Hairy black holes in N=2 gauged supergravity

We construct black holes with scalar hair in a wide class of four-dimensional N=2 Fayet-Iliopoulos gauged supergravity theories that are characterized by a prepotential containing one free parameter. Considering the truncated model in which only a single real scalar survives, the theory is reduced to an Einstein-scalar system with a potential, which admits at most two AdS critical points and is expressed in terms of a real superpotential. Our solution is static, admits maximally symmetric horizons, asymptotically tends to AdS space corresponding to an extremum of the superpotential, but is disconnected from the Schwarzschild-AdS family. The condition under which the spacetime admits an event horizon is addressed for each horizon topology. It turns out that for hyperbolic horizons the black holes can be extremal. In this case, the near-horizon geometry is AdS_2 x H^2, where the scalar goes to the other, non-supersymmetric, critical point of the potential. Our solution displays fall-off behaviours different from the standard one, due to the fact that the mass parameter $m^2=-2/\ell^2$ at the supersymmetric vacuum lies in a characteristic range $m^2_{BF}\le m^2\le m^2_{\rm BF}+\ell^{-2}$ for which the slowly decaying scalar field is also normalizable. Nevertheless, we identify a well-defined mass for our spacetime, following the prescription of Hertog and Maeda. Quite remarkably, the product of all horizon areas is not given in terms of the asymptotic cosmological constant alone, as one would expect in absence of electromagnetic charges and angular momentum. Our solution shows qualitatively the same thermodynamic behaviour as the Schwarzschild-AdS black hole, but the entropy is always smaller for a given mass and AdS curvature radius. We also find that our spherical black holes are unstable against radial perturbations.Comment: 25 pages, 3 figures, uses jheppub.sty. v2: Refs. and some comments adde

BPS domain walls in N=4 supergravity and dual flows

We establish the conditions for supersymmetric domain wall solutions to N=4 gauged supergravity in five dimensions. These read as BPS first-order equations for the warp factor and the scalar fields, driven by a superpotential and supplemented by a set of constraints that we specify in detail. Then we apply our results to certain consistent truncations of IIB supergravity, thus exploring their dual field theory renormalization group flows. We find a universal flow deforming superconformal theories on D3-branes at Calabi-Yau cones. Moreover, we obtain a superpotential for the solution corresponding to the baryonic branch of the Klebanov-Strassler theory, as well as the superpotential for the flow describing D3 and wrapped D5-branes on the resolved conifold.Comment: 42 pages, 1 figure. v2: minor changes, matches published versio

Supersymmetric Lifshitz-like backgrounds from N=4 SYM with heavy quark density

We examine a class of gravity backgrounds obtained by considering the backreaction of a spatially uniform density of mutually BPS Wilson lines or heavy quarks in N=4 SUSY Yang-Mills theory. The configurations preserve eight supercharges and an SO(5) subgroup of the SO(6) R-symmetry. They are obtained by considering the 1/4-BPS geometries associated to smeared string/D3-brane (F1-D3) intersections. We argue that for the (partially) localized intersection, the geometry exhibits a flow from AdS_5 x S^5 in the UV to a novel IR scaling solution displaying anisotropic Lifshitz-like scaling with dynamical critical exponent z=7, hyperscaling violation and a logarithmic running dilaton. We also obtain a two-parameter family of smeared 1/4-BPS solutions on the Coulomb branch of N=4 SYM exhibiting Lifshitz scaling and hyperscaling violation. For a certain parametric range these yield IR geometries which are conformal to AdS_2 x R^3, and which have been argued to be relevant for fermionic physics.Comment: 24 pages, 2 figures, references added, version published in JHEP, Feb. 201

Identification and characterization of genes preferentially expressed in embryonic telencephalon and CNS stem cells

