Ricerche di supersimmetria con il rivelatore ATLAS

The search for light supersymmetric partners of the top quark (stop squark) could result into the early discovery of physics beyond the Standard Model at the LHC. In this thesis, an analysis based on ATLAS simulated data is presented to study the possibility to discover scalar top quarks at the LHC. A benchmark model in the framework of the Minimal Supersymmetric Standard Model is considered, with a stop squark lighter than the top quark, yielding a final state similar to the one for $tar{t}$ production. We demonstrate that a significant excess of signal events can be extracted with 2 fb-1 of data obtained with the parametrized detector simulation. A technique to subtract the SM background based on the data is developed to achieve this result. The detailed detector simulation has also been used to study trigger and detector effects, confirming the possibility to subtract the background from the data

VERT-X: VERTical X-ray raster-scan facility for ATHENA calibration. The concept design

Calibration of the ATHENA telescope is a critical aspect of the project and raises significant difficulties due to the unprecedented size, mass and focal length of the mirror assembly. The VERT-X project, financed by ESA and started in January 2019 by a Consortium led by INAF and which includes EIE, Media Lario Technologies, GPAP, and BCV Progetti, aims to design an innovative calibration facility. In the VERT-X design the parallel beam, needed for calibration, is produced placing a source in the focus of an X-ray collimator. This system is mounted on a raster-scan mechanism which covers the entire ATHENA optics. The compactness of the VERT-X design allows a vertical geometry for the ATHENA calibration facility, with several potential benefits with respect to the long horizontal tube calibration facilities

Supersymmetry searches in two-lepton plus missing transverse energy channel based on a flavour subtraction technique with the ATLAS detector at the LHC

Supersymmetry searches in two-lepton plus missing transverse energy channel based on a flavour subtraction technique with the ATLAS detector at the LH

Search for Diphoton Events with Large Missing Transverse Energy with 36 pb-1 of 7 TeV Proton-Proton Collision Data with the ATLAS Detector

the search for di-photon events has shown no events excess above the SM predictio

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at √s = 7 TeV with the ATLAS detector

the results are in good agreement with the next-to-leading-order QCD prediction

Search for displaced muonic lepton jets from light Higgs boson decay in proton–proton collisions at √s = 7 TeV with the ATLAS detector

A search is performed for collimated muon pairs displaced from the primary vertex produced in the decay of long-lived neutral particles in proton–proton collisions at √ s = 7 TeV centre-of-mass energy, with the ATLAS detector at the LHC. In a 1.9 fb−1event sample collected during 2011, the observed data are consistent with the Standard Model background expectations. Limits on the product of the production cross section and the branching ratio of a Higgs boson decaying to hidden-sector neutral long-lived particles are derived as a function of the particles’ mean lifetime

Search for anomalous production of prompt like-sign lepton pairs at √s=7 TeV with the ATLAS detector

An inclusive search for anomalous production of two prompt, isolated leptons with the same electric charge is presented. The search is performed in a data sample corresponding to 4.7 fb−1 of integrated luminosity collected in 2011 at √s = 7TeV with the ATLAS detector at the LHC. Pairs of leptons (e±e±, e±μ±, and μ±μ±) with large transverse momentum are selected, and the dilepton invariant mass distribution is examined for any deviation from the Standard Model expectation. No excess is found, and upper limits on the production cross section of like-sign lepton pairs from physics processes beyond the Standard Model are placed as a function of the dilepton invariant mass within a fiducial region close to the experimental selection criteria. The 95% confidence level upper limits on the cross section of anomalous e±e±, e±μ±, or μ±μ± production range between 1.7 fb and 64 fb depending on the dilepton mass and flavour combination