Asymptotic regimes for hadron diffractive scatterings and Coulomb interaction: Arguments for the black disk mode

Comparative analysis of the interplay of hadron and Coulomb interactions in [Formula: see text] scattering amplitudes is performed in a broad energy interval, [Formula: see text], for two extreme cases: for the asymptotic interactions of hadrons in black disk and resonant disk modes. The interactions are discussed in terms of the [Formula: see text]-matrix function technique. In the asymptotic regime, the real part of the hadronic amplitude is concentrated in both cases on the boundary of the disks in the impact parameter space but the LHC energy region is not asymptotic for the resonant disk mode that lead to a specific interplay of hadronic and Coulombic amplitudes. For the [Formula: see text] scattering at [Formula: see text] an interplay of the hadron and Coulomb interactions in the resonant disk modes is realized in a shoulder in [Formula: see text] at [Formula: see text]. The absence of such a shoulder in the data at 8 TeV can be considered as an argument against the resonant disk mode.

Central production of lepton–antilepton pairs and heavy quark composite states in hadron diffractive collisions at ultrahigh energies

Central production of lepton–antilepton pairs (e+e- and μ+μ-) and heavy quark composite states (charmonia and bottomonia) in diffractive proton collisions (proton momenta transferred |q⊥| ~ m/ ln s) are studied at ultrahigh energies ( ln s ≫ 1), where σ tot (pp±) ~ ln N s with 1 ≲ N ≲ 2. The pp±-rescattering corrections, which are not small, are calculated in terms of the K-matrix approach modified for ultrahigh energies. Two versions of hadron interactions are considered in detail: the growth (i) σ tot (pp±) ~ ln 2 s, σ inel (pp±) ~ ln 2 s within the black disk mode and (ii) σ tot (pp±) ~ ln 2 s, σ inel (pp±) ~ ln s within the resonant disk mode. The energy behavior of the diffractive production processes differs strongly for these modes, thus giving a possibility to distinguish between the versions of the ultrahigh energy interactions.

GRAPHIC: The Geneva Reduction and Analysis Pipeline for High-contrast Imaging of planetary Companions

We present a new analysis and reduction pipeline for the detection of planetary companions using Angular Differential Imaging. The pipeline uses Fourier transforms for image shifting and rotation in order to achieve very low signal loss. Furthermore it is parallelised in order to run on computer clusters of up to 1024 cores. The pipeline was developed in Geneva for the ongoing direct imaging campaign for stars with radial velocity drifts in the HARPS and CORALIE radial-velocity planet-search surveys. In addition to that, a disk mode has been implemented in the context of observations of the protoplanetary disk around HD142527.

Evolution of Supermassive Black Holes

Cosmological simulations describing both the evolution of supermassive black holes and their host galaxies were performed by using the tree PM-SPH code GADGET-2 (Springel 2005). Physical mechanisms affecting the dynamics and the physical conditions of the gas (ionization and cooling processes, local heating by stars, injection of mechanical energy by supernovae, chemical enrichment) were introduced in the present version of the code (Filloux 2009). Black holes in a state of accretion (AGNs) also inject mechanical energy in the surrounding medium, contributing for quenching the star formation activity. In all simulations a ΛCDM cosmology was adopted (h = 0.7, ΩΛ=0.7, Ωm=0.3, Ωb=0.046 and σ8=0.9). Simulations were performed in a volume with a side of 50h−1 Mpc, starting at z = 50 and through the present time (z = 0). For low and intermediate resolution runs, the initial gas mass particles are respectively 5.35× 108M⊙ and 3.09×108M⊙. Black holes (BHs) are represented by collisionless particles and seeds of 100 M⊙ were introduced in density peaks at z = 15, growing either by accretion or coalescence. The accretion rate from the “disk mode” is based on a turbulent viscous thin disk model whereas in the “spherical mode” the rate is given by the Bondi–Hoyle formula. When accreting matter, jets, modeled by conical regions perpendicular to the disk plane, inject kinetic energy into the surrounding medium. Two models were tested: in the first, the injected energy rate is about 10% of the gravitational energy rate released in the accretion process while in the second, the injected energy rate is based on the Blandford & Znajek (1977) mechanism. All simulations give, at z = 0, similar black hole mass function but they overestimate slightly the BH density for masses above ~ 108M⊙. The resulting BH density in this mass range is affected by feedback processes since they control the amount of gas available for accretion. The present simulations are not able to produce very massive BHs (~109M⊙) at z ~ 6. However the evolution of the BH mass density derived from our simulations are in quite good agreement with that derived from the QSO luminosity function. This indicates that our simulations reproduce quite well the average accretion rate history of BHs. Correlations between the BH mass and properties of the host galaxy (velocity dispersion for bulge systems or the stellar mass or the dark halo mass) are also well reproduced. In conclusion, these exploratory simulations reproduce the data at z = 0 quite well. However, the present adopted recipe for the accretion rate in the “disk mode” seems to be inefficient to produce massive BHs as early as z ~ 6. Higher resolution simulations including a new approach for modeling the “disk mode” are presently under way and that particular difficulty is expected to be solved.

An Analysis on Disk Vibration in Steam Turbine

A modal analysis of disk in steam turbine is discussed in this paper. The analysis is performed with two methods: modal analysis of integrated blades-disk and of cyclic symmetric structure with ANSYS. The disk mode shape is summed up in five shapes: the disk vibrates at each nodal diameter with blades vibrating mainly in axial A0 shape, in tangent A0 shape, in twist shape, in tangent A1 shape and the disk vibrates in umbrella shape. Finally a safety assessment about disk vibration is given in the paper.