170390949
Recherche de production resonante de sleptons au run I de D0 & identification et mesure des electrons au run II
Une recherche de production resonante de particules supersymetrique (smuon et sneutrino du muon) est presentee. Le cadre theorique de cette etude est le modele msugra, ou on considere cinq parametres libres : m 0, m 1 / 2, tan, a 0, sign(), avec r-parite violee (un parametre). Deux methodes d'analyse ont ete appliquees : l'analyse sequentielle consideree comme une methode traditionnelle et l'analyse par reseau de neurones qui est de plus en plus utilisee comme outil en physique des particules. Notre etude est basee sur les donnees du run i de l'experience d aupres du tevatron a fermilab (usa). La luminosite consideree est de 94pb 1. Aucun exces par rapport aux predictions du modele standard n'a ete observe, on interprete par consequent ce resultat en termes de limites sur les parametres du modele utilise. Des contours d'exclusion a 95% de niveau de confiance dans le plan (m 0, m 1 / 2) sont donnes. Des valeurs de m 0 et m 1 / 2 jusqu'a 230 gev et 260 gev sont exclues pour une constante de couplage 2 1 1 = 0. 09, tan = 2, sign () = 1 et a 0 = 0. On peut aussi interpreter ce resultat par des contours d'exclusion dans les plans des masses, (m , m x 10) par exemple, ou est le sneutrino du muon et x 0 1 est le neutralino le plus leger. Des masses (relatives) du et x 0 1 de 280 gev et 112gev sont exclues a 95% de niveau de confiance. Cette meme analyse peut etre refaite sur les donnees du run ii qui beneficie d'une plus grande luminosite instantanee (5. 2 10 3 2 cm 2s 1 au run ii contre 0. 86 10 3 2 cm 2s 1 au run i) et une plus grande energie dans le centre de masse (2tev contre un 1. 8tev au run i). Cela permettra de restreindre d'avantage les parametres de msugra et comme consequence les masses des particules supersymetriques. Une autre partie de ce travail traite de l'identification de l'electron au run ii qui est tres importante pour la recherche d'une nouvelle physique. Plusieurs outils sont utilises pour une telle fin. Particulierement nous avons etudie les performances de la matrice de covariance (matrice h).
9626406
The detector control system for the ATLAS semiconductor tracker assembly phase
The ATLAS Semiconductor tracker (SCT) consists of 4088 silicon microstrip modules, with a total of 6.3 million readout channels. These are arranged into 4 concentric barrel layers and 2 endcaps of 9 disks each. The coherent and safe operation of the SCT during commissioning and subsequent operation is an essential task of the Detector Control System (DCS). The main building blocks of the SCT DCS, the cooling system, the power supplies and the environmental system, are described. First results from DCS testing are presented.
120192224
Measurements of sigma(e^+ e^- -> Upsilon(nS)pi^+pi^-) and sigma(e^+ e^- -> b bbar) in the Upsilon(10860) and Upsilon(11020) resonance regions
110275378
The control and monitoring system for the ATLAS semi-conductor tracker
Abstract The ATLAS Semi-Conductor Tracker (SCT) will be made of 4088 silicon modules mounted on four barrel supports and eighteen end cap disks. At present module production has started in different sites all around the world. The assembly of the modules into the support structures is taking place at three different macro-assembly sites. To allow for the safety operation of the detector a Detector Control System (DCS) is being developed at CERN that will be close to the final ATLAS configuration. The DCS will control and monitor the power supply provided to the modules, the cooling system and the environmental variables. This paper will give an overview of the system required to operate and readout large-scale silicon detectors.
18388560
A Complete Renormalization Group Trajectory Between Two Fixed Points
We give a rigorous nonperturbative construction of a massless discrete trajectory for Wilson’s exact renormalization group. The model is a three dimensional Euclidean field theory with a modified free propagator. The trajectory realizes the mean field to critical crossover from the ultraviolet Gaussian fixed point to an analog recently constructed by Brydges, Mitter and Scoppola of the Wilson-Fisher nontrivial fixed point.
16110261
A physicist's proof of the Lagrange?Good multivariable inversion formula
We provide a new proof, inspired by quantum field theory, of the Lagrange--Good multivariable inversion formula.
17032794
Bosonic Monocluster Expansion
Abstract: We compute Green's functions of a Bosonic field theory with cutoffs by means of a “minimal” expansion which in a single move, interpolating a generalized propagator, performs the usual tasks of the cluster and Mayer expansion. In this way it allows a direct construction of the infinite volume or thermodynamic limit and it brings constructive Bosonic expansions closer to constructive Fermionic expansions and to perturbation theory.
5900178
An Explicit Large Versus Small Field Multiscale Cluster Expansion
We introduce a new type of cluster expansion which generalizes a previous formula of Brydges and Kennedy. The method is especially suited for performing a phase-space multiscale expansion in a just renormalizable theory, and allows the writing of explicit non-perturbative formulas for the Schwinger functions. The procedure is quite model independent, but for simplicity we chose the infrared $\ph^4_4$ model as a testing ground. We used also a large field versus small field expansion. The polymer amplitudes, corresponding to graphs without almost local two and for point functions, are shown to satisfy the polymer bound.