The Application of the Newman-Janis Algorithm in Obtaining Interior Solutions of the Kerr Metric

In this paper we present a class of metrics to be considered as new possible sources for the Kerr metric. These new solutions are generated by applying the Newman-Janis algorithm (NJA) to any static spherically symmetric (SSS) ``seed'' metric. The continuity conditions for joining any two of these new metrics is presented. A specific analysis of the joining of interior solutions to the Kerr exterior is made. The boundary conditions used are those first developed by Dormois and Israel. We find that the NJA can be used to generate new physically allowable interior solutions. These new solutions can be matched smoothly to the Kerr metric. We present a general method for finding such solutions with oblate spheroidal boundary surfaces. Finally a trial solution is found and presented.Comment: 11 pages, Latex, 4 postscript figures. To be published in Classical and Quantum Gravity. Title and abstract are now on the same pag

The Universality of Einstein Equations

It is shown that for a wide class of analytic Lagrangians which depend only on the scalar curvature of a metric and a connection, the application of the so--called ``Palatini formalism'', i.e., treating the metric and the connection as independent variables, leads to ``universal'' equations. If the dimension $n$ of space--time is greater than two these universal equations are Einstein equations for a generic Lagrangian and are suitably replaced by other universal equations at bifurcation points. We show that bifurcations take place in particular for conformally invariant Lagrangians $L=R^{n/2} \sqrt g$ and prove that their solutions are conformally equivalent to solutions of Einstein equations. For 2--dimensional space--time we find instead that the universal equation is always the equation of constant scalar curvature; the connection in this case is a Weyl connection, containing the Levi--Civita connection of the metric and an additional vectorfield ensuing from conformal invariance. As an example, we investigate in detail some polynomial Lagrangians and discuss their bifurcations.Comment: 15 pages, LaTeX, (Extended Version), TO-JLL-P1/9

Universal field equations for metric-affine theories of gravity

We show that almost all metric--affine theories of gravity yield Einstein equations with a non--null cosmological constant $\Lambda$. Under certain circumstances and for any dimension, it is also possible to incorporate a Weyl vector field $W_\mu$ and therefore the presence of an anisotropy. The viability of these field equations is discussed in view of recent astrophysical observations.Comment: 13 pages. This is a copy of the published paper. We are posting it here because of the increasing interest in f(R) theories of gravit

Anomalous diffusion modifies solar neutrino fluxes

Density and temperature conditions in the solar core suggest that the microscopic diffusion of electrons and ions could be nonstandard: Diffusion and friction coefficients are energy dependent, collisions are not two-body processes and retain memory beyond the single scattering event. A direct consequence of nonstandard diffusion is that the equilibrium energy distribution of particles departs from the Maxwellian one (tails goes to zero more slowly or faster than exponentially) modifying the reaction rates. This effect is qualitatively different from temperature and/or composition modification: Small changes in the number of particles in the distribution tails can strongly modify the rates without affecting bulk properties, such as the sound speed or hydrostatic equilibrium, which depend on the mean values from the distribution. This mechanism can considerably increase the range of predictions for the neutrino fluxes allowed by the current experimental values (cross sections and solar properties) and can be used to reduce the discrepancy between these predictions and the solar neutrino experiments.Comment: 16 pages, ReVTeX, no figures. Text partially revised (24 april 1998

Resident and accidental thrips species in potato crops in Prepuna and Puna of Jujuy

