1,514 research outputs found

    Novel approaches to the study of the heavy meson spectrum at finite temperature

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    This thesis is structured in three broad sections. The first presents a brief intro-duction to the field of quantum chromodynamics (QCD) and regularisation methods, which precedes a more thorough description of the lattice field theoretic approach to QCD and its non-relativistic formalism, NRQCD, which is used in the analysis contained within this document. The second section introduces the first problem of interest, spectral reconstruction in the case of bottomonium mesons. We focus in particular on the Laplacian nature of the problem and present the Backus-Gilbert method as a means of pro-ducing regularised solutions. The resolving power of the method is discussed and the overall approach is then extended with the inclusion of a novel technique known as Laplace shifting, which takes advantage of the structure of the problem to pro-vide a controlled resolution improvement to the method. A study of this technique is presented and applied to results obtained from Fastsum’s anisotropic NRQCD ensembles from which connections with a known phenomenon in Monte-Carlo based physics called Parisi-Lepage statistical scaling are elucidated. The third and final section focuses on probing the temperature dependence of the gluon propagator again calculated using the Fastsum Gen-2L ensembles. We begin by showing results for the propagator in the Coulomb gauge, before extending to the Landau gauge where we discuss the necessary modifications to support the lattice anisotropy

    Advisor and Student Experiences of Summer Support for College-intending, Low-income high school graduates

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    Summer melt occurs when students who have been accepted to college and intend to enroll fail to matriculate in college in the fall semester after high school. A high rate of summer melt contributes to the lower postsecondary attainment rates of low-income students, in particular. This article presents qualitative findings from two interventions intended to reduce summer melt among low-income, urban high school graduates who had been accepted to college and indicated their intention to enroll. Results from student and counselor surveys, interviews, and focus groups point to a web of personal and contextual factors that collectively influence students' college preparation behaviors and provide insight into the areas of summer supports from which students like these can benefit. The data fit an ecological perspective, in which personal, institutional, societal, and temporal factors interact to affect students' behaviors and outcomes. A model of summer intervention shows that obstacles in completing college financing and informational tasks can lead college-intending students to re-open the question of where or whether to attend college in the fall after high school graduation. Given the pressure of concerns about how to actualize their offer of admission, students rarely engage in the anticipatory socialization activities that might help them make optimal transitions into college

    The Segment Ontology: Bridging Music-generic and Domain-specific

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    Existing semantic representations of music analysis encapsulate narrow sub-domain concepts and are frequently scoped by the context of a particular MIR task. Segmentation is a crucial abstraction in the investigation of phenomena which unfold over time; we present a Segment Ontology as the backbone of an approach that models properties from the musicological domain independently from MIR implementations and their signal processing foundations, whilst maintaining an accurate and complete description of the relationships that link them. This framework provides two principal advantages which are explored through several examples: a layered separation of concerns that aligns the model with the needs of the users and systems that consume and produce the data; and the ability to link multiple analyses of differing types through transforms to and from the Segment axis

    More than Dollars for Scholars: The Impact of the Dell Scholars Program on College Access, Persistence and Degree Attainment

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    Although college enrollment rates have increased substantially over the last several decades, socioeconomic inequalities in college completion have actually widened over time. A critical question, therefore, is how to support low-income and first-generation students to succeed in college after they matriculate. We investigate the impact of the Dell Scholars Program which provides a combination of generous financial support and individualized advising to scholarship recipients before and throughout their postsecondary enrollment. The program's design is motivated by a theory of action that, in order to meaningfully increase the share of lower-income students who earn a college degree, it is necessary both to address financial constraints students face and to provide ongoing support for the academic, cultural and other challenges that students experience during their college careers. We isolate the unique impact of the program on college completion by capitalizing on an arbitrary cutoff in the program's algorithmic selection process. Using a regression discontinuity design, we find that although being named a Dell Scholar has no impact on initial college enrollment or early college persistence, scholars at the margin of eligibility are significantly more likely to earn a bachelor's degree on-time or six years after high school graduation. These impacts are sizeable and represent a nearly 25 percent or greater increase in both four- and six-year bachelor's attainment. The program is resource intensive. Yet, back-of-theenvelope calculations indicate that the Dell Scholars Program has a positive rate of return

    Applications of a Neo-Aristotelian metaphysics of powers in the domain of Philosophy of Religion

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    This thesis explores some applications of a Neo-Aristotelian metaphysics to philosophy of religion, with a particular focus on the metaphysics of powers. This widens the uses of such an ontology within the contemporary literature, since power metaphysics has been much neglected in philosophy of religion. The thesis starts by introducing power ontology and many of the questions that have been explored within it, noting when these will be relevant for what is to come later in the thesis. It then turns to exploring ways in which, I claim, a power ontology can be used within philosophy of religion. The first thing I explore is the Trinity, where I claim that powers are able to provide a metaphysics for this. The following chapter explores how God might create laws of nature and why I think the powers position should be preferred. I then explore how powers might provide the foundation to object to the fine- tuning argument, and after formulating this response explore how successful it is. In the penultimate chapter I examine how powers might inspire us with a solution to the Euthyphro dilemma against theistic meta-ethics, and formulate a position based on this. In the final chapter I then try to show how what I have said in the previous chapter can be thought of in terms of powers alone, such that powers have a role to play within axiology

    Generational accounts for the United States: an update

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    An examination of the continuing generational imbalance in U.S. fiscal policy, showing that under current policy, future generations will have to pay almost half of their lifetime labor incomes in net taxes to balance the government's book--more than 70% greater than the 28.6% today's newborns are slated to give up.Fiscal policy ; Taxation

    The supersingular Endomorphism Ring and One Endomorphism problems are equivalent

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    The supersingular Endomorphism Ring problem is the following: given a supersingular elliptic curve, compute all of its endomorphisms. The presumed hardness of this problem is foundational for isogeny-based cryptography. The One Endomorphism problem only asks to find a single non-scalar endomorphism. We prove that these two problems are equivalent, under probabilistic polynomial time reductions. We prove a number of consequences. First, assuming the hardness of the endomorphism ring problem, the Charles--Goren--Lauter hash function is collision resistant, and the SQIsign identification protocol is sound. Second, the endomorphism ring problem is equivalent to the problem of computing arbitrary isogenies between supersingular elliptic curves, a result previously known only for isogenies of smooth degree. Third, there exists an unconditional probabilistic algorithm to solve the endomorphism ring problem in time O~(sqrt(p)), a result that previously required to assume the generalized Riemann hypothesis. To prove our main result, we introduce a flexible framework for the study of isogeny graphs with additional information. We prove a general and easy-to-use rapid mixing theorem

    NNLO final-state quark-pair corrections in four dimensions

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    R.P. acknowledges the financial support of the MINECO Project FPA2016-78220-C3-3-P and the hospitality of the CERN TH department during the completion of this work. Our figures are prepared with Axodraw.We describe how NNLO final state quark-pair corrections are computed in FDR by directly enforcing gauge invariance and unitarity in the definition of the regularized divergent integrals. We give details of our approach and show how virtual and real contributions can be merged together without relying, explicitly or implicitly, on dimensional regularization. As an example, we recompute the H→bb¯+jets and γ∗→jets inclusive rates at the NNLO accuracy in the large NF limit of QCD. This demonstrates, for the first time, that physical results with intermediate infrared singularities can be obtained at NNLO using a fully four-dimensional procedure.Financial support of the MINECO Project FPA2016-78220-C3-3-
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