Computational Complexity of Iterated Maps on the Interval (Extended Abstract)

The exact computation of orbits of discrete dynamical systems on the interval is considered. Therefore, a multiple-precision floating point approach based on error analysis is chosen and a general algorithm is presented. The correctness of the algorithm is shown and the computational complexity is analyzed. As a main result, the computational complexity measure considered here is related to the Ljapunow exponent of the dynamical system under consideration

High energy solar neutrinos and p-wave contributions to ^3He(p,\nue^+)^4He

High energy solar neutrinos can come from the hep reaction ^3He(p,\nue^+)^4He with a large end point energy of 18.8 MeV. Understanding the hep reaction may be important for interpreting solar neutrino spectra. We calculate the contribution of the axial charge transition $^3P_0\to ^1S_0$ to the hep thermonuclear S factor using a one-body reaction model involving a nucleon moving in optical potentials. Our result is comparable to or larger than previous calculations of the s-wave Gamow Teller contribution. This indicates that the hep reaction may have p-wave strength leading to an enhancement of the S factor.Comment: 4 pages, 1 ps figure, very minor changes, Phys. Rev. C in pres

COMPARISON OF TRANSVERSE SINGLE BUNCH INSTABILITIES BETWEEN THE ESRF AND ELETTRA

Abstract Transverse single bunch instabilities are measured, analysed and compared between the ESRF and ELETTRA, to obtain a deeper insight, namely how different effects influence coherent transverse motions. Despite the basic similarity of the two machines, being both examples of third generation light sources, it is found that some distinct differences in the relevant parameters such as the energy and optics, as well as the impedance, lead to the appearance of instabilities in a notably different manner. As well as summarising the results of the experiments, modelling of the broadband impedance of the two machines and comparison with expectations are presented

Solar Neutrinos: What We Have Learned

The four operating solar neutrino experiments confirm the hypothesis that the energy source for solar luminosity is hydrogen fusion. However, the measured rate for each of the four solar neutrino experiments differs significantly (by factors of 2.0 to 3.5) from the corresponding theoretical prediction that is based upon the standard solar model and the simplest version of the standard electroweak theory. If standard electroweak theory is correct, the energy spectrum for \b8 neutrinos created in the solar interior must be the same (to one part in $10^5$) as the known laboratory \b8 neutrino energy spectrum. Direct comparison of the chlorine and the Kamiokande experiments, both sensitive to \b8 neutrinos, suggests that the discrepancy between theory and observations depends upon neutrino energy, in conflict with standard expectations. Monte Carlo studies with 1000 implementations of the standard solar model confirm that the chlorine and the Kamiokande experiments cannot be reconciled unless new weak interaction physics changes the shape of the \b8 neutrino energy spectrum. The results of the two gallium solar neutrino experiments strengthen the conclusion that new physics is required and help determine a relatively small allowed region for the MSW neutrino parameters.Comment: LaTeX file, 19 pages. For hardcopy with figures contact [email protected]. Institute for Advanced Study number AST 93/6

Infiltration from surface and buried point sources: The average wetting water content

The assumption in analytical solutions for flow from surface and buried point sources of an average water content, (θ) over bar, behind the wetting front is examined. Some recent work has shown that this assumption fitted some field data well. Here we calculated (θ) over bar using a steady state solution based on the work by Raats [1971] and an exponential dependence of the diffusivity upon the water content. This is compared with a constant value of (θ) over bar calculated from an assumption of a hydraulic conductivity at the wetting front of 1 mm day(-1) and the water content at saturation. This comparison was made for a wide range of soils. The constant (θ) over bar generally underestimated (θ) over bar at small wetted radii and overestimated (θ) over bar at large radii. The crossover point between under and overestimation changed with both soil properties and flow rate. The largest variance occurred for coarser texture soils at low-flow rates. At high-flow rates in finer-textured soils the use of a constant (θ) over bar results in underestimation of the time for the wetting front to reach a particular radius. The value of (θ) over bar is related to the time at which the wetting front reaches a given radius. In coarse-textured soils the use of a constant value of (θ) over bar can result in an error of the time when the wetting front reaches a particular radius, as large as 80% at low-flow rates and large radii

Bulk matter physics and its future at the Large Hadron Collider

Measurements at low transverse momentum will be performed at the LHC for studying particle production mechanisms in $pp$ and heavy-ion collisions. Some of the experimental capabilities for bulk matter physics are presented, focusing on tracking elements and particle identification. In order to anticipate the study of baryon production for both colliding systems at multi-TeV energies, measurements for identified species and recent model extrapolations are discussed. Several mechanisms are expected to compete for hadro-production in the low momentum region. For this reason, experimental observables that could be used for investigating multi-parton interactions and help understanding the "underlying event" content in the first $pp$ collisions at the LHC are also mentioned.Comment: 6 pages, 7 figures. To appear in the proceedings of Hot Quarks 2008, Estes Park, Colorado, 18-23 August 200

The MPFI Library: Towards IEEE 1788-2015 Compliance

International audienceThe IEEE 1788-2015 has standardized interval arithmetic. However, few libraries for interval arithmetic are compliant with this standard. The main features of the IEEE 1788-2015 standard are detailed, namely the structure into 4 levels, the possibility to accomodate a new mathematical theory of interval arithmetic through the notion of flavor, and the mechanism of decoration for handling exceptions. These features were not present in the libraries developed prior to the elaboration of the standard. MPFI is such a library: it is a C library, based on MPFR, for arbitrary precision interval arithmetic. MPFI is not (yet) compliant with the IEEE 1788-2015 standard for interval arithmetic: the planned modifications are presented. Some considerations about performance and HPC on interval computations based on this standard, or on MPFI, conclude the paper

Symbolic Methods for Solving Algebraic Systems of Equations and Applications for Testing the Structural Stability

International audienceIn this work, we provide an overview of the classical symbolic techniques for solving algebraic systems of equations and show the interest of such techniques in the study of some problems in dynamical system theory, namely testing the structural stability of multidimensional systems

The CERN Neutrino beam to Gran Sasso (NGS)

The conceptual technical design of the NGS (CERN neutrino beam to Gran Sasso) facility has been presented in the report CERN 98-02 / INFN-AE/98-05. Additional information, in particular an update on various neutrino beam options for the NGS facility, has been provided in a memorandum to the CERN-SPSC Committee (CERN-SPSC/98-35). In the present report, further improvements on the NGS design and performance, in particular new scenarios for SPS proton cycles for NGS operation and a new version of the NGS "high energy" neutrino beam for nt appearance experiments, are described. This new NGS reference beam is estimated to provide three times more nt events per year than the beam presented in the 1998 report. The radiological aspects of the NGS facility have been re-examined with the new beam design. An updated version of the construction schedule is also presented

Charge separation relative to the reaction plane in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}= 2.76 TeV

Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range $|\eta| < 0.8$ are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge dependent azimuthal correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286