One of the major goals in developmental neurobiology is to unravel the molecular programs controlling telencephalic development and neural differentiation. The complexity of brain cell types and circuits is reflected in the complexity of gene expression patterns in the brain. It is believed that perhaps a third to half of all genes are largely or exclusively dedicated to directing development, maintenance and functioning of the brain. In mammals, formation of the complex brain structure occurs over the long period of prenatal development. During this period neural progenitor cells must be instructed to undergo proper proliferation, migration, differentiation and connectivity. The aim of my study was to identify genes, within a collection of novel genes preferentially expressed in the embryonic telencephalon, controlling such processed in the mammalian forebrain. To this aim, as a preliminary step, an EST sequencing approach has been undertaken to catalogue and array the repertoire of genes represented in a subtractive library optimized to select rate or unique cDNAs preferentially expressed in the E14.5 mouse telencephalon (named "Telencephalic Embryonic Subtracted Sequences" (Porteus et al., 1992)). The hypothesis driving the production of such a library was that genes preferentially expressed during embryogenesis are likely to be specifically involved in the development of the telencephalon and in the biology of the neural progenitor cells. The selected transcriptome of 1026 unique cDNAs has been used to generate a unique microarray, and to perform gene expression profiling experiments on: (i) mice mutant for transcription factors involved in forebrain development (D1x1/2, Nkx2.1, Pax6, Ngn1/2), (ii) in vitro cultured neural stem cells, committed neural progenitor cells (transient amplifying) and terminally differentiated neural cells. The analysis of the resulting expression profiles has allowed the identification of novel genes that are candidates for playing a major role in neurogenesis and telencephalic development. The differential expression identified with the Tess has been validated using RNA in situ hybridization on embryonic tissue. Two novel genes (corresponding to Tess 28.8E and Tess 31.5E) have been found to be specifically down regulated in D1x1/2-/- subpallium (-46,51 fold for 28.8E; -6,44 fold for 31.5E), and up regulated in Pax6-/- (4,34 for 28.8E; 3,15 for 31.5E) and Ngn1/2-/- (9,02 for 28.8e; 5,04 for 31.5E) pallium The microarray experiments on neural stem cells allowed the identification of a selection of genes putatively involved in the process of self-renewal, lineage commitment and differentiation. Some of these genes have been analysed by RNA in situ hybridizations and demonstrated interesting restricted expression patterns in the developing telencephalon

Three-dimensional super Yang-Mills with unquenched flavor

We construct analytically the gravity duals of three-dimensional, super Yang-Mills-type theories with $\mathcal N=1$ supersymmetry coupled to $N_f$ quark flavors. The backreaction of the quarks on the color degrees of freedom is included, and corresponds on the gravity side to the backreaction of $N_f$ D6-branes on the background of $N$ D2-branes. The D6-branes are smeared over the compact part of the geometry, which must be a six-dimensional nearly K\"ahler manifold in order to preserve supersymmetry. For massless quarks, the solutions flow in the IR to an $AdS_4$ fixed point dual to a Chern-Simons-matter theory. For light quarks the theories exhibit quasi-conformal dynamics (walking) at energy scales $m_q \ll E \ll \lambda N_f / N$, with $\lambda = g_{\text{YM}}^2 N$ the 't Hooft coupling.Comment: 21 pages, 1 figure. v2 Minor editing, refs. added. Tallies with published versio

Renormalized masses of heavy Kaluza-Klein states

Several ways of computing the radiative corrections to the heavy boson masses in Kaluza-Klein theory are discussed. It is argued that only an intrinsically higher dimensional approach embodies all the desired physical properties.Comment: LaTeX, 22 pages. Fully rewritten and streamlined. Five and six dimensional cases treated separatelly. References adde

Estudo cinético da reação da hidroxilamina e n-metilhidroxilamina com o anidrido 1,8-naftálico

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Físicas e Matemáticas. Curso de Química.Reações de transacilação têm sido objeto de intensa pesquisa devido a sua grande importância em sistemas bioquímicos. Estas aparecem nas reações de derivados funcionais de ácidos carboxílicos e no mecanismo de ação de enzimas hidrolíticas em sistemas biológicos. O entendimento da reatividade dos grupos nucleófugos e nucleófilos participantes da reação torna-se altamente importante. Um exemplo é a pesquisa de nucleófilos estáveis na detoxificação química, chamados nucleófilos detentores do efeito alfa1. Anidridos reagem eficientemente com aminas primárias e secundárias, fornecendo amidas, via reação de transacilação, estas por sua vez fornecem imidas pela perda de uma molécula de água. A reação de transacilação do anidrido 1,8- naftálico com a hidroxilamina e a N-metilhidroxilamina, ambos nucleófilos detentores do efeito alfa, fornece a N-hidroxiftalimida e o ácido naftalâmico, respectivamente. As constantes de velocidade de segunda ordem obtidas, quando comparados a valores para reações do anidrido 1,8-naftálico com outras aminas primárias, mostram que a reação do anidrido com a hidroxilamina e seu derivado é pelo menos 100 vezes mais rápida, um indicativo da maior nucleofilicidade da hidroxilamina devido o efeito α. Um gráfico de kobs versus a concentração da amina é linear indicando que a reação é de primeira ordem em relação as aminas estudadas o que exclui a participação de uma segunda molécula da amina catalisando a reação de transacilação e atuação da mesma num processo de catálise ácido-base geral. Os resultados até o momento não permitem inferências sobre a etapa limitante da velocidade, mas ainda assim um mecanismo genérico, que satisfaz o conjunto de dados experimentais até agora obtido, pode ser postulado