Discriminating Z' signals in semileptonic top pair production at the LHC

We investigate the sensitivity of top pair production to the properties of different Beyond the Standard Model theories embedding a new neutral boson. We include six-fermion decay, and account for the full tree-level Standard Model ttbar interference, with all intermediate particles allowed off-shell. We focus on those observables best suited to the lepton-plus-jets final state at the LHC, and simulate the resulting experimental conditions, including kinematic requirements and top quark pair reconstruction in the presence of missing transverse energy and combinatorial ambiguity in quark-top assignment. In particular, we demonstrate the use of asymmetry observables to probe the coupling structure of a new neutral resonance, in addition to cases in which these asymmetries may even form complementary discovery observables in combination with the differential cross section.Comment: 4 pages, 1 figure, 1 table. arXiv admin note: substantial text overlap with arXiv:1610.0407

Using asymmetry observables to discover and distinguish Z' signals in top pair production with the lepton-plus-jets final state at the LHC

We study the sensitivity of top pair production with six-fermion decay at the LHC to the presence and nature of an underlying Z' boson, accounting for full tree-level Standard Model ttbar interference, with all intermediate particles allowed off-shell. We concentrate on the lepton-plus-jets final state and simulate experimental conditions, including kinematic requirements and top quark pair reconstruction in the presence of missing transverse energy and combinatorial ambiguity in jet-top assignment. We focus on the differential mass spectra of the cross section and asymmetry observables, especially demonstrating the use of the latter in probing the coupling structure of a new neutral resonance, in addition to cases in which the asymmetry forms a complementary discovery observable.Comment: 4 pages, proceedings contribution for Fourth Annual Large Hadron Collider Physics, 13-18 June 2016, Lund, Swede

Enabling discoverable trusted services for highly dynamic decentralized workflows

Fifth generation (5G) mobile networks will revolutionize edge-based computing by providing fast and reliable network capabilities to remote sensors, devices and microservices. This heralds new opportunities for researchers, allowing remote instrumentation and analytic capabilities to be as accessible as local resources. The increased availability of remote data and services presents new opportunities for collaboration, yet introduces challenges for workflow orchestration, which will need to adapt to consider an increased choice of available services, including those from trusted partners and the wider community. In this paper we outline a workflow approach that provides decentralized discovery and orchestration of verifiably trustable services in support of multi-party operations. We base this work on the adoption of standardised data models and protocols emerging from hypermedia research, which has demonstrated success in using combinations of Linked Data, Web of Things (WoT) and semantic technologies to provide mechanisms for autonomous goal-directed agents to discover, execute and reuse new heterogeneous resources and behaviours in large-scale, dynamic environments. We adopt Verifiable Credentials (VCs) to securely share information amongst peers based on prior service usage in a cryptographically secure and tamperproof way, providing a trust-based framework for ratifying service qualities. Collating these new service description channels and integrating with existing decentralized workflow research based on vector symbolic architecture (VSA) provides an enhanced semantic search space for efficient and trusted service discovery that will be necessary for 5G edge-computing environments

Effects of a multicomponent resistance-based exercise program with protein, vitamin D and calcium supplementation on cognition in men with prostate cancer treated with ADT: Secondary analysis of a 12-month randomised controlled trial

OBJECTIVES: The aim of this preplanned secondary analysis of a 12-month randomised controlled trial was to investigate the effects of a multicomponent exercise programme combined with daily whey protein, calcium and vitamin D supplementation on cognition in men with prostate cancer treated with androgen deprivation therapy (ADT). DESIGN: 12-month, two-arm, randomised controlled trial. SETTING: University clinical exercise centre. PARTICIPANTS: 70 ADT-treated men were randomised to exercise-training plus supplementation (Ex+ Suppl, n=34) or usual care (control, n=36). INTERVENTION: Men allocated to Ex + Suppl undertook thrice weekly resistance training with weight-bearing exercise training plus daily whey protein (25 g), calcium (1200 mg) and vitamin D (2000 IU) supplementation. PRIMARY AND SECONDARY OUTCOME MEASURES: Cognition was assessed at baseline, 6 and 12 months via a computerised battery (CogState), Trail-making test, Rey auditory-verbal learning test and Digit span. Data were analysed with linear mixed models and an intention-to-treat and prespecified per-protocol approach (exercise-training: ≥ 66%, nutritional supplement: ≥ 80%). RESULTS: Sixty (86%) men completed the trial (Ex + Suppl, n = 31; control, n = 29). Five (7.1%) men were classified as having mild cognitive impairment at baseline. Median (IQR) adherence to the exercise and supplement was 56% (37%-82%) and 91% (66%-97%), respectively. Ex + Suppl had no effect on cognition at any time. CONCLUSIONS: A 12-month multicomponent exercise training and supplementation intervention had no significant effect on cognition in men treated with ADT for prostate cancer compared with usual care. Exercise training adherence below recommended guidelines does not support cognitive health in men treated with ADT for prostate cancer. TRIAL REGISTRATION NUMBER: Australian and New Zealand Clinical Trial Registry (ACTRN12614000317695, registered 25/03/2014) and acknowledged under the Therapeutic Goods Administration Clinical Trial Notification Scheme (CT-2015-CTN-03372-1 v1)

