Next-to-Leading Order NMSSM Decays with CP-odd Higgs Bosons and Stops

We compute the full next-to-leading order supersymmetric (SUSY) electroweak (EW) and SUSY-QCD corrections to the decays of CP-odd NMSSM Higgs bosons into stop pairs. In our numerical analysis we also present the decay of the heavier stop into the lighter stop and an NMSSM CP-odd Higgs boson. Both the EW and the SUSY-QCD corrections are found to be significant and have to be taken into account for a proper prediction of the decay widths.Comment: 28 pages, 10 figure

Veronesean representations of projective spaces over quadratic associative division algebras

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The photophoretic sweeping of dust in transient protoplanetary disks

Context: Protoplanetary disks start their lives with a dust free inner region where the temperatures are higher than the sublimation temperature of solids. As the star illuminates the innermost particles, which are immersed in gas at the sublimation edge, these particles are subject to a photophoretic force. Aims: We examine the motion of dust particles at the inner edge of protoplanetary disks due to photophoretic drag. Methods: We give a detailed treatment of the photophoretic force for particles in protoplanetary disks. The force is applied to particles at the inner edge of a protoplanetary disk and the dynamical behavior of the particles is analyzed. Results: We find that, in a laminar disk, photophoretic drag increases the size of the inner hole after accretion onto the central body has become subdued. This region within the hole becomes an optically transparent zone containing gas and large dusty particles (>>10 cm), but devoid of, or strongly depleted in, smaller dust aggregates. Photophoresis can clear the inner disk of dust out to 10 AU in less than 1 Myr. The details of this clearance depend on the size distribution of the dust. Any replenishment of the dust within the cleared region will be continuously and rapidly swept out to the edge. At late times, the edge reaches a stable equilibrium between inward drift and photophoretic outward drift, at a distance of some tens of AU. Eventually, the edge will move inwards again as the disk disperses, shifting the equilibrium position back from about 40 AU to below 30 AU in 1-2 Myr in the disk model. In a turbulent disk, diffusion can delay the clearing of a disk by photophoresis. Smaller and/or age-independent holes of radii of a few AU are also possible outcomes of turbulent diffusion counteracting photophoresis. Conclusions: This outward and then inward moving edge marks a region of high dust concentration. This density enhancement, and the efficient transport of particles from close to the star to large distances away, can explain features of comets such as high measured ratios of crystalline to amorphous silicates, and has a large number of other applications

Dynamics of thick discs around Schwarzschild-de Sitter black holes

We consider the effects of a cosmological constant on the dynamics of constant angular momentum discs orbiting Schwarzschild-de Sitter black holes. The motivation behind this study is to investigate whether the presence of a radial force contrasting the black hole's gravitational attraction can influence the occurrence of the runaway instability, a robust feature of the dynamics of constant angular momentum tori in Schwarzschild and Kerr spacetimes. In addition to the inner cusp near the black hole horizon through which matter can accrete onto the black hole, in fact, a positive cosmological constant introduces also an outer cusp through which matter can leave the torus without accreting onto the black hole. To assess the impact of this outflow on the development of the instability we have performed time-dependent and axisymmetric hydrodynamical simulations of equilibrium initial configurations in a sequence of background spacetimes of Schwarzschild-de Sitter black holes with increasing masses. The simulations have been performed with an unrealistic value for the cosmological constant which, however, yields sufficiently small discs to be resolved accurately on numerical grids and thus provides a first qualitative picture of the dynamics. The calculations, carried out for a wide range of initial conditions, show that the mass-loss from the outer cusp can have a considerable impact on the instability, with the latter being rapidly suppressed if the outflow is large enough.Comment: 12 pages; A&A, in pres

Photophoresis as a source of hot minerals in comets

A time-dependent model of the solar nebula is used to describe the outward transport of hot mineral aggregates from locations in the warm inner regions of the nebula under the influence of photophoresis. We show that there is a direct dependence between the size of the gap initially assumed to exist in the inner solar nebula and the heliocentric distance to which the aggregates are likely to drift. We demonstrate that, despite a significant contribution to the opacity of the disk resulting from Rayleigh scattering by hydrogen, photophoresis can be considered as a transport mechanism leading to the presence of hot minerals in comets. This mechanism can lead to an influx of hot minerals in the formation regions of the main cometary reservoirs, implying a potential "dust-loading" of bodies from these populations. This scenario is compatible with the detection of crystalline silicates in a growing number of comets and also with the recent identification of CAIs in the samples returned from Comet 81P/Wild 2 by the Stardust mission. Finally, we find that this mechanism is consistent with the compositional diversity observed in small bodies of the outer solar system, in contrast to other proposed processes which invoke an efficient turbulent mixing within the primordial nebula