Grand unified theories in extra dimensions

The Standard Model (SM) of Particle Physics is currently our best understanding of the laws of nature. At the same time it cannot account for a variety of phenomena, and has a series of shortcomings regarding its own structure. Beyond the Standard Model physics aims to address these issues, where Grand Unified Theories (GUTs) provide a solution to some of questions regarding the structure, which in turn address some of the phenomenological problems present in the SM. In the following thesis we explore the phenomenology of GUTs, along with their valid parameter spaces and experimental signatures. This is done within an extra dimensional scenario, where we look at 5D and 6D models, within flat and warped contexts. In this work we have ruled out a series of models and explored the use of unification metrics to guide model building via renormalisation group equation analysis within different regimes. To achieve this we have employed a variety of numerical and evolutionary algorithms

Scherk-Schwarz orbifolds at the LHC

We examine orbifold theories of Grand Unification with Scherk-Schwarz twisting, performing a renormalisation group analysis and applying low energy experimental constraints. We rule out the minimal SU(5) models, and consider simple extensions including additional fields, such as an additional scalar field, or additional symmetries, such as $SU(5)\times U(1)$ or $E_6$. We find that it is very difficult to generate a large enough Higgs mass while simultaneously passing LHC experimental search constraints.Comment: 26 pages, 12 figures; v3: Version accepted for publication; v4: Typos correcte

Confronting Scherk-Schwartz orbifold models with LHC data

In the following proceedings we will outline our recent efforts aimed at analysing a class of models known as orbifold GUTs and their phenomenology in a variety of minimal and non-minimal settings. We examine the minimal SU(5) models, rule them out, and proceed by extending them with an additional scalar field along with a gauge extension via SU(5)×U(1) models. We end up by commenting on the future improvements needed to more accurately handle exclusions along with tracing the U(1) gauge extensions to more complete 6D theories

Confronting Scherk-Schwartz orbifold models with LHC data

In the following proceedings we will outline our recent efforts aimed at analysing a class of models known as orbifold GUTs and their phenomenology in a variety of minimal and non-minimal settings. We examine the minimal SU(5) models, rule them out, and proceed by extending them with an additional scalar field along with a gauge extension via SU(5)×U(1) models. We end up by commenting on the future improvements needed to more accurately handle exclusions along with tracing the U(1) gauge extensions to more complete 6D theories

Phenomenology of GUT-inspired gauge-Higgs unification

We perform a detailed investigation of a Grand Unified Theory (GUT)-inspired theory of gauge-Higgs unification. Scanning the model's parameter space with adapted numerical techniques, we contrast the scenario's low energy limit with existing SM and collider search constraints. We discuss potential modifications of di-Higgs phenomenology at hadron colliders as sensitive probes of the gauge-like character of the Higgs self-interactions and find that for phenomenologically viable parameter choices modifications of the order of 20\% compared to the SM cross section can be expected. While these modifications are challenging to observe at the LHC, a future 100 TeV hadron collider might be able to constrain the scenario through more precise di-Higgs measurements. We point out alternative signatures that can be employed to constrain this model in the near future.Comment: 10 pages, 9 figures, 1 table; v2: references added, version published in PL

The Weinberg Angle and 5D RGE effects in a SO(11) GUT theory

The Weinberg angle is an important parameter in Grand Unified Theories (GUT) as its size is crucially influenced by the assumption of unification. In scenarios with different steps of symmetry breaking, in particular in models that involve gauge-Higgs unification, the connection of the ultraviolet theory and the TeV scale-relevant, effective Standard Model description is an important test of the models' validity. In this work, we consider a 6D gauge-Higgs unification GUT scenario and explore the TeV scale-GUT relation using a detailed RGE analysis in the 4D and 5D regimes of the theory, including constraints from LHC measurements. We show that such can be consistent with unification in the light of current constraints, while the Weinberg angle likely translates into concrete conditions on the fermion sector in the higher dimensional setup.Comment: 14 pages, 9 figures, 5 tables; v2 Version accepted for publication, updated figures and result

