Исследование парного рождения векторных бозонов с последующим распадом на заряженные лептоны и адроны в эксперименте ATLAS

This PhD thesis is dedicated to several studies in the search for new physics in the production of electroweak vector boson pairs. The work reports a search for heavy resonances decaying into a ZZ or ZW pair with data, corresponding to an integrated luminosity of 139 $\text{fb}^{-1}$, collected by the ATLAS detector in 2015-2018. The search is performed in the final states in which one Z boson decays to a pair of charged leptons (electrons or muons) and the associated Z or W boson decays hadronically. No evidence for the production of new resonances was observed. Therefore, upper bounds are placed on the possible resonance masses in a Heavy Vector Triplet model and on Bulk Randall-Sundrum Gravitons. Some models predict the non-resonant manifestation of new physics through a change in the cross-section of the vector boson scattering (VBS) process predicted in the electroweak sector of the Standard Model. This thesis presents the results of the first measurement of VBS in semileptonic channels using 35.5 $\text{fb}^{-1}$ of proton-proton collision data recorded in 2015 and 2016. The fiducial cross-section was extracted and is consistent with the Standard Model prediction. Finally, the thesis presents the result of the ATLAS Level-1 Tile Muon trigger upgrade performed in 2014-2015 to provide suppression of fake muon triggers that appeared due to slow charged particles in the forward kinematic regions of the ATLAS detector. The system has been running successfully since 2015.