Search for Supersymmetry in Final States with 2 or 3 Leptons with Data collected by the ATLAS Experiment

In this thesis I have presented a search for supersymmetry using data gathered by the ATLAS Detector from the Large Hadron Collider during the data-taking period from 2015 to 2016. In particular, this search looks for chargino and neutralino particles and targets several areas of phase space that haven’t been excluded yet. These particles are searched for in two different final states (the 2-lepton, 2-jet + E(miss)(T) final state and the 3-lepton + E(miss)(T) final state). This analysis also uses a novel method of variable construction called the “Recursive Jigsaw Reconstruction” method. This method has the potential to increase the sensitivity of analyses to signatures of SUSY particles without the need to dramatically increase the amount of data analysed.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 202

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Some aspects of misdemeanors pursuant to the prevention of riots at sport competitions act

U zadnje vrijeme svjedoci smo učestalih protupravnih ponašanja na športskim natjecanjima u Republici Hrvatskoj. Upravo stoga, o ovoj temi se sve više javno raspravlja, a rezultat toga je i donošenje Zakona o sprječavanju nereda na športskim natjecanjima. Iako je taj Zakon, koji je donesen 2003. godine, bio od velikog značaja glede uređenja jedne ovako važne problematike, ubrzo se pristupilo njegovoj izmjeni i dopuni budući da nisu bila riješena neka važna pitanja. Prva izmjena i dopuna tog Zakona bila je 2006. godine, a druga 2009. godine. Svaka izmjena i dopuna Zakona doprinijela je boljem uređenju koje se odnosi na sprječavanje, suzbijanje i sankcioniranje protupravnih ponašanja, ali su, prema mišljenju autora, i dalje ostala pojedina neriješena pitanja, o čemu će biti govora u ovom radu.Recently, we have borne witness to more frequent unlawful behavior at sport competitions in the Republic of Croatia. It is precisely because of this that the topic is being publicly discussed more often and has resulted in the Prevention of Riots at Sport Competitions Act. Even though this law, passed in 2003, was of great significance in regulating this very important problem area, its amendments were approached quickly given that some important issues had not yet been addressed. The first amendment to that Act was in 2006 and the other in 2009. Every amendment contributed to better regulation of preventing, combating and sanctioning unlawful behavior. However, in the authors’ opinion, there are other issues still left unresolved and these will be discussed in this paper

Neki aspekti prekršaja prema Zakonu o sprječavanju nereda na športskim natjecanjima

U zadnje vrijeme svjedoci smo učestalih protupravnih ponašanja na športskim natjecanjima u Republici Hrvatskoj. Upravo stoga, o ovoj temi se sve više javno raspravlja, a rezultat toga je i donošenje Zakona o sprječavanju nereda na športskim natjecanjima. Iako je taj Zakon, koji je donesen 2003. godine, bio od velikog značaja glede uređenja jedne ovako važne problematike, ubrzo se pristupilo njegovoj izmjeni i dopuni budući da nisu bila riješena neka važna pitanja. Prva izmjena i dopuna tog Zakona bila je 2006. godine, a druga 2009. godine. Svaka izmjena i dopuna Zakona doprinijela je boljem uređenju koje se odnosi na sprječavanje, suzbijanje i sankcioniranje protupravnih ponašanja, ali su, prema mišljenju autora, i dalje ostala pojedina neriješena pitanja, o čemu će biti govora u ovom radu

