhlemann, that describes delocalised 5-branes and 7-branes. The solution constructed through Abelian T-duality provides an explicit example of a Riemann surface with the topology of an annulus, that includes D7/O7-branes. In turn, the solution generated through non-Abelian T-duality arises from the upper half-plane.Comment: 36 pages plus appendices. 3 figures. v2: reference added. v3: section 5 improved, version accepted in JHE

A N=2\mathcal{N}=2 Supersymmetric AdS4AdS_4 Solution in M-theory with Purely Magnetic Flux

We find a new $\mathcal{N}=2$ $AdS_4$ solution in M-theory supported by purely magnetic flux via a sequence of abelian and non-abelian T-dualities. This provides the second known example in this class besides the uplift of the Pernici and Sezgin solution to 7d gauged supergravity constructed in the eighties. We compute the free energy of the solution, and show that it scales as $N^{3/2}$. It is intriguing that even though the natural holographic interpretation is in terms of M5-branes wrapped on a special Lagrangian 3-cycle, this solution does not exhibit the expected $N^3$ behavior.Comment: 19 pages plus appendices. v2 metadata amended, reference adde

Wages, racial composition, and quality sorting in labor markets

This paper examines the relationship between wage rates and the racial composition of jobs, using large cross-sectional and longitudinal samples constructed from monthly Current Population Surveys for 1983-92. Support is found for a "quality sorting" model that posits an equilibrium in which the racial composition of jobs serves as a skill index of unmeasured labor quality. Estimation of standard wage-level equations shows that wages of both black and white workers are substantially lower in occupations with a high density of blacks. Consistent with the quality sorting hypothesis, the magnitude of the relationship is reduced sharply after accounting for occupational skill measures. Longitudinal wage-change estimates controlling for person-specific quality indicate little if any causal effect of racial composition on wages. Estimates of racial discrimination are reduced only moderately after accounting for racial composition; unexplained differentials occur within occupations or reflect inter-occupational differences uncorrelated with racial composition and occupational skill measures.

The rent's too high: Self-archive for fair online publication costs

The main contributors of scientific knowledge, researchers, generally aim to disseminate their findings far and wide. And yet, publishing companies have largely kept these findings behind a paywall. With digital publication technology markedly reducing cost, this enduring wall seems disproportionate and unjustified; moreover, it has sparked a topical exchange concerning how to modernize academic publishing. This discussion, however, seems to focus on how to compensate major publishers for providing open access through a "pay to publish" model, in turn transferring financial burdens from libraries to authors and their funders. Large publishing companies, including Elsevier, Springer Nature, Wiley, PLoS, and Frontiers, continue to earn exorbitant revenues each year, hundreds of millions of dollars of which now come from processing charges for open-access articles. A less expensive and equally accessible alternative exists: widespread self-archiving of peer-reviewed articles. All we need is awareness of this alternative and the will to employ itComment: 8 pages, 1 figure, 19 reference