From weak-scale observables to leptogenesis

Thermal leptogenesis is an attractive mechanism for generating the baryon asymmetry of the Universe. However, in supersymmetric models, the parameter space is severely restricted by the gravitino bound on the reheat temperature $T_{RH}$. For hierarchical light neutrino masses, it is shown that thermal leptogenesis {\it can} work when $T_{RH} \sim 10^{9}$ GeV. The low-energy observable consequences of this scenario are $BR(\tau \to \ell \gamma) \sim 10^{-8} - 10^{-9}$. For higher $T_{RH}$, thermal leptogenesis works in a larger area of parameter space, whose observable consequences are more ambiguous. A parametrisation of the seesaw in terms of weak-scale inputs is used, so the results are independent of the texture chosen for the GUT-scale Yukawa matrices.Comment: a few references adde

Modelling Jets, Tori and Flares in Pulsar Wind Nebulae

In this contribution we review the recent progress in the modelling of Pulsar Wind Nebulae (PWN). We start with a brief overview of the relevant physical processes in the magnetosphere, the wind-zone and the inflated nebula bubble. Radiative signatures and particle transport processes obtained from 3D simulations of PWN are discussed in the context of optical and X-ray observations. We then proceed to consider particle acceleration in PWN and elaborate on what can be learned about the particle acceleration from the dynamical structures called GwispsG observed in the Crab nebula. We also discuss recent observational and theoretical results of gamma-ray flares and the inner knot of the Crab nebula, which had been proposed as the emission site of the flares. We extend the discussion to GeV flares from binary systems in which the pulsar wind interacts with the stellar wind from a companion star. The chapter concludes with a discussion of solved and unsolved problems posed by PWN

A novel mechanism of spheroidal weathering: a case study from the Monchepluton layered complex, Kola Peninsula, Russia

We describe an unusual pattern of spheroidally weathered surface developed in a mineralized harzburgite of Mount Kumuzhya, Monchepluton layered complex of Early Proterozoic age, Kola Peninsula, Russia. This rock is composed of a matrix and spheroids, which differ in their paragenesis and textures. The relief spheroids consist principally of large oikocrysts (up to 3-4 cm) of orthopyroxene (En86), enclosing aggregates of finegrained chromian spinel (chromite-magnesiochromite). The matrix is mostly composed of olivine (Fo90.5), surrounded by patches of chromite. We infer that this pattern represents a new variety of spheroidal weathering of rock surface, which is not related to “normal” spheroidal weathering. Presumably, it has resulted mainly from the primary magmatic characteristics, whereas other factors, such as differential rates of weathering of olivine and orthopyroxene, were of secondary importance

The structure and cryptic layering of the Pados-Tundra ultramafic complex, Serpentinite belt, Kola Peninsula, Russia

The Paleoproterozoic Pados-Tundra ultramafic complex, ~6 x 1.5-2.1 km in size and ~2.1 Ga in age, located in the Kola Peninsula of Russia, is the main representative of the Serpentinite belt in the northern Fennoscandian Shield. It is composed of fragmented or foliated bodies of dunite-harzburgite-orthopyroxenite; these have an elevated potential for Cr and the platinum-group elements (PGE). In general, the complex consists of the Dunite Zone (olivine cumulates) and Orthopyroxenite Zone (orthopyroxene + olivine cumulates, interlayered); its upper zones of more evolved rocks of mafic compositions appear to have been removed by erosion. The complex shows well-recognized patterns of cryptic layering, documented along cross-sections in grains of olivine and Ca-poor pyroxene. Narrow ranges of high-Mg compositions are observed in olivine [Fo85.5-90.6] and orthopyroxene [Wo<0.1-3.0En85.1-91.2Fs8.1-12.5]. Their trends of crystallization indicate that cumulate olivine, orthopyroxene, and olivine-orthopyroxene rocks (dunite and orthopyroxenite, with subordinate harzburgite and olivine-bearing orthopyroxenite) become, in general, more evolved toward the internal portions of the complex; stratigraphically lower and early-crystallizing cumulates are exposed closer to its outer contact. The compositions of early phases of cumulus origin, Fo91 olivine and En91, orthopyroxene are notably magnesian, implying an elevated Mg# in the parental magma. The anomalously Cr-Al-rich grains of serpentine (up to ~2.5 wt.% Cr2O3 and ~4.0 wt.% Al2O3), hitherto unreported, are present in specimens of dunite near the northeastern margin of the complex. Supercooling and metastable crystallization likely affected the melt in the eastern portion of the complex near the Dunite block (i.e., host for segregations and stratiform-like layers of chromitite) and relatively close to the outer contact. An uncommon mineralization of the PGE is associated with the chromitite deposits at Pados-Tundra