Professor Daniela Bortoletto

Abstract:

Measurements of integrated and differential cross-sections for electroweak W±Z production in association with two jets (W±Zjj) in proton-proton collisions are presented. The data collected by the ATLAS detector at the Large Hadron Collider from 2015 to 2018 at a centre-of-mass energy of s = 13 TeV are used, corresponding to an integrated luminosity of 140 fb−1. The W±Zjj candidate events are reconstructed using leptonic decay modes of the gauge bosons. Events containing three identified leptons, either electrons or muons, and two jets are selected. Processes involving pure electroweak W±Zjj production at Born level are separated from W±Zjj production involving a strong coupling. The measured integrated fiducial cross-section of electroweak W±Zjj production per lepton flavour is σWZjj−EW→ℓ′νlljj = 0.368 ± 0.037 (stat.) ± 0.059 (syst.) ± 0.003 (lumi.) fb, where ℓ and ℓ′ are either an electron or a muon. Respective cross-sections of electroweak and strong W±Zjj production are measured separately for events with exactly two jets or with more than two jets, and in three bins of the invariant mass of the two jets. The inclusive W±Zjj production cross-section, without separating electroweak and strong production, is also measured to be σWZjj→ℓ′νlljj = 1.462 ± 0.063 (stat.) ± 0.118 (syst.) ± 0.012 (lumi.) fb, per lepton flavour. The inclusive W±Zjj production cross-section is measured differentially for several kinematic observables. Finally, the measurements are used to constrain anomalous quartic gauge couplings by extracting 95% confidence level intervals on dimension-8 operators.

Abstract:

The MALTA family of Depleted Monolithic Active Pixel Sensors (DMAPS) is produced using Tower 180 nm CMOS technology, specifically targeting radiation-hard applications in the HL-LHC and beyond. Several process modifications have resulted in radiation hardness up to 3 × 1015 1 MeV neq/cm2 and time resolution below 2 ns, with uniform charge collection efficiency across the chip formed of 512 × 224 pixels with a size of 36.4 × 36.4 μm2. This is achieved when adopting high-resistivity Czochralski substrates with backside metallisation to obtain a good propagation of the bias voltage. This contribution will show the most recent results obtained on MALTA2 chip demonstrators, including signal efficiency, noise occupancy and time resolution, at different levels of irradiation as well as the performance of the MALTA telescope permanently installed at the SPS at CERN and used in the test beam campaign in 2021-2023.

Abstract:

The ATLAS trigger system is a crucial component of the ATLAS experiment at the LHC. It is responsible for selecting events in line with the ATLAS physics programme. This paper presents an overview of the changes to the trigger and data acquisition system during the second long shutdown of the LHC, and shows the performance of the trigger system and its components in the proton-proton collisions during the 2022 commissioning period as well as its expected performance in proton-proton and heavy-ion collisions for the remainder of the third LHC data-taking period (2022–2025).