First-principles calculations and bias-dependent STM measurements at the alpha-Sn/Ge(111) surface: a clear indication for the 1U2D configuration

The nature of the alpha-Sn/Ge(111) surface is still a matter of debate. In particular, two possible configurations have been proposed for the 3x3 ground state of this surface: one with two Sn adatoms in a lower position with respect to the third one (1U2D) and the other with opposite configuration (2U1D). By means of first-principles quasiparticle calculations we could simulate STM images as a function of bias voltage and compare them with STM experimental results at 78K, obtaining an unambiguous indication that the stable configuration for the alpha-Sn/Ge(111) surface is the 1U2D. The possible inequivalence of the two down Sn adatoms is also discussed.Comment: Submitted to PR

Search for Higgs Bosons in SUSY Cascade Decays and Neutralino Dark Matter

The Minimal Supersymmetric Extension of the Standard Model (MSSM) is a well motivated theoretical framework, which contains an extended Higgs sector, including a light Higgs with Standard Model-like properties in most of the parameter space. Due to the large QCD background, searches for such a Higgs, decaying into a pair of bottom quarks, is very challenging at the LHC. It has been long realized that the situation may be ameliorated by searching for Higgs bosons in supersymmetric decay chains. Moreover, it has been recently suggested that the bobber decay channel may be observed in standard production channels by selecting boosted Higgs bosons, which may be easily identified from the QCD background. Such boosted Higgs bosons are frequent in the MSSM, since they are produced from decays of heavy colored supersymmetric particles. Previous works have emphasized the possibility of observing boosted Higgs bosons in the light higgsino region. In this work, we study the same question in the regions of parameter space consistent with a neutralino dark matter relic density, analyzing its dependence on the non-standard Higgs boson, slepton and squark masses, as well as on the condition of gaugino mass unification. In general, we conclude that, provided sleptons are heavier than the second lightest neutralinos, the presence of boosted Higgs is a common MSSM feature, implying excellent prospects for observation of the light MSSM Higgs boson in the near future.Comment: 30 pages, 9 figures. v2: New Xenon 100 results implemented, version to appear in PR

Percezioni paesistico-ambientali nelle microfiliere di qualit\ue0 (Farmers and Landscape: Environmental Perceptions in Quality Micro-Chains)

Among the phenomena of transition from useless to useful in the landscape-cultural mosaic is that of the farmers\u2019 changing perceptions of the environment and the creation of externalities to their micro-chain underlying business, or those of others. The objective of this study is to verify whether there is a connection between those perceptions and the management classes of their farms, in regards to both environmental aspects and to their participation in joint initiatives. From the statistical analysis of 30 FVG micro-chains, it was found that multi-active advanced farms perceive most of the improvements that are derived from their activities or the activities of others. Additionally, their willingness to engage in joint-initiatives is significant in certain aspects. Whereas amateur farmers are sceptical about their ability to positively affect the landscape and the environment, conventional farmers are much more confident that their own actions are more effective than those of others. In regards to joint initiatives, neither conventional nor amateur farmers are at all willing to engage in the collection and disposal of waste, whilst they do appear to be more positive in relation to territorial branding and, moderately, to retail stores