Universal Unitarity Triangle and Physics Beyond the Standard Model

We make the simple observation that there exists a universal unitarity triangle for all models, like the SM, the Two Higgs Doublet Models I and II and the MSSM with minimal flavour violation, that do not have any new operators beyond those present in the SM and in which all flavour changing transitions are governed by the CKM matrix with no new phases beyond the CKM phase. This universal triangle can be determined in the near future from the ratio (Delta M)_d/(Delta M)_s and sin(2 beta) measured first through the CP asymmetry in B_d^0 to psi K_S and later in K to pi nu nubar decays. Also suitable ratios of the branching ratios for B to X_{d,s} nu nubar and B_{d,s} to mu^+ mu^- and the angle gamma measured by means of CP asymmetries in B decays can be used for this determination. Comparison of this universal triangle with the non-universal triangles extracted in each model using epsilon, (Delta M)_d and various branching ratios for rare decays will allow to find out in a transparent manner which of these models, if any, is singled out by experiment. A virtue of the universal triangle is that it allows to separate the determination of the CKM parameters from the determination of new parameters present in the extensions of the SM considered here.Comment: 12 pages, 1 figur

Do methanethiol adsorbates on the Au(111) surface dissociate?

The interaction of methanethiol molecules CH$_{3}$SH with the Au(111) surface is investigated, and it is found for the first time that the S-H bond remains intact when the methanethiol molecules are adsorbed on the regular Au(111) surface. However, it breaks if defects are present in the Au(111) surface. At low coverage, the fcc region is favored for S atom adsorption, but at saturated coverage the adsorption energies at various sites are almost iso-energetic. The presented calculations show that a methanethiol layer on the regular Au(111) surface does not dimerize.Comment: 4 pages, 2 figures, 4 tables, submitted to Phys. Rev. Let

The doctor's sports bag

No Abstract

For banks, fair value adjustments do infl uence dividend policy

Most researchers who investigate the interplay between fair value accounting (FVA) and the fi nancial  crisis look at the time period during the crisis. This paper investigates a potential role for FVA prior to the crisis: If FVA led to increased accounting profi ts with the recognition of transitory gains through profi t and loss during the boom, and if those increased profi ts provided the rationale for increased dividends, then bank capital became riskier prior to the crisis, and this would have made the system more prone to  failure. A study by Goncharov and Van Triest (2011) found no empirical support for an increase in dividends in response to unrealised positive fair value adjustments to income. In contrast, when the setting is  limited to only South African banks, this paper fi nds that South African banks did pay dividends from unrealised transitory gains. This fi nding is based on a combination of three strands of evidence: a panel  regression of the annual dividends declared by the large South African universal banks that showed that those banks probably ignored the unrealised nature of FVA profi ts when dividends were determined;  monthly data from the total South African bank system in a co-integrated regression that showed that  unrealised fair value profi ts from the banking book raised the average level of bank profi ts materially; and simple descriptive statistics on distributions that showed that South African banks distributed a greater  proportion of profi ts during the critical period of 2004 to 2008 when unrealised fair value profi ts from the banking book raised the level of bank profi ts. The fi nding that South African banks did pay dividends from unrealised transitory gains was also confirmed by bank representatives and the post-fi nancial crisis disclosure of one of the South African banks.Key words: fair value accounting, dividend policy, earnings persistence, bank

The lattice of quasi-uniformities

Includes bibliographical references.Over the last thirty years much progress has been made in the investigation of the lattice of uniformities on a set X. In particular, Pelant, Reiterman, Rodl and Simon have published several articles concerning anti-atoms and complements in this lattice. The aim of this dissertation is to begin a similar investigation into the lattice of quasi-uniformities θ(X) on a set X. It starts off with a summary of results obtained for the lattice of topologies on X, which, having been studied in great detail in the past, is intended as an example as to what may be achieved with θ(X). An exposit ion of the lattice of uniformities is then given. We conclude by commencing an investigation into the lattice of quasi-uniformities on X . Where possible, results obtained for the lattice of uniformities are generalized to θ(X), and some original results for θ(X) are also presented