Characterization and performance studies of high-voltage CMOS based pixel sensors

The high luminosity upgrade of the LHC will push the limits for detectors, specially the silicon trackers which are closest to the interaction point. The ATLAS CMOS Sensor R&D efort is investigating a new technology using high-voltage CMOS processes for producing pixel and strip sensors. In contrast to the currently used technology these devices implement active electronics on the sensor itself, offering a multitude of tuning parameters for achieving the best performance. My summer project revolved around characterising existing samples along with assembling and debugging hardware required for their improvement and functionality. Other tasks involved writing communication protocols using pyBAR to remotely control injection circuitry on a GPAC card, and helping various members of the group with data collection and analysis. Through the summer student programme I have had the opportunity to be part of a vibrant scientic community at the forefront of research, to create bonds with fellow students from universities across the world and to further my understanding in particle physics

Diagnosis and Management of Febrile Neutropenia in Pediatric Oncology Patients—A Systematic Review

Infectious diseases are associated with a high morbidity and mortality rate among pediatric cancer patients undergoing treatment or receiving a transplant. Neutropenia represents a potentially fatal complication of cancer treatment and is associated with a high risk of developing bacterial infections. Although febrile neutropenia (FN) can affect both adults and children, the latter has a higher chance of infections with an unknown origin. Prompt empiric broad-spectrum antibiotic administration is collectively considered the best therapeutic approach. This review aims to analyze the latest works from the literature regarding the therapeutic strategies, schemes, and approaches and the efficacy of these in pediatric febrile neutropenia. Following PRISMA guidelines, an advanced search on PubMed, Scopus, and Cochrane Library, using the keywords “febrile neutropenia”, “pediatric”, “cancer”, and “oncology”, was performed. A total of 197 articles were found to be eligible. After screening the abstracts and excluding unfit studies, 16 articles were analyzed. There were eight retrospective studies, five prospective studies, and two clinical trials. Altogether, these studies have described around 5000 episodes of FN. The median age of the participants was 7.6 years, and the underlying condition for most of them was acute leukemia. The infectious agent could only be determined in around one-fifth of cases, from which 90% were of bacterial origin. As such, empirical broad-spectrum antibiotics are used, with the most used treatment scheme comprising third- and fourth-generation cephalosporins and antipseudomonal penicillins. In order to improve the treatment strategies of FN episodes and to successfully de-escalate treatments toward narrower-spectrum antibiotics, hospitals and clinics should increase their efforts in identifying the underlying cause of FN episodes through blood culture urine culture and viral tests, wherever infrastructure enables it

Prognosis Communication in Pediatric Oncology: A Systematic Review

Background: While communication plays an important role in medicine, it also often represents a challenge when the topic at hand is the prognosis of a high-risk condition. When it comes to pediatric oncology, the challenge becomes even greater for physicians who have to adapt their discourse to both the child and their family. Methods: Following the PRISMA guidelines, an advanced search on PubMed, Scopus and the Cochrane Library was performed, from 1 January 2017 to 31 October 2022. Demographic data for caregivers, pediatric patients and physicians were extracted, as well as diagnosis, prognosis, presence at discussion, emotional states and impact on life, trust, decision roles, communication quality and other outcomes. Results: A total of 21 articles were analyzed. Most studies (17) focused on caregivers, while only seven and five studies were focused on children and physicians, respectively. Most parents reported high trust in their physicians (73.01%), taking the leading role in decision making (48%), moderate distress levels (46.68%), a strong desire for more information (78.64%), receiving high-quality information (56.71%) and communication (52.73%). Most children were not present at discussions (63.98%); however, their desire to know more was expressed in three studies. Moreover, only two studies observed children being involved in decision making. Most physicians had less than 20 years of experience (55.02%) and reported the use of both words and statistics (47.3%) as a communication method. Conclusions: Communication research is focused more on caregivers, yet children may understand more than they seem capable of and want to be included in the conversation. More studies should focus on and quantify the opinions of children and their physicians. In order to improve the quality of communication, healthcare workers should receive professional training