Andrea Viceré

Radiative correction effects of a very heavy top

Abstract If the top is very heavy, mt ⪢ Mz, the dominant radiative correction effects in all electroweak precision tests can be exactly characterized in terms of two quantities, the ϱ-mparameter and the GIM-violating Z → b b coupling. These quantities can be computed using the standard model lagrangian with vanishing gauge couplings. This is done here up to two loops for arbitrary values of the Higgs mass.

Two loop heavy top effects in the Standard Model

Abstract We give a detailed description of the calculation in the Standard Model of all the m t 4 radiative correction effects to the electroweak precision observables for arbitrary values of the Higgs mass.

QCD corrections to the weak radiative B-meson decay

Abstract The B → X s γ decay, which is sensitive to the top-quark mass, has become now particularly interesting as we expect a t-mass greater than 80 GeV. The QCD corrections play a relevant role, enhancing the GIM suppressed vertex: their computation presents many technical difficulties, which have led to different results in the previous literature. We have performed the calculation off-shell, in all gauges, in the leading logarithmic approximation; we confirm the strong enhancement of the QCD corrected branching ratios.

The b→sγ decay revisited

Abstract In this work we compute the leading logarithmic corrections to the b→sγ decay in a dimensional scheme which does not require any definition of the γ5 matrix. The scheme does not exhibit unconsistencies and it is therefore a vaible alternative to the t Hooft Veltman scheme, particularly in view of the next-to-leading computation. We confirm the recent results of Ciuchini et al.

QCD corrections to the B→Xse+e− decay

Abstract We have evaluated the short distance QCD corrections to the B→X s e + e − process in a quark spectator model within an effective hamiltonian framework. The dependence of the rate on the top-quark mass is examined in the minimal standard model. We have found a light suppression of the differential width for a large invariant mass of the e + e − pair; the integrated width is slightly enhanced.

High-performance road-vehicle optimised aerodynamic design: Application of parallel computing to car design

Abstract The HIPEROAD project has developed a software system capable of performing a semi-automatic optimisation of the shape of sport cars with respect to their aerodynamical properties. The system utilises an aerodynamic solver implemented on parallel MIMD systems, and features advanced tools for the evolution and meshing of car surfaces. The system allows one to include aerodynamic optimisation in the early stages of car design. It has been tested on a Ferrari auto model and full agreement between computed and measured aerodynamical properties was found. The code has been used for designing an optimised model with improved car safety.

IDENTIFICATION AND MONITORING OF VIOLIN MODES USING THE KARHOUNEN–LOÈVE TRANSFORM

The Karhounen–Loeve(K-L) transform is used as a method to analyze the simulated thermal noise of a simple suspension system. Added to this noise are impulses which are supposed to mimic the effect of creep events in the suspension wires. The K-L transform allows us to identify the internal modes of the suspensions wires (the so-called violin modes), and then monitor their excitation to look for these impulsive events.

HIgh PErformance ROADvehicle Optimized Aerodynamic Design: Application of Parallel Computing to Car Design

The HIPEROAD project has developed a software system capable of performing a semi-automatic optimisation of the shape of sport cars with respect to their aerodynamical properties. The system utilises an aerodynamic solver implemented on parallel MIMD systems, and features advanced tools for the evolution and meshing of car surfaces. The system allows to include aerodynamic optimisation in the early stages of car design. It has been tested on a Ferrari Auto model and full agreement between computed and measured aerodynamical properties was found. The code has been used for designing an optimised model with improved car safety, reducing the vertical upload significantly without affecting car performance.

Validation and Performance Analysis of a Parallel Ported Code for Simulating the Effects of Lightning Strokes on Telecommunication Buildings

The Artemis subproject, in the framework of the UE Capri project, deals with porting on parallel architectures of a Method of Moment (MoM) code for electromagnetic design and hardening of telecommunication centres against the effects of lightning strokes. After a preliminary stage of the work during which QR and LU algorithms for large complex matrix inversion were implemented both on Alenias Quadrics (SIMD) and Cray T3D (MIMD) platforms, in order to choose the best suitable machine for such a kind of problem, the code has been ported on the last one. In this paper the parallel code validation and the performance improvement analysis with respect to the sequential one will be reported and discussed.

Triggering and data analysis for the VIRGO experiment on the APEmille parallel computer

We give a brief resume of some possible strategies for the real-time data analisys in the framework of the VIRGO experiment. We discuss in particular the utility and the feasibility of their implementation on parallel computers, focusing on the APEmille SIMD machine. We evaluate the computational power required in two cases: the monitoring of known pulsars and the detection of binary coalescences.