Factorization Properties of Soft Graviton Amplitudes

We apply recently developed path integral resummation methods to perturbative quantum gravity. In particular, we provide supporting evidence that eikonal graviton amplitudes factorize into hard and soft parts, and confirm a recent hypothesis that soft gravitons are modelled by vacuum expectation values of products of certain Wilson line operators, which differ for massless and massive particles. We also investigate terms which break this factorization, and find that they are subleading with respect to the eikonal amplitude. The results may help in understanding the connections between gravity and gauge theories in more detail, as well as in studying gravitational radiation beyond the eikonal approximation.Comment: 35 pages, 5 figure

Making sense of big data in health research: Towards an EU action plan.

Medicine and healthcare are undergoing profound changes. Whole-genome sequencing and high-resolution imaging technologies are key drivers of this rapid and crucial transformation. Technological innovation combined with automation and miniaturization has triggered an explosion in data production that will soon reach exabyte proportions. How are we going to deal with this exponential increase in data production? The potential of "big data" for improving health is enormous but, at the same time, we face a wide range of challenges to overcome urgently. Europe is very proud of its cultural diversity; however, exploitation of the data made available through advances in genomic medicine, imaging, and a wide range of mobile health applications or connected devices is hampered by numerous historical, technical, legal, and political barriers. European health systems and databases are diverse and fragmented. There is a lack of harmonization of data formats, processing, analysis, and data transfer, which leads to incompatibilities and lost opportunities. Legal frameworks for data sharing are evolving. Clinicians, researchers, and citizens need improved methods, tools, and training to generate, analyze, and query data effectively. Addressing these barriers will contribute to creating the European Single Market for health, which will improve health and healthcare for all Europeans

FERMION TO BOSON TRANSMUTATIONS IN 2+1 DIMENSIONS FROM A GENERAL PERSPECTIVE

Fermion to boson transmutation mechanisms in 2 + 1 dimensions are discussed within a broad and, at the same time, particularly simple theoretