Top quark production at the LHC

Twenty years past its discovery, the top quark continues attracting great interest as experiments keep unveiling its properties. An overview of the latest measurements in the domain of top quark production, performed by the ATLAS and CMS experiments at the CERN LHC, is given. The latest measurements of top quark production rates via strong and electroweak processes are reported and compared to different perturbative QCD predictions. Fundamental properties, such as the mass or the couplings of the top quark, as well as re-interpretations seeking for beyond the standard model contributions in the top quark sector, are extracted from these measurements. In each case an attempt to highlight the first results and main prospects for the on-going Run 2 of the LHC is made.Comment: Contribution to the proceedings of the 50th Rencontres de Moriond Electroweak session - 201

Technological change, accident prevention and civil liability

The improvement of accident prevention technology in many fields of social life has spurred new challenges to the doctrinal tools of fault and strict based civil liability in the law of torts. Amid these challenges lies the identification of the proper scope of the respective criteria of liability in a changing factual environment, their suitability as doctrinal tools, as well as their actual application to concrete cases given the amount of information which would be needed to render adequate judgments. Precedents and old laws should be assessed with caution, taking into account the tacit cost-benefit analysis embedded in them, for they may or may not serve the interests of welfare maximization in an environment with constantly renewed accident prevention technology

Structural Flyby Characterization of Nanoporosity

Recently, Ferreira da Silva et al. [3] have performed a gradient pattern analysis of a canonical sample set (CSS) of scanning force microscopy (SFM) images of p-Si. They applied the so-called Gradient Pattern Analysis to images of three typical p-Si samples distinguished by different absorption energy levels and aspect ratios. Taking into account the measures of spatial asymmetric fluctuations they interpreted the global porosity not only in terms of the amount of roughness, but rather in terms of the structural complexity (e.g., walls and fine structures as slots). This analysis has been adapted in order to operate in a OpenGL flyby environment (the StrFB code), whose application give the numerical characterization of the structure during the flyby real time. Using this analysis we compare the levels of asymmetric fragmentation of active porosity related to different materials as p-Si and "porous diamond-like" carbon. In summary we have shown that the gradient pattern analysis technique in a flyby environment is a reliable sensitive method to investigate, qualitatively and quantitatively, the complex morphology of active nanostructures

Generalized CP Invariance and the Yukawa sector of Two-Higgs Models

We analyze generalized CP symmetries of two-Higgs doublet models, extending them from the scalar to the fermion sector of the theory. We show that, with a single exception, those symmetries imply massless fermions. The single model which accommodates a fermionic mass spectrum compatible with experimental data possesses a remarkable feature. It displays a new type of spontaneous CP violation, which occurs not in the scalar sector responsible for the symmetry breaking mechanism but, rather, in the fermion sector.Comment: RevTex, 4 pages, no figures Version2: Remarkable additional conclusion => title & text changes; section adde

Activation thresholds in epidemic spreading with motile infectious agents on scale-free networks

We investigate a fermionic susceptible-infected-susceptible model with mobility of infected individuals on uncorrelated scale-free networks with power-law degree distributions $P (k) \sim k^{-\gamma}$ of exponents $2<\gamma<3$. Two diffusive processes with diffusion rate $D$ of an infected vertex are considered. In the \textit{standard diffusion}, one of the nearest-neighbors is chosen with equal chance while in the \textit{biased diffusion} this choice happens with probability proportional to the neighbor's degree. A non-monotonic dependence of the epidemic threshold on $D$ with an optimum diffusion rate $D_\ast$, for which the epidemic spreading is more efficient, is found for standard diffusion while monotonic decays are observed in the biased case. The epidemic thresholds go to zero as the network size is increased and the form that this happens depends on the diffusion rule and degree exponent. We analytically investigated the dynamics using quenched and heterogeneous mean-field theories. The former presents, in general, a better performance for standard and the latter for biased diffusion models, indicating different activation mechanisms of the epidemic phases that are rationalized in terms of hubs or max $k$-core subgraphs.Comment: 9 pages, 4 figure