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Search Results: 1 - 10 of 344961 matches for " B. de Carlos "
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Bayesian Analysis of Simple Random Densities  [PDF]
Paulo C. Marques F., Carlos A. de B. Pereira
Open Journal of Statistics (OJS) , 2014, DOI: 10.4236/ojs.2014.45037
Abstract:

A tractable nonparametric prior over densities is introduced which is closed under sampling and exhibits proper posterior asymptotics.

Predictive Analysis of Microarray Data  [PDF]
Paulo C. Marques F., Carlos A. de B. Pereira
Open Journal of Genetics (OJGen) , 2014, DOI: 10.4236/ojgen.2014.41009
Abstract:

Microarray gene expression data are analyzed by means of a Bayesian nonparametric model, with emphasis on prediction of future observables, yielding a method for selection of differentially expressed genes and the corresponding classifier.

Reliability Estimators for the Components of Series and Parallel Systems: The Weibull Model  [PDF]
Felipe L. Bhering, Carlos A. de B. Pereira, Adriano Polpo
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.511157
Abstract:

This paper presents a hierarchical Bayesian approach to the estimation of components’ reliability (survival) using a Weibull model for each of them. The proposed method can be used to estimation with general survival censored data, because the estimation of a component’s reliability in a series (parallel) system is equivalent to the estimation of its survival function with right- (left-) censored data. Besides the Weibull parametric model for reliability data, independent gamma distributions are considered at the first hierarchical level for the Weibull parameters and independent uniform distributions over the real line as priors for the parameters of the gammas. In order to evaluate the model, an example and a simulation study are discussed.

Soft Supersymmetry Breaking from Gaugino Condensation
B. de Carlos,M. Moretti
Physics , 1994, DOI: 10.1016/0370-2693(95)80008-L
Abstract: We study the structure of soft breaking terms in the context of a gaugino condensation scenario. Assuming that the Supergravity Lagrangian is the correct quantum field theory limit, at some momentum scale $\mu_{UV}$, of a more fundamental one, we demonstrate that the correct result is obtained simply by substituting, in the tree level Supergravity Lagrangian, $\lambda \lambda$ (the gaugino condensate) by its vacuum expectation value $\Lambda^3$. In string inspired scenarios this implies, in particular, that the scalar masses are vanishing at the string tree-level and receive a contribution, at the one loop level, which is proportional to the Green Schwarz coefficient $\delta_{GS}$. Our results do not agree with the ones obtained in the effective Lagrangian approach. We study in detail the origin of this discrepancy, and we argue that the use of the supertrace anomaly to determine the effective theory for the condensate does not fix its gravitational interactions, leaving the soft breaking terms and the vacua of the theory unspecified.
Moduli as Inflatons in Heterotic M-theory
T. Barreiro,B. de Carlos
Physics , 1999, DOI: 10.1088/1126-6708/2000/03/020
Abstract: We consider different cosmological aspects of Heterotic M-theory. In particular we look at the dynamical behaviour of the two relevant moduli in the theory, namely the length of the eleventh segment (pi rho) and the volume of the internal six manifold (V) in models where supersymmetry is broken by multiple gaugino condensation. We look at different ways to stabilise these moduli, namely racetrack scenarios with or without non-perturbative corrections to the Kahler potential. The existence of different flat directions in the scalar potential, and the way in which they can be partially lifted, is discussed as well as their possible role in constructing a viable model of inflation. Some other implications such as the status of the moduli problem within these models are also studied.
Cosmological Aspects of Heterotic M-theory
T. Barreiro,B. de Carlos
Physics , 2000,
Abstract: In this talk we discuss a few relevant aspects of heterotic M-theory. These are the stabilization of the two relevant moduli (the length of the eleventh segment (pi rho) and the volume of the internal six manifold (V)) in models where supersymmetry is broken by multiple gaugino condensation and non-perturbative corrections to the Kahler potential; the existence of almost flat directions in the scalar potential; the possibility of lifting them, and their role in constructing a viable model of inflation. Finally, we review the status of the moduli problem within these models. T
Constraining Supergravity Scenarios through the $b\to s,γ$ Decay.
B. de Carlos,J. A. Casas
Physics , 1995, DOI: 10.1016/0370-2693(95)00277-R
Abstract: We evaluate the branching ratio BR($b\rightarrow s,\gamma$) in the minimal supersymmetric standard model (MSSM), determining the corresponding phenomenological restrictions on two attractive supergravity scenarios, namely minimal supergravity and a class of models with a natural solution to the $\mu$ problem. We have included in the calculation some one--loop refinements that have a substantial impact on the results. The numerical results show some disagreements with part of the previous results in the literature, while they are in agreement with others. For minimal supergravity the CLEO upper and lower bounds put important restrictions on the scalar and gaugino masses in both cases $\mu<0$ and $\mu>0$. For the other supergravity scenarios the relevant CLEO bound is the upper one. It is stressed the fact that an eventual improvement of the experimental bounds of order $10^{-4}$ would strengthen the restrictions on the MSSM dramatically. This would be enough to discard these supergravity scenarios with $\mu<0$ if no discrepancy is found with the standard model prediction, while for $\mu>0$ there will remain low-energy windows.
Supergravity and the $b\to s,γ$ decay
B. de Carlos,J. A. Casas
Physics , 1995,
Abstract: We evaluate the branching ratio BR($b\rightarrow s,\gamma$) in the minimal supersymmetric standard model (MSSM), determining the corresponding phenomenological restrictions on two attractive supergravity scenarios, namely minimal supergravity and a class of models with a natural solution to the $\mu$ problem. We have included in the calculation some one--loop refinements that have a substantial impact on the results. It is stressed the fact that an eventual improvement of the experimental bounds of order $10^{-4}$ would strengthen the restrictions on the MSSM dramatically. This would be enough to discard these supergravity scenarios with $\mu<0$ if no discrepancy is found with the standard model prediction, while for $\mu>0$ there will remain low-energy windows.
Relic Abundances and Detection Rates of Neutralinos in String-Inpired Supergravity Models
B. de Carlos,G. V. Kraniotis
Physics , 1996,
Abstract: We calculate ``relic abundances'' and ``detection rates'' of the neutralino (LSP) in string-inspired supergravity models with ``dilaton-moduli'' induced supersymmetry breaking. In particular we investigate ``universal'' scenarios for the soft-supersymmetry breaking terms from Calabi-Yau compactifications, as well as from the dilaton-dominated limit. ``Non-universal'' scenarios from orbifold string theory are also incorporated into the analysis. In all cases, in the cosmologically interesting region, we find $m_{LSP}\geq 50$ GeV and direct-detection rates in the range O($10^{-3}$ events/(Kg day)) - O($10^{-4}$ events/(Kg day)). ``Indirect-detection'' rates from LSPs captured in the Sun are also calculated.
R-Parity Violation and Quark Flavour Violation
B. de Carlos,P. L. White
Physics , 1996, DOI: 10.1103/PhysRevD.55.4222
Abstract: We investigate the implications of $R$-Parity violation (RPV) for quark flavour violation both by constraining the sneutrino masses to be positive and by studying the processes $b\to s\gamma$ and $K^0-\bar K^0$ mixing. In the latter there are two major contributions, one from ``direct'' one loop diagrams involving RPV couplings, and one from the ``indirect'' contributions generated by the renormalisation group. We compare the effects and discuss the implications of our results.
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