Search for Higgs Bosons Decay H→γγH\to \gamma\gamma Using Vector Boson Fusion

The sensitivity of the ATLAS experiment to low mass SM Higgs produced via Vector Boson Fusion mechanism with $H\to \gamma\gamma$ is invest igated. A cut based event selection has been chosen to optimize the expected signal significance with this decay mode. A signal significance of 2. 2$\sigma$ may be achieved for M_H=130 \gev with 30 fb$^{-1}$ of accumulated luminosity

Reconstruction subgrid models for nonpremixed combustion

Large-eddy simulation of combustion problems involves highly nonlinear terms that, when filtered, result in a contribution from subgrid fluctuations of scalars, Z, to the dynamics of the filtered value. This subgrid contribution requires modeling. Reconstruction models try to recover as much information as possible from the resolved field Z, based on a deconvolution procedure to obtain an intermediate field ZM. The approximate reconstruction using moments (ARM) method combines approximate reconstruction, a purely mathematical procedure, with additional physics-based information required to match specific scalar moments, in the simplest case, the Reynolds-averaged value of the subgrid variance. Here, results from the analysis of the ARM model in the case of a spatially evolving turbulent plane jet are presented. A priori and a posteriori evaluations using data from direct numerical simulation are carried out. The nonlinearities considered are representative of reacting flows: power functions, the dependence of the density on the mixture fraction (relevant for conserved scalar approaches) and the Arrhenius nonlinearity (very localized in Z space). Comparisons are made against the more popular beta probability density function (PDF) approach in the a priori analysis, trying to define ranges of validity for each approach. The results show that the ARM model is able to capture the subgrid part of the variance accurately over a wide range of filter sizes and performs well for the different nonlinearities, giving uniformly better predictions than the beta PDF for the polynomial case. In the case of the density and Arrhenius nonlinearities, the relative performance of the ARM and traditional PDF approaches depends on the size of the subgrid variance with respect to a characteristic scale of each function. Furthermore, the sources of error associated with the ARM method are considered and analytical bounds on that error are obtained

Prospects for Higgs Searches via VBF at the LHC with the ATLAS Detector

We report on the potential for the discovery of a Standard Model Higgs boson with the vector boson fusion mechanism in the mass range 115 with the ATLAS experiment at the LHC. Feasibility studies at hadron level followed by a fast detector simulation have been performed for H\to W^{(*)}W^{(*)}\to l^+l^-\sla{p_T}, $H\to\gamma\gamma$ and $H\to ZZ\to l^+l^-q\bar{q}$. The results obtained show a large discovery potential in the range 115. Results obtained with multivariate techniques are reported for a number of channels.Comment: 14 pages, 4 figures, contributed to 2003 Les Houches Workshop on Physics at TeV Colliders. Incorporated comments from ATLAS referee

Wrinkling of a bilayer membrane

The buckling of elastic bodies is a common phenomenon in the mechanics of solids. Wrinkling of membranes can often be interpreted as buckling under constraints that prohibit large amplitude deformation. We present a combination of analytic calculations, experiments, and simulations to understand wrinkling patterns generated in a bilayer membrane. The model membrane is composed of a flexible spherical shell that is under tension and that is circumscribed by a stiff, essentially incompressible strip with bending modulus B. When the tension is reduced sufficiently to a value \sigma, the strip forms wrinkles with a uniform wavelength found theoretically and experimentally to be \lambda = 2\pi(B/\sigma)^{1/3}. Defects in this pattern appear for rapid changes in tension. Comparison between experiment and simulation further shows that, with larger reduction of tension, a second generation of wrinkles with longer wavelength appears only when B is sufficiently small.Comment: 9 pages, 5 color figure

Classical Topological Order in Kagome Ice

We examine the onset of classical topological order in a nearest-neighbor kagome ice model. Using Monte Carlo simulations, we characterize the topological sectors of the groundstate using a non-local cut measure which circumscribes the toroidal geometry of the simulation cell. We demonstrate that simulations which employ global loop updates that are allowed to wind around the periodic boundaries cause the topological sector to fluctuate, while restricted local loop updates freeze the simulation into one topological sector. The freezing into one topological sector can also be observed in the susceptibility of the real magnetic spin vectors projected onto the kagome plane. The ability of the susceptibility to distinguish between fluctuating and non-fluctuating topological sectors should motivate its use as a local probe of topological order in a variety of related model and experimental systems.Comment: 17 pages, 9 figure

Maintaining security requirements of software systems using evolving crosscutting dependencies

Security requirements are concerned with protecting assets of a system from harm. Implemented as code aspects to weave protection mechanisms into the system, security requirements need to be validated when changes are made to the programs during system evolution. However, it was not clear for developers whether existing validation procedures such as test cases are sufficient for security and when the implemented aspects need to adapt. In this chapter, we propose an approach for detecting any change to the satisfaction of security requirements in three steps: (1) identify the asset variables in the systems that are only accessed by a join-point method; (2) trace these asset variables to identify both control and data dependencies between the non-aspect and aspect functions; and (3) update the test cases ac-cording to implementation of these dependencies to strengthen the protection when a change happens. These steps are illustrated by a case study of a meeting scheduling system where security is a critical concern

Error induced by neglecting subgrid chemical segregation due to inefficient turbulent mixing in regional chemical-transport models in urban environments

We employed direct numerical simulations to esti- mate the error on chemical calculation in simulations with re- gional chemical-transport models induced by neglecting sub- grid chemical segregation due to inefficient turbulent mixing in an urban boundary layer with strong and heterogeneously distributed surface emissions. In simulations of initially seg- regated reactive species with an entrainment-emission con- figuration with an A–B–C second-order chemical scheme, urban surface emission fluxes of the homogeneously emit- ted tracer A result in a very large segregation between the tracers and hence a very large overestimation of the effec- tive chemical reaction rate in a complete-mixing model.The article processing charges for this open- access publication were covered by the Max Planck SocietyPostprint (published version