N=4 Supersymmetry on a Space-Time Lattice

Maximally supersymmetric Yang--Mills theory in four dimensions can be formulated on a space-time lattice while exactly preserving a single supersymmetry. Here we explore in detail this lattice theory, paying particular attention to its strongly coupled regime. Targeting a theory with gauge group SU(N), the lattice formulation is naturally described in terms of gauge group U(N). Although the U(1) degrees of freedom decouple in the continuum limit we show that these degrees of freedom lead to unwanted lattice artifacts at strong coupling. We demonstrate that these lattice artifacts can be removed, leaving behind a lattice formulation based on the SU(N) gauge group with the expected apparently conformal behavior at both weak and strong coupling

Quenched Chiral Artifacts for Wilson-Dirac Fermions

We examine artifacts associated with the chiral symmetry breaking induced through the use of Wilson-Dirac fermions in lattice Monte Carlo computations. For light quark masses, the conventional quenched theory can not be defined using direct Monte Carlo methods due to the existence of nonintegrable poles in physical quantities. These poles are associated with the real eigenvalue spectrum of the Wilson-Dirac operator. We show how this singularity structure can be observed in the analysis of both QED in two dimensions and QCD in four dimensions.Comment: 32 pages (Latex) including 13 figures (EPS

A Framework for Design Research in the Service Science Discipline

The emerging discipline of Service Science Management and Engineering (SSME) apart from developing theories strives to build and evaluate IT artifacts of utility for the service economy. Especially due to the interdisciplinary character of this new discipline and the imprint of rather behavioral science oriented disciplines, for some problem areas only few innovative artifacts have been scientifically published and evaluated. To counter this deficiency, we present a research framework for design research in the service science discipline. The framework is based on design (science) research literature and widely acknowledged service science perspectives. It addresses three dimensions: (1) four IT artifact types, (2) four perspectives on the service science, and (3) three levels of abstraction. Using the framework, gaps in the service science discipline yet to be addressed by IT artifacts can be identified. On the other hand, if abundant IT artifacts can be identified for any of the proposed research areas, artifacts might need to be systematized or combined

Investigating Software Engineering Artifacts in DevOps Through the Lens of Boundary Objects

Software engineering artifacts are central to DevOps, enabling the collaboration of teams involved with integrating the development and operations domains. However, collaboration around DevOps artifacts has yet to receive detailed research attention. We apply the sociological concept of Boundary Objects to describe and evaluate the specific software engineering artifacts that enable a cross-disciplinary understanding. Using this focus, we investigate how different DevOps stakeholders can collaborate efficiently using common artifacts. We performed a multiple case study and conducted twelve semi-structured interviews with DevOps practitioners in nine companies. We elicited participants\u27 collaboration practices, focusing on the coordination of stakeholders and the use of engineering artifacts as a means of translation. This paper presents a consolidated overview of four categories of DevOps Boundary Objects and eleven stakeholder groups relevant to DevOps. To help practitioners assess cross-disciplinary knowledge management strategies, we detail how DevOps Boundary Objects contribute to four areas of DevOps knowledge and propose derived dimensions to evaluate their use

MATrA: meta-modelling approach to traceability for avionics

PhD ThesisTraceability is the common term for mechanisms to record and navigate relationships between artifacts produced by development and assessment processes. Effective management of these relationships is critical to the success of projects involving the development of complex aerospace products. Practitioners use a range of notations to model aerospace products (often as part of a defined technique or methodology). Those appropriate to electrical and electronic systems (avionics) include Use Cases for requirements, Ada for development and Fault Trees for assessment (others such as PERT networks support product management). Most notations used within the industry have tool support, although a lack of well-defined approaches to integration leads to inconsistencies and limits traceability between their respective data sets (internal models). Conceptually, the artifacts produced using such notations populate four traceability dimensions. Of these, three record links between project artifacts (describing the same product), while the fourth relates artifacts across different projects (and hence products), and across product families within the same project. The scope of this thesis is to define a meta-framework that characterises traceability dimensions for aerospace projects, and then to propose a concrete framework capturing the syntax and semantics of notations used in developing avionics for such projects which enables traceability across the four dimensions. The concrete framework is achieved by exporting information from the internal models of tools supporting these notations to an integrated environment consisting of. i) a Workspace comprising a set of structures or meta-models (models describing models) expressed in a common modelling language representing selected notations (including appropriate extensions reflecting the application domain); ii) well-formedness constraints over these structures capturing properties of the notations (and again, reflecting the domain); and iii) associations between the structures. To maintain consistency and identify conflicts, elements of the structures are verified against a system model that defines common building blocks underlying the various notations. The approach is evaluated by (partial) tool implementation of the structures which are populated using case study material derived from actual commercial specifications and industry standards

Visualizing a Fourth Dimension: Hypercubic Resistor Networks

A booming field in physics research today is the search for extra dimensions. This is something that has been thought about and discussed in both the scientific and non-scientific world for a long time. Many physicists are currently attempting to answer the question: is our world really four dimensional? The purpose of this research, however, is not to answer that question. The purpose of this work is to help reveal four-dimensional artifacts in our perceived three-dimensional world in order to help a student, even a non-physicist, to understand and visualize how the extra spatial dimensionality, if present, might reveal itself in measurements. To that end, models of non-trivial four-dimensional objects have been constructed that have consequences large enough to be easily measured and understood in an intuitive fashion. In building and analyzing data from two, three, and four-dimensional model systems with non-trivial interactions, large and conceptually transparent consequences of extra spatial dimensions have been discovered

EU-Rent as an artifact-centric process model: technical report

Business process modeling using an artifact-centric approach has raised a significant interest over the last few years. This approach is usually stated in terms of the BALSA framework which defi nes the four dimensions of an artifact-centric business process model: Business Artifacts, Lifecycles, Services and Associations. One of the research challenges in this area is looking for diff erent diagrams to represent these dimensions. Bearing this in mind, this technical report shows how various UML diagrams can be used to represent all the elements in the BALSA framework by applying them to the EU-Rent case study.Preprin