Comments on Proposed Gravitational Modifications of Schrodinger Dynamics and their Experimental Implications

We discuss aspects of gravitational modifications of Schrodinger dynamics proposed by Diosi and Penrose. We consider first the Diosi-Penrose criterion for gravitationally induced state vector reduction, and compute the reduction time expected for a superposition of a uniform density cubical solid in two positions displaced by a small fraction of the cube side. We show that the predicted effect is much smaller than would be observable in the proposed Marshall et al. mirror experiment. We then consider the ``Schrodinger -Newton'' equation for an N-particle system. We show that in the independent particle approximation, it differs from the usual Hartree approximation applied to the Newtonian potential by self-interaction terms, which do not have a consistent Born rule interpretation. This raises doubts about the use of the Schrodinger-Newton equation to calculate gravitational effects on molecular interference experiments. When the effects of Newtonian gravitation on molecular diffraction are calculated using the standard many-body Schrodinger equation, no washing out of the interference pattern is predicted.Comment: Tex, 17

Remarks on a Proposed Super-Kamiokande Test for Quantum Gravity Induced Decoherence Effects

Lisi, Marrone, and Montanino have recently proposed a test for quantum gravity induced decoherence effects in neutrino oscillations observed at Super-Kamiokande. We comment here that their equations have the same qualitative form as the energy conserving objective state vector reduction equations discussed by a number of authors. However, using the Planckian parameter value proposed to explain state vector reduction leads to a neutrino oscillation effect many orders of magnitude smaller than would be detectable at Super-Kamiokande. Similar estimates hold for the Ghirardi, Rimini, and Weber spontaneous localization approach to state vector reduction, and our remarks are relevant as well to proposed $K$ meson and $B$ meson tests of gravity induced decoherence.Comment: 10 pages, plain Tex, no figure

Breaking quantum linearity: constraints from human perception and cosmological implications

Resolving the tension between quantum superpositions and the uniqueness of the classical world is a major open problem. One possibility, which is extensively explored both theoretically and experimentally, is that quantum linearity breaks above a given scale. Theoretically, this possibility is predicted by collapse models. They provide quantitative information on where violations of the superposition principle become manifest. Here we show that the lower bound on the collapse parameter lambda, coming from the analysis of the human visual process, is ~ 7 +/- 2 orders of magnitude stronger than the original bound, in agreement with more recent analysis. This implies that the collapse becomes effective with systems containing ~ 10^4 - 10^5 nucleons, and thus falls within the range of testability with present-day technology. We also compare the spectrum of the collapsing field with those of known cosmological fields, showing that a typical cosmological random field can yield an efficient wave function collapse.Comment: 13 pages, LaTeX, 3 figure

Overview of the Status and Strangeness Capabilities of STAR

STAR is a large acceptance spectrometer capable of precision measurements of a wide variety of strange particles. We discuss the STAR detector, its configuration during the first two years of RHIC operation, and its initial performance for Au+Au collisions. The expected performance for strangeness physics and initial data on strange particle reconstruction in Au+Au collisions are presented.Comment: Proceedings of the Fifth International Conference on Strangeness in Quark Matter, Berkeley, California, July 20-25, 200

Simple Analytic Models of Gravitational Collapse

Most general relativity textbooks devote considerable space to the simplest example of a black hole containing a singularity, the Schwarzschild geometry. However only a few discuss the dynamical process of gravitational collapse, by which black holes and singularities form. We present here two types of analytic models for this process, which we believe are the simplest available; the first involves collapsing spherical shells of light, analyzed mainly in Eddington-Finkelstein coordinates; the second involves collapsing spheres filled with a perfect fluid, analyzed mainly in Painleve-Gullstrand coordinates. Our main goal is pedagogical simplicity and algebraic completeness, but we also present some results that we believe are new, such as the collapse of a light shell in Kruskal-Szekeres coordinates.Comment: Submitted to American Journal of Physic

Origin of the anomalies: the modified Heisenberg equation

The origin of the anomalies is analyzed. It is shown that they are due to the fact that the generators of the symmetry do not leave invariant the domain of definition of the Hamiltonian and then a term, normally forgotten in the Heisenberg equation, gives an extra contribution responsible for the non conservation of the charges. This explanation is equivalent to that of the Fujikawa in the path integral formalism. Finally, this approach is applied to the conformal symmetry breaking in two-dimensional quantum mechanics.Comment: 7 pages, LaTe

Object-guided Spatial Attention in Touch: Holding the Same Object with Both Hands Delays Attentional Selection

Abstract Previous research has shown that attention to a specific location on a uniform visual object spreads throughout the entire object. Here we demonstrate that, similar to the visual system, spatial attention in touch can be object guided. We measured event-related brain potentials to tactile stimuli arising from objects held by observers' hands, when the hands were placed either near each other or far apart, holding two separate objects, or when they were far apart but holding a common object. Observers covertly oriented their attention to the left, to the right, or to both hands, following bilaterally presented tactile cues indicating likely tactile target location(s). Attentional modulations for tactile stimuli at attended compared to unattended locations were present in the time range of early somatosensory components only when the hands were far apart, but not when they were near. This was found to reflect enhanced somatosensory processing at attended locations rather than suppressed processing at unattended locations. Crucially, holding a common object with both hands delayed attentional selection, similar to when the hands were near. This shows that the proprioceptive distance effect on tactile attentional selection arises when distant event locations can be treated as separate and unconnected sources of tactile stimulation, but not when they form part of the same object. These findings suggest that, similar to visual attention, both space- and object-based attentional mechanisms can operate when we select between tactile events on our body surface.</jats:p

Cluster variation - Pade` approximants method for the simple cubic Ising model

The cluster variation - Pade` approximant method is a recently proposed tool, based on the extrapolation of low/high temperature results obtained with the cluster variation method, for the determination of critical parameters in Ising-like models. Here the method is applied to the three-dimensional simple cubic Ising model, and new results, obtained with an 18-site basic cluster, are reported. Other techniques for extracting non-classical critical exponents are also applied and their results compared with those by the cluster variation - Pade` approximant method.Comment: 8 RevTeX pages, 3 PostScript figure

Modèles débit-durée-fréquence d'étiage, concept et usage pour une approche régionale des régimes de basses eaux des bassins hydrographiques de la Loire (France) et du Crisu-Alb (Roumanie)

La modélisation de synthèse en débit-durée-fréquence des régimes d'étiage observés s'inspire de travaux développés ces dernières années sur les modèles continus (multidurée et multifréquence) de prédétermination des crues (GALEA et PRUDHOMME, 1996). La variabilité des régimes d'étiage du bassin hydrographique de la Loire (S=117 000 km2) est étudiée à partir de deux variables hydrologiques, définies sur une durée (d) continue (1≤d≤90j), traduisant deux notions de régime complémentaires : la notion de débit-volume (moyen) minimal (VCNd) annuel et de débit-seuil minimal (QCNd) annuel non dépassé. L'étude statistique multidurée des événements annuels observés en 57 sites sélectionnés, selon la loi log-normale à deux paramètres (écart-type et moyenne), permet de répartir les différents bassins en 4 familles typologiquement homogènes. Pour chacune de ces familles est choisi un bassin versant de référence dont les courbes débit-durée-fréquence normées en débit et durée gagnent alors en représentativité régionale. L'utilisation de ces courbes adimensionnelles est rendue plus aisée, grâce à un formalisme mathématique. La norme de débit retenue est le débit journalier minimal annuel de période moyenne de retour 2 ans. La norme de durée quant à elle est déduite des courbes de tarissement observées et décrites selon l'équation de MAILLET. Ces deux normes (ou encore descripteurs de régime) constituent les seuls paramètres d'entrée des 4 modèles adimensionnels QdF d'étiage. Ces modèles et leur typologie associée, appliqués au bassin hydrographique de la Loire, ont permis de montrer la cohérence des quantiles observés et modélisés en chacun des 57 sites retenus. Une première validation de la méthodologie QdF d'étiage, établie sur le bassin de la Loire, a concerné 12 bassins versants du Crisu-Alb (S=3000 km2) en Roumanie. Cela n'a pas nécessité de nouveaux modèles de référence autres que ceux élaborés pour la Loire. Autrement dit, pour chacun des sites étudiés, la valeur de l'écart-type de la loi ajustée sur les VCNd=1j a permis de choisir la famille hydrologique d'appartenance et donc le modèle QdF d'étiage qui lui est associé. La qualité des modélisations effectuées confirment par ailleurs que les deux descripteurs locaux de régime retenus sont de bons intégrateurs des processus d'écoulement liés aux étiages. D'une manière générale, la démarche a permis d'éprouver la fiabilité de la méthodologie QdF développée en étiage et ces premiers résultats sont encourageants pour l'avenir. Notamment, l'usage opérationnel des modèles QdF d'étiage sur des sites non observés nécessite de poursuivre l'effort de recherche vers une explicitation du critère de choix ainsi que des deux descripteurs locaux du régime de basses eaux.The French Department of the Environment entrusted to the CEMAGREF the realization of a study relating to an ecosystemic approach to the management of the Loire watershed. Over the long term, this approach is designed to establish orientations for the protection and management of the natural aquatic environments of the Loire. To this end, a good knowledge of the variability of the hydrological regimes is necessary. The method presented relates primarily to low flow discharges. In spite of the great heterogeneity in space and time of low flows, a regionalization study of watershed low flow regimes of Loire (S=117 000 km2) has been attempted on the basis of the same QdF (discharge-duration-frequency) concept developed for floods (GALEA and PRUDHOMME, 1996). To allow an objective evaluation of developed methodology, we present here the details of the conceptual approach used to model and synthesize the low flow regimes observed, and present the results obtained.The methodology relates primarily to relatively undisturbed basins with perennial flow. The variability of low flow regimes takes into account two hydrologic variables expressing two notions of complementary regimes: the notion of annual minimal average flow (VCNd), and the annual minimal threshold discharge (QCNd) below which the flow does not decrease for a continuous duration (d) which varies from one day to 90 days. The statistical study of annual events demonstrates that the Log-Normal law (two parameters) is generally adequate for a given duration d. From the low flow typology observed on 57 selected sites, the statistical study of annual events revealed four homogeneous groups of hydrological low flow regimes. In each of the 4 groups a reference basin is chosen. Its flow-duration-frequency curves normalized to discharge and duration show a regional representativity and the mathematical formalism yields easy-to-use dimensionless curves. The normative discharge VCN(2,1) is the minimum annual daily flow for a two year return period. The normative duration of flow (De) of a basin results from the recession curves described by MAILLET's equation. In each group, a large diversity of low flow regimes exists, as indicated by the two local descriptors (De and VCN(2,1)), which are the only input parameters for the low flow QdF models. Concerning the Loire watershed, these 4 models and their associated typology characterize the large diversity in space and time of low flows observed for the 57 studied cases.A first validation of the low flow QdF methodology concerned 12 basins of Crisu-Alb watershed, in Romania. It was not necessary to establish new reference models for the regionalization of low flows for these 12 studied cases in the Crisu-Alb watershed. The quality of the transposed models confirms, on another hand, that the two local descriptors of the low flow regime are good integrators of flow processes in relation with low flows. The initial results from the synthetic low flow models are promising. Use of these models on ungauged basins will require additional research to explain the model's choice criterion and the two local descriptors of the low flow regime