Para orientar las estrategias de manejo de plagas es importante precisar la relación funcional fitófago - planta, distinguiendo las especies residentes de las accidentales. En este marco, el concepto de planta hospedadora está restringido a aquella en la cual un insecto cumple su ciclo y mantiene sus poblaciones sucesivamente. Los objetivos fueron a) identificar las especies de tisanópteros que tienen a la papa como planta hospedadora y aquellas que se encuentran accidentalmente, b) reconocer los caracteres morfológicos mas simples de los adultos y larva II y c) analizar aspectos bioecológicos (sitios de alimentación, daño y distribución en Prepuna y Puna). La integración de estos datos servirá de guía para una rápida diferenciación de las especies de trips asociadas al cultivo de papa en la zona. Los ejemplares provienen de colectas realizadas en localidades ubicadas entre los 2050 y 3600msnm. Los muestreos consistieron en hojas y flores de papa, que contenían distintos estados inmaduros. En laboratorio las muestras se acondicionaron en jaulas de cría observándose su desarrollo hasta la emergencia de los adultos, registrándose el sitio de pupación y el tipo de daño. Las especies residentes son: Frankliniella tuberosi Moulton, F. australis Morgan, F. gemina Bagnall, Thrips tabaci Lindemann y las accidentales: F. fulvipes Bagnall, F. schultzei Trybom y F. occidentalis (Pergande). El cultivo de papa es afectado por F. tuberosi en localidades ubicadas en altitudes superiores a los 3000 msnm. F. australis es la mas abundante en la Prepuna, aunque no se registraron daños de consideración.To direct strategies to be adopted in the management of pest control it is important to determine the plant-phytophagous organism functional relation, making a distinction between resident and accidental species. Within this framework, the concept of host plant is restricted to that in which an insect fulfils its life cycle and maintains its populations consecutively. The objetives of this study were: a) To distinguish thrips species that have potato as their host plant from those that are accidentally found, b) To identify the simplest adult and larva II morphological characters, and c) To analyze bioecological aspects (feeding sites, damage, and distribution in Prepuna and Puna). Integration of these data will be a useful guide to determine thrips species associated to potato crops in this área. Samples proceeded from collections made in places located between 2050 and 3600 m.a.s.l. Samplings consisted in pótalo leaves and flowers containing various immalure stages. Samples were placed in breeding cages ¡n the laboralory, moniloring their development unlil adull emergence, recording pupalion siles and type of damage. Resident species found were: Frankliniella tuberos! Moullon, F. australis Morgan, F. gemina Bagnall, Thrips tabaci ÍJndemann, and accidental species, F. fulvipes Bagnall, F. schultzei Trybom and F occidentalis (Pergande). The pótalo crop is affected by F tuberosl in places located above 3000 m.a.s.l. F australis is most abundanl in Prepuna, although no considerable damages were recorded.Fil: Zamar, María Inés. Universidad Nacional de Jujuy. Instituto de Biología de la Altura. Departamento de Entomología; ArgentinaFil: Arce de Hamity, M. G.. Universidad Nacional de Jujuy. Instituto de Biología de la Altura. Departamento de Entomología; ArgentinaFil: Neder, Lilia Estela. Universidad Nacional de Jujuy. Instituto de Biología de la Altura. Departamento de Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Effective supergravity descriptions of superstring cosmology

This text is a review of aspects of supergravity theories that are relevant in superstring cosmology. In particular, it considers the possibilities and restrictions for `uplifting terms', i.e. methods to produce de Sitter vacua. We concentrate on N=1 and N=2 supergravities, and the tools of superconformal methods, which clarify the structure of these theories. Cosmic strings and embeddings of target manifolds of supergravity theories in others are discussed in short at the end.Comment: 12 pages, contribution to the proceedings of the 2nd international conference on Quantum Theories and Renormalization Group in Gravity and Cosmology, Barcelona, July 11-15, 2006, Journal of Physics

Nonextensive Thermostatistics and the H-Theorem

The kinetic foundations of Tsallis' nonextensive thermostatistics are investigated through Boltzmann's transport equation approach. Our analysis follows from a nonextensive generalization of the ``molecular chaos hypothesis". For $q>0$, the $q$-transport equation satisfies an $H$-theorem based on Tsallis entropy. It is also proved that the collisional equilibrium is given by Tsallis' $q$-nonextensive velocity distribution.Comment: 4 pages, no figures, corrected some typo

Power-Law Sensitivity to Initial Conditions within a Logistic-like Family of Maps: Fractality and Nonextensivity

Power-law sensitivity to initial conditions, characterizing the behaviour of dynamical systems at their critical points (where the standard Liapunov exponent vanishes), is studied in connection with the family of nonlinear 1D logistic-like maps $x_{t+1} = 1 - a | x_t |^z, (z > 1; 0 < a \le 2; t=0,1,2,...)$ The main ingredient of our approach is the generalized deviation law \lim_{\Delta x(0) -> 0} \Delta x(t) / \Delta x(0)} = [1+(1-q)\lambda_q t]^{1/(1-q)} (equal to $e^{\lambda_1 t}$ for q=1, and proportional, for large t, to $t^{1/(1-q)}$ for $q \ne 1; q \in R$ is the entropic index appearing in the recently introduced nonextensive generalized statistics). The relation between the parameter q and the fractal dimension d_f of the onset-to-chaos attractor is revealed: q appears to monotonically decrease from 1 (Boltzmann-Gibbs, extensive, limit) to -infinity when d_f varies from 1 (nonfractal, ergodic-like, limit) to zero.Comment: LaTeX, 6 pages , 5 figure

Relative information entropy in cosmology: The problem of information entanglement

The necessary information to distinguish a local inhomogeneous mass density field from its spatial average on a compact domain of the universe can be measured by relative information entropy. The Kullback-Leibler (KL) formula arises very naturally in this context, however, it provides a very complicated way to compute the mutual information between spatially separated but causally connected regions of the universe in a realistic, inhomogeneous model. To circumvent this issue, by considering a parametric extension of the KL measure, we develop a simple model to describe the mutual information which is entangled via the gravitational field equations. We show that the Tsallis relative entropy can be a good approximation in the case of small inhomogeneities, and for measuring the independent relative information inside the domain, we propose the R\'enyi relative entropy formula.Received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under the grant agreement No. PCOFUND-GA-2009-246542; from CMAT through FEDER Funds COMPETE, and also from FCT projects Est-OE/MAT/UI0013/2014, SFRH/BCC/105835/2014 and CERN/FP/123609/2011

Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations