Search for Dark Matter in events with missing transverse momentum and a Higgs boson decaying into bottom quarks with the ATLAS detector

Many astrophysical observations indicate the existence Dark Matter, which is not predicted by the Standard Model (SM) of particle physics. Many theories beyond the Standard Model (BSM) predict new heavy particles called WIMPs (Weakly Interacting Massive Particles). One way to search for WIMP dark matter is through its pair-production in collider experiments. A possible signature, in this case, is the associated production of a WIMP pair with a Higgs boson decaying to a pair of b-quarks. The WIMPs leave the detector without interacting, leading to events with a large amount of missing transverse momentum and two highly-energetic b-jets due to the decay of the Higgs boson. The search presented in this thesis uses such events based on data from proton-proton collisions recorded with the ATLAS detector from 2015 to 2018 at √s=13 TeV. A profile likelihood fit is performed to extract a possible signal. No significant excess above the SM predictions is observed, and the results are interpreted in terms of the Z'2HDM and 2HDM+a benchmark models. In addition, model-independent limits are set on the cross-section for new physics at 95% confidence level (CL). The thesis also presents a reinterpretation of the results in terms of the Dark-Higgs model. All physics analyses rely on the reconstruction of physics objects and the high-precision measurements of their energy and momentum. The outermost part of the ATLAS Inner Detector, Transition Radiation Tracker (TRT), contributes significantly to the momentum measurement of the charged particles by extending the length of the measured trajectories. This thesis describes studies of the drift-time calibration of the TRT. These studies examine the dependence of the calibration parameters on the transverse momentum of reconstructed tracks and pile-up using simulated events. Furthermore, the effect of additional drift-time corrections in straw tubes filled with Argon-based gas mixture is studied

Kinase Inhibitors in the Treatment of Ovarian Cancer: Current State and Future Promises

Ovarian cancer is the deadliest gynecological cancer, the high-grade serous ovarian carcinoma (HGSC) being its most common and most aggressive form. Despite the latest therapeutical advancements following the introduction of vascular endothelial growth factor receptor (VEGFR) targeting angiogenesis inhibitors and poly-ADP-ribose-polymerase (PARP) inhibitors to supplement the standard platinum- and taxane-based chemotherapy, the expected overall survival of HGSC patients has not improved significantly from the five-year rate of 42%. This calls for the development and testing of more efficient treatment options. Many oncogenic kinase-signaling pathways are dysregulated in HGSC. Since small-molecule kinase inhibitors have revolutionized the treatment of many solid cancers due to the generality of the increased activation of protein kinases in carcinomas, it is reasonable to evaluate their potential against HGSC. Here, we present the latest concluded and on-going clinical trials on kinase inhibitors in HGSC, as well as the recent work concerning ovarian cancer patient organoids and xenograft models. We discuss the potential of kinase inhibitors as personalized treatments, which would require comprehensive assessment of the biological mechanisms underlying tumor spread and chemoresistance in individual patients, and their connection to tumor genome and transcriptome to establish identifiable subgroups of patients who are most likely to benefit from a given therapy

Γενετικοί πολυμορφισμοί στη νόσο COVID 19

Γενετικοί επίκτητοι παράγοvτες κινδύνου σχετίζονται με τη λοίμωξη από Covid- 19. Σε αυτούς περιλαμβάνονται παράγοντες σχετικά με την επιρρέπεια προσβολής από τον ιό, την βαρύτητα της νόσου, την εξέλιξη σε αναπνευστική ανεπάρκεια και την παρακολούθηση ανταπόκρισης στην θεραπεία. Σε αυτό το πλαίσιο η μελέτη SAVE έδειξε στην πρώτη περίοδο της μελέτης την προστατευτική ικανότητα του της χορήγηση anakinra όσον αφορά την εξέλιξη σε σοβαρή αναπνευστική ανεπάρκεια (HR 0.28, 95% CI, 0,18-0,44,P<0.0001). Ακόμη, σημαντική διαφορά στο χρόνο εξέλιξης των ασθενών με λοίμωξη από Covid- 19 σε σοβαρή αναπνευστική ανεπάρκεια διαπιστώθηκε στην δεύτερη περίοδο της μελέτης στους ασθενείς που έλαβαν anakinra μαζί με Standard –of –care (SOC ) (HR 0.38, P< 0.0001). Τέλος, από την ανάλυση επιβίωσης διαπιστώθηκε βελτίωση της επιβίωσης ασθενών στις 30 ημέρες που έλαβαν anakinra μαζί με SOC σε σχέση με αυτούς που έλαβαν μόνο SOC θεραπεία ενώ η παλίνδρομη ανάλυση κατά Cox ανέδειξε παράγοντες κινδύνου που συνδέονται με αυξημένη θνητότητα και την εξέλιξη σε σοβαρή αναπνευστική ανεπάρκεια.The Covid -19 infection is associated with genetic polymorphisms. These include factors related to susceptibility to the virus, the severity of the disease, the development of respiratory failure, and monitoring response to treatment. In this context, the SAVE study showed in the first period of the study its protective ability of anakinra in the development of severe respiratory failure (HR 0.28, 95% CI, 0.18-0.44, P <0.0001). Also, a significant difference in the progression time of patients with Covid-19 infection to severe respiratory failure was found in the second period of the study in patients receiving anakinra with Standard-ofcare (SOC) (HR 0.38, P <0.0001). Finally, the survival analysis showed improved survival of patients in 30 days receiving anakinra with SOC compared with those receiving SOC treatment alone, while the Cox regression analysis revealed risk factors associated with increased mortality and progression to severe respiratory failure

Interactions of Trivalent Lanthanide Cations with a New Hexadentate Di-Schiff Base: New Lanthanide(III) Complexes from (NE,N′E)-2,2′-(ethane-1,2-diylbis(oxy))bis(N-(pyridin-2-ylmethylene)ethanamine)

The novel lanthanide(III) complexes [Ln(NO3)2L](NO3)·3MeOH (Ln = La 1, Pr 2) and [Ln(NO3)3L](NO3)·2MeOH (Ln = Gd 3, Yb 4), where L = (NE,N′E)-2,2′-(ethane-1,2-diylbis(oxy))bis(N-(pyridin-2-ylmethylene)ethanamine), have been obtained by direct reaction of the Schiff base ligand and the corresponding hydrated lanthanide(III) nitrates in methanol. All complexes were characterized spectroscopically and thermogravimetrically. Complex 4 was also characterized with crystallographic studies: orthorhombic P212121, a = 10.6683(14), b = 13.4752(15), c = 19.3320(26) Å. In the molecular structure of 4, Yb(III) is surrounded by all donor atoms of the Schiff base (four nitrogen and two oxygen atoms) and four oxygen atoms belonging to two bidentate chelating nitrato ligands

Possible relationship between Seismic Electric Signals (SES) lead time and earthquake stress drop

Stress drop values for fourteen large earthquakes with MW ≥ 5.4 which occurred in Greece during the period 1983–2007 are available. All these earthquakes were preceded by Seismic Electric Signals (SES). An attempt has been made to investigate possible correlation between their stress drop values and the corresponding SES lead times. For the stress drop, we considered the Brune stress drop, ΔσB, estimated from far field body wave displacement source spectra and ΔσSB derived from the strong motion acceleration response spectra. The results show a relation may exist between Brune stress drop, ΔσB, and lead time which implies that earthquakes with higher stress drop values are preceded by SES with shorter lead time

The ATLAS Trigger System for LHC Run 3 and Trigger performance in 2022

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)

A search for R-parity-violating supersymmetry in final states containing many jets in pp collisions at √s=13TeV with the ATLAS detector

A search for R-parity-violating supersymmetry in final states with high jet multiplicity is presented. The search uses 140fb−1 of proton-proton collision data at √s=13TeV collected by the ATLAS experiment during Run 2 of the Large Hadron Collider. The results are interpreted in the context of R-parity-violating supersymmetry models that feature prompt gluino-pair production decaying directly to three jets each or decaying to two jets and a neutralino which subsequently decays promptly to three jets. No significant excess over the Standard Model expectation is observed and exclusion limits at the 95% confidence level are extracted. Gluinos with masses up to 1800 GeV are excluded when decaying directly to three jets. In the cascade scenario, gluinos with masses up to 2340 GeV are excluded for a neutralino with mass up to 1250 GeV

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino