The Wasteland of Random Supergravities

We show that in a general \cal{N} = 1 supergravity with N \gg 1 scalar fields, an exponentially small fraction of the de Sitter critical points are metastable vacua. Taking the superpotential and Kahler potential to be random functions, we construct a random matrix model for the Hessian matrix, which is well-approximated by the sum of a Wigner matrix and two Wishart matrices. We compute the eigenvalue spectrum analytically from the free convolution of the constituent spectra and find that in typical configurations, a significant fraction of the eigenvalues are negative. Building on the Tracy-Widom law governing fluctuations of extreme eigenvalues, we determine the probability P of a large fluctuation in which all the eigenvalues become positive. Strong eigenvalue repulsion makes this extremely unlikely: we find P \propto exp(-c N^p), with c, p being constants. For generic critical points we find p \approx 1.5, while for approximately-supersymmetric critical points, p \approx 1.3. Our results have significant implications for the counting of de Sitter vacua in string theory, but the number of vacua remains vast.Comment: 39 pages, 9 figures; v2: fixed typos, added refs and clarification

Fluctuations at the edges of the spectrum of the full rank deformed GUE

5 figures, 44 pagesInternational audienceWe consider a full rank deformation of the GUE $W_N+A_N$ where $A_N$ is a full rank Hermitian matrix of size $N$ and $W_N$ is a GUE. The empirical eigenvalue distribution $\mu_{A_N}$ of $A_N$ converges to a probability distribution $\nu$. We identify all the possible limiting eigenvalue statistics at the edges of the spectrum, including outliers, edges and merging points of connected components of the limiting spectrum. The results are stated in terms of a deterministic equivalent of the empirical eigenvalue distribution of $W_N+A_N$, namely the free convolution of the semi-circle distribution and the empirical eigenvalues distribution of $A_N$

Efeito dos níveis energéticos em dietas isoprotéicas sobre o desempenho, taxa metabólica e hormônios tireoideanos em frangos

Submitted by Franciele Moreira ([email protected]) on 2018-03-13T16:32:47Z No. of bitstreams: 2 Artigo - Otto Mack Junqueira - 1999.pdf: 158899 bytes, checksum: 78afd5849aa656a3ae6c8f2e25c7ec26 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Luciana Ferreira ([email protected]) on 2018-03-14T11:15:48Z (GMT) No. of bitstreams: 2 Artigo - Otto Mack Junqueira - 1999.pdf: 158899 bytes, checksum: 78afd5849aa656a3ae6c8f2e25c7ec26 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Made available in DSpace on 2018-03-14T11:15:48Z (GMT). No. of bitstreams: 2 Artigo - Otto Mack Junqueira - 1999.pdf: 158899 bytes, checksum: 78afd5849aa656a3ae6c8f2e25c7ec26 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 1999Foram testados três níveis de energia (2 600, 2 900 e 3 200 kcal EM/kg) para estudar a influência dos mesmos em dietas isoprotéicas, sobre o desempenho, níveis plasmáticos dos hormônios tireoideanos e a taxa metabólica aos 28 e 49 dias de idade nas temperaturas de 15ºC, 25ºC e 35ºC em frangos de corte. Aves que receberam dietas com maior nível energético apresentaram melhor ganho de peso e maior consumo de ração. A taxa metabólica foi dependente da idade das aves e da temperatura ambiente, não sendo influenciada pelo nível energético da dieta. Não foi observado correlação entre a concentração plasmática dos hormônios tireoideanos e a energia ingerida.A study was conducted on the effects of three dietary energy levels (2 600, 2 900, and 3 200 Kcal EM/kg) in isoproteinic diets for broiler chicks, on the productive performance, plasma thyroid hormone (T4 and T3) levels and metabolic rate, determined at 28 and 49 days of age and at environmental temperatures of 15ºC, 25ºC, and 35ºC. Birds fed the highest energy level showed the most rapid weight gain and greater feed intake. Metabolic rate was dependent on ambient temperature and age of the birds, but not on the dietary energy level. No correlation was observed between plasma thyroid hormone concentration and energy intake