The Relationship between Nrf2 and HO-1 with the Severity of COVID-19 Disease

Nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) have significant roles in the development of a hyperinflammatory state in infectious diseases. We aimed to investigate the association of the serum concentrations of Nrf2 and HO-1 with the severity of COVID-19 disease. The study included 40 subjects with mild and moderately severe forms of the disease (MEWS scoring system ≤2). Twenty of the subjects had MEWS scores of 3 or 4, which indicate a severe form of the disease, and twenty subjects had a MEWS score of ≥5, which indicates a critical form of the disease. HO-1 and Nrf2 were measured using the commercially available Enzyme-Linked Immunosorbent Assay (ELISA). Subjects with the most severe form of COVID-19 (critically ill) had a lower concentration of Nrf2 that negatively correlated with the markers of hyperinflammatory response (CRP, IL-6, ferritin). This observation was not made for HO-1, and the correlation between Nrf2 and HO-1 values was not established. In the mild/moderate form of COVID-19 disease, Nrf2 was associated with an increased 1,25 dihydroxy vitamin D concentration. The results of this study show that Nrf2 has a role in the body’s anti-inflammatory response to COVID-19 disease, which makes it a potential therapeutic target

The Relationship between Nrf2 and HO-1 with the Severity of COVID-19 Disease

Nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) have significant roles in the development of a hyperinflammatory state in infectious diseases. We aimed to investigate the association of the serum concentrations of Nrf2 and HO-1 with the severity of COVID-19 disease. The study included 40 subjects with mild and moderately severe forms of the disease (MEWS scoring system ≤2). Twenty of the subjects had MEWS scores of 3 or 4, which indicate a severe form of the disease, and twenty subjects had a MEWS score of ≥5, which indicates a critical form of the disease. HO-1 and Nrf2 were measured using the commercially available Enzyme-Linked Immunosorbent Assay (ELISA). Subjects with the most severe form of COVID-19 (critically ill) had a lower concentration of Nrf2 that negatively correlated with the markers of hyperinflammatory response (CRP, IL-6, ferritin). This observation was not made for HO-1, and the correlation between Nrf2 and HO-1 values was not established. In the mild/moderate form of COVID-19 disease, Nrf2 was associated with an increased 1,25 dihydroxy vitamin D concentration. The results of this study show that Nrf2 has a role in the body’s anti-inflammatory response to COVID-19 disease, which makes it a potential therapeutic target

Defect level identification of ATLAS ITk Strip Sensors using DLTS

As a part of ongoing studies in parallel to ITk Strip Sensor Production quality control (QC) and quality assurance (QA), diodes fabricated as test structures were measured using \emph{Deep-Level Transient Spectroscopy} (DLTS). This was done to achieve precise sensor simulations motivated by findings of anomalous leakage current behaviour, as well as to compile a more complete model of radiation damage in ITk Strip Sensors. Utilising DLTS spectra with varying test parameters, trap energy levels and cross-sections associated with defects in the devices were obtained. Furthermore, employing related measurements techniques, such as Thermal Admittance Spectroscopy (TAS), results were supplemented and expanded, or additional points of interest, such as the deep level profile and the capture kinematics of the trap levels, were investigated with double-pulse DLTS (DDLTS). A common trap consistent with a $\mathrm{C_i O_i}$ point defect in unirradiated diodes was identified, but also an additional trap suspected to cause high leakage current. In proton-irradiated diodes, defects related to vacancy clusters or a boron-hydrogen complex were observed

Identification and Recovery of ATLAS18 Strip Sensors with High Surface Static Charge

The new all-silicon Inner Tracker (ITk) is being constructed by the ATLAS collaboration to track charged particles produced at the High-Luminosity LHC. The outer portion of the ITk detector will include nearly 18,000 highly segmented and radiation hard silicon strip sensors (ATLAS18 design). Throughout the production of 22,000 sensors, the strip sensors are subjected to a comprehensive suite of mechanical and electrical tests as part of the Quality Control (QC) program. In a large fraction of the batches delivered to date, high surface electrostatic charge has been measured on both the sensors and the plastic sheets which sheathe the sensors for shipping and handling rigidity. Aggregate data from across QC sites indicate a correlation between observed electrical failures and the sensor/plastic sheet charge build up. To mitigate these issues, the QC testing sites introduced recovery techniques involving UV light or flows of ionizing gas. Significant modifications to sensor handling procedures were made to prevent subsequent build up of static charge. This publication details a precise description of the issue, a variety of sensor recovery techniques, and trend analyses of sensors initially failing electrical tests (IV, strip scan, etc.)