Trustable service discovery for highly dynamic decentralized workflows

The quantity and capabilities of smart devices and sensors deployed as part of the Internet of Things (IoT) and accessible via remote microservices is set to rise dramatically as the provision of interactive data streaming increases. This introduces opportunities to rapidly construct new applications by interconnecting these microservices in different workflow configurations. The challenge is to discover the required microservices, including those from trusted partners and the wider community, whilst being able to operate robustly under diverse networking conditions. This paper outlines a workflow approach that provides decentralized discovery and orchestration of verifiably trustable services in support of multi-party operations. The approach is based on adoption of patterns from self-sovereign identity research, notably Verifiable Credentials, to share information amongst peers based on attestations of service descriptions and prior service usage in a privacy preserving and secure manner. This provides a dynamic, trust-based framework for ratifying and evaluating the qualities of different services. Collating these new service descriptions and integrating with existing decentralized workflow research based on vector symbolic architecture (VSA) provides an enhanced semantic search space for efficient and trusted service discovery that is necessary to support a diverse range of emerging edge-computing environments. An architecture for a dynamic decentralized service discovery system, is designed, and described through application to a scenario which uses trusted peers’ reported experiences of an anomaly detection service to determine service selection

Enabling discoverable trusted services for highly dynamic decentralized workflows

Fifth generation (5G) mobile networks will revolutionize edge-based computing by providing fast and reliable network capabilities to remote sensors, devices and microservices. This heralds new opportunities for researchers, allowing remote instrumentation and analytic capabilities to be as accessible as local resources. The increased availability of remote data and services presents new opportunities for collaboration, yet introduces challenges for workflow orchestration, which will need to adapt to consider an increased choice of available services, including those from trusted partners and the wider community. In this paper we outline a workflow approach that provides decentralized discovery and orchestration of verifiably trustable services in support of multi-party operations. We base this work on the adoption of standardised data models and protocols emerging from hypermedia research, which has demonstrated success in using combinations of Linked Data, Web of Things (WoT) and semantic technologies to provide mechanisms for autonomous goal-directed agents to discover, execute and reuse new heterogeneous resources and behaviours in large-scale, dynamic environments. We adopt Verifiable Credentials (VCs) to securely share information amongst peers based on prior service usage in a cryptographically secure and tamperproof way, providing a trust-based framework for ratifying service qualities. Collating these new service description channels and integrating with existing decentralized workflow research based on vector symbolic architecture (VSA) provides an enhanced semantic search space for efficient and trusted service discovery that will be necessary for 5G edge-computing environments

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

An Analysis of the Radiation Damage to the ATLAS Semiconductor Tracker End-Caps

The motivation, theoretical principles and analytical procedure for an assessment of the radiation damage to the ATLAS SCT end-caps is presented. An analysis of the leakage current across end-cap modules is performed for 2011 and 2012 data. A comparison between the observed and expected leakage current is made, with measurements favouring the shape of the theoretical evolution. Measured data is found to be systematically lower than predicted for a large subset of end-cap modules, while the remainder show surface current effects which interfere with bulk current observation. Uniform differences for modules at different radial distances suggest a radial temperature distribution in the end-caps, with absolute silicon sensor temperature to be established in further analysis

Phenomenology of searches for new neutral resonances in top quark pair production at the LHC

This report presents the research that I have done in conjunction with my supervisors Lucio Cerrito and Stefano Moretti, as well as in collaboration with Francesco Spanò, over the last three years of my studies. Chapter 6 presents work conducted as part of the e/ signature trigger group within the ATLAS collaboration. Chapter 7 presents work released in a publicly available paper, while the study discussed in chapter 8 I hope to be the subject of an upcoming publication. This thesis presents two studies considering new neutral resonances in top quark pair production at the Large Hadron Collider. Its focus is largely on charge and spin asymmetry observables sensitive to the chiral couplings of a Z′ boson. Both analyses employ a 2 ! 6 simulation accounting for all possible leading order topologies for both signal and (irreducible) top backgrounds including interference effects. The first is a parton-level analysis aimed at the lepton-plus-jets final state, using a reconstruction procedure of the (anti)top quark mass and momenta that closely mimics experimental conditions. Results show the potential of these observables to characterise the chiral couplings ofthe Z′ boson and distinguish between different theoretical models, and to improve the discovery potential in combination with the tt differential cross section. The second study extends to an analysis using the dilepton final state in top pair production to observe a new resonance, accounting for parton-shower, hadronisation and simulated reconstruction with the ATLAS detector. Several approaches to top reconstruction and their relative observational power are explored. Finally a study of the sources for single electron trigger inefficiencies with the ATLAS detector is presented