2-Dust : a Dust Radiative Transfer Code for an Axisymmetric System

We have developed a general purpose dust radiative transfer code for an axisymmetric system, 2-Dust, motivated by the recent increasing availability of high-resolution images of circumstellar dust shells at various wavelengths. This code solves the equation of radiative transfer following the principle of long characteristic in a 2-D polar grid while considering a 3-D radiation field at each grid point. A solution is sought through an iterative scheme in which self-consistency of the solution is achieved by requiring a global luminosity constancy throughout the shell. The dust opacities are calculated through Mie theory from the given size distribution and optical properties of the dust grains. The main focus of the code is to obtain insights on (1) the global energetics of dust grains in the shell (2) the 2-D projected morphologies that are strongly dependent on the mixed effects of the axisymmetric dust distribution and inclination angle of the shell. Here, test models are presented with discussion of the results. The code can be supplied with a user-defined density distribution function, and thus, is applicable to a variety of dusty astronomical objects possessing the axisymmetric geometry.Comment: To be published in ApJ, April 2003 issue; 13 pages, 4 tables, 17 figures, 5-page appendix (no figures for the main text included in this preprint). For the complete preprint and code distribution, contact the author

Six Years of ScoX-1 Monitoring with BeppoSAX Wide Field Cameras

We performed a systematic analysis of 54 Wide Field Camera (WFC) observations of ScoX-1 available in the BeppoSAX public archive. Observations span over the six years of BeppoSAX mission lifetime and include 690 hr of data. We searched for shifts and shape changes of the Z pattern in the color-color diagrams. We find that the Z pattern occupies most of the time the same locus in the color-color diagram. There are however a few exceptions, which are discussed in detail.Comment: 4 Pages, 4 figures. To appear in Proc. of the BeppoSAX Symposium: "The Restless High-Energy Universe", E.P.J. van den Heuvel, J.J.M. in 't Zand, and R.A.M.J. Wijers (Eds

Drivers of land use change and household determinants of sustainability in smallholder farming systems of Eastern Uganda

Smallholder farming systems in sub-Saharan Africa have undergone changes in land use, productivity and sustainability. Understanding of the drivers that have led to changes in land use in these systems and factors that influence the systems’ sustainability is useful to guide appropriate targeting of intervention strategies for improvement. We studied low input Teso farming systems in eastern Uganda from 1960 to 2001 in a place-based analysis combined with a comparative analysis of similar low input systems in southern Mali. This study showed that policy-institutional factors next to population growth have driven land use changes in the Teso systems, and that nutrient balances of farm households are useful indicators to identify their sustainability. During the period of analysis, the fraction of land under cultivation increased from 46 to 78%, and communal grazing lands nearly completely disappeared. Cropping diversified over time; cassava overtook cotton and millet in importance, and rice emerged as an alternative cash crop. Impacts of political instability, such as the collapse of cotton marketing and land management institutions, of communal labour arrangements and aggravation of cattle rustling were linked to the changes. Crop productivity in the farming systems is poor and nutrient balances differed between farm types. Balances of N, P and K were all positive for larger farms (LF) that had more cattle and derived a larger proportion of their income from off-farm activities, whereas on the medium farms (MF), small farms with cattle (SF1) and without cattle (SF2) balances were mostly negative. Sustainability of the farming system is driven by livestock, crop production, labour and access to off-farm income. Building private public partnerships around market-oriented crops can be an entry point for encouraging investment in use of external nutrient inputs to boost productivity in such African farming systems. However, intervention strategies should recognise the diversity and heterogeneity between farms to ensure efficient use of these external inputs

Crossing the `Yellow Void' -- Spatially Resolved Spectroscopy of the Post- Red Supergiant IRC+10420 and Its Circumstellar Ejecta

IRC +10420 is one of the extreme hypergiant stars that define the empirical upper luminosity boundary in the HR diagram. During their post--RSG evolution, these massive stars enter a temperature range (6000-9000 K) of increased dynamical instability, high mass loss, and increasing opacity, a semi--forbidden region, that de Jager and his collaborators have called the `yellow void'. We report HST/STIS spatially resolved spectroscopy of IRC +10420 and its reflection nebula with some surprising results. Long slit spectroscopy of the reflected spectrum allows us to effectively view the star from different directions. Measurements of the double--peaked Halpha emission profile show a uniform outflow of gas in a nearly spherical distribution, contrary to previous models with an equatorial disk or bipolar outflow. Based on the temperature and mass loss rate estimates that are usually quoted for this object, the wind is optically thick to the continuum at some and possibly all wavelengths. Consequently the observed variations in apparent spectral type and inferred temperature are changes in the wind and do not necessarily mean that the underlying stellar radius and interior structure are evolving on such a short timescale. To explain the evidence for simultaneous outflow and infall of material near the star, we propose a `rain' model in which blobs of gas condense in regions of lowered opacity outside the dense wind. With the apparent warming of its wind, the recent appearance of strong emission, and a decline in the mass loss rate, IRC +10420 may be about to shed its opaque wind, cross the `yellow void', and emerge as a hotter star.Comment: To appear in the Astronomical Journal, August 200