Regular 3-charge 4D black holes and their microscopic description

The perturbative $\alpha^{\prime}$ corrections to Type-IIA String Theory compactified on a Calabi-Yau three-fold allow the construction of regular three-charge supersymmetric black holes in four dimensions, whose entropy scales with the charges as $S \sim \left( p^1 p^2 p^3\right)^{\frac{2}{3}}$. We construct an M-theory uplift of these quantum black holes and show that they can be interpreted as arising from three stacks of M2 branes on a conical singularity. This in turns allow us relate them via a series of dualities to a system of D3 branes carrying momentum and thus to give a microscopic interpretation of their entropy.Comment: 20 pages, LaTe

Interface properties of the NiMnSb/InP and NiMnSb/GaAs contacts

We study the electronic and magnetic properties of the interfaces between the half-metallic Heusler alloy NiMnSb and the binary semiconductors InP and GaAs using two different state-of-the-art full-potential \textit{ab-initio} electronic structure methods. Although in the case of most NiMnSb/InP(001) contacts the half-metallicity is lost, it is possible to keep a high degree of spin-polarization when the interface is made up by Ni and P layers. In the case of the GaAs semiconductor the larger hybridization between the Ni-$d$ and As-$p$ orbitals with respect to the hybridization between the Ni-$d$ and P-$p$ orbitals destroys this polarization. The (111) interfaces present strong interface states but also in this case there are few interfaces presenting a high spin-polarization at the Fermi level which can reach values up to 74%.Comment: 9 pages, 9 figure

Leptin and Its Emerging Role in Children and Adolescents

Leptin is an adipocyte-secreted hormone which plays a key role in energy homeostasis. Recent “proof of concept” studies involving leptin administration to humans support its critical role in regulating energy homeostasis, neuroendocrine and immune function as well as insulin resistance in states of energy/ caloric deprivation. Moreover, interventional studies in leptin deficient children and observational studies in normal girls and boys support a role for leptin as a permissive factor for the initiation of puberty in children. The potential clinical usefulness of leptin in several disease states in children and adolescents, including hypothalamic amenorrhea, eating disorders and syndromes of insulin resistance is still under investigation

Exotic polarizations of D2 branes and oblique vacua of (S)YM2+1_{2+1}

We investigate the oblique vacua in the perturbed 2+1 dimensional gauge theory living on D2 branes. The string theory dual of these vacua is expected to correspond to polarizations of the D2 branes into NS5 branes with D4 brane charge. We perturb the gauge theory by adding fermions masses. In the nonsupersymmetric case, we also consider the effect of slight variations of the masses of the scalars. For certain ranges of scalar masses we find oblique vacua. We show that D4 charge is an essential ingredient in understanding D2 -> NS5 polarizations. We find that some of the polarization states which appear as metastable vacua when D4 charge is not considered are in fact unstable. They decay by acquiring D4 charge, tilting and shrinking to zero size.Comment: 15 pages, 3 figures, LaTe

Propagators for p-forms in AdS_{2p+1} and correlation functions in the AdS_7/(2,0) CFT correspondence

In AdS_{2p+1} we construct propagators for p-forms whose lagrangians contain terms of the form A / d A. In particular we explore the case of forms satisfying ``self duality in odd dimensions'', and the case of forms with a topological mass term. We point out that the ``complete'' set of maximally symmetric bitensors previously used in all the other propagator papers is incomplete - there exists another bitensor which can and does appear in the formulas for the propagators in this particular case. Nevertheless, its presence does not affect the other propagators computed so far. On the AdS side of the correspondence we compute the 2 and 3 point functions involving the self-dual tensor of the maximal 7d gauged supergravity (sugra), S_{\mu\nu\rho}. Since the 7 dimensional antisymmetric self-dual tensor obeys first order field equations (S + * d S=0), to get a nonvanishing 2 point function we add a certain boundary term (to satisfy the variational principle on a manifold with boundary) to the 7d action. The 3 point functions we compute are of the type SSB and SBB, describing vertex interactions with the gauge fields B_{\mu}.Comment: 21 pages, Latex file, one reference adde

Isospectral domains with mixed boundary conditions

We construct a series of examples of planar isospectral domains with mixed Dirichlet-Neumann boundary conditions. This is a modification of a classical problem proposed by M. Kac.Comment: 9 figures. Statement of Theorem 5.1 correcte

A Note on (Meta)stable Brane Configurations in MQCD

We examine the M-theory version of SQCD which is known as MQCD. In the IIA limit, this theory appears to have a supersymmetry-breaking brane configuration which corresponds to the meta-stable state of N=1 SU(Nc) SQCD. However, the behavior at infinity of this non-supersymmetric brane construction differs from that of the supersymmetric ground state of MQCD. We interpret this to mean that it is not a meta-stable state in MQCD, but rather a state in another theory. This provides a concrete example of the fact that, while MQCD accurately describes the supersymmetric features of SCQD, it fails to reproduce its non-supersymmetric features (such as meta-stable states) not only quantitatively but also qualitatively.Comment: 30 pages, 7 figures, harvmac. v2 typo correcte

Variability Abstraction and Refinement for Game-Based Lifted Model Checking of Full CTL

One of the most promising approaches to fighting the configuration space explosion problem in lifted model checking are variability abstractions. In this work, we define a novel game-based approach for variability-specific abstraction and refinement for lifted model checking of the full CTL, interpreted over 3-valued semantics. We propose a direct algorithm for solving a 3-valued (abstract) lifted model checking game. In case the result of model checking an abstract variability model is indefinite, we suggest a new notion of refinement, which eliminates indefinite results. This provides an iterative incremental variability-specific abstraction and refinement framework, where refinement is applied only where indefinite results exist and definite results from previous iterations are reused. The practicality of this approach is demonstrated on several variability models

Extreme plasma states in laser-governed vacuum breakdown

Triggering vacuum breakdown at the upcoming laser facilities can provide rapid electron-positron pair production for studies in laboratory astrophysics and fundamental physics. However, the density of the emerging plasma should seemingly stop rising at the relativistic critical density, when the plasma becomes opaque. Here we identify the opportunity of breaking this limit using optimal beam configuration of petawatt-class lasers. Tightly focused laser fields allow plasma generation in a small focal volume much less than ${\lambda}^3$, and creating extreme plasma states in terms of density and produced currents. These states can be regarded as a new object of nonlinear plasma physics. Using 3D QED-PIC simulations we demonstrate the possibility of reaching densities of more than $10^{25}$ cm$^{-3}$, which is an order of magnitude higher than previously expected. Controlling the process via the initial target parameters gives the opportunity to reach the discovered plasma states at the upcoming laser facilities

Mergers and Typical Black Hole Microstates

We use mergers of microstates to obtain the first smooth horizonless microstate solutions corresponding to a BPS three-charge black hole with a classically large horizon area. These microstates have very long throats, that become infinite in the classical limit; nevertheless, their curvature is everywhere small. Having a classically-infinite throat makes these microstates very similar to the typical microstates of this black hole. A rough CFT analysis confirms this intuition, and indicates a possible class of dual CFT microstates. We also analyze the properties and the merging of microstates corresponding to zero-entropy BPS black holes and black rings. We find that these solutions have the same size as the horizon size of their classical counterparts, and we examine the changes of internal structure of these microstates during mergers.Comment: 49 pages, 5 figures. v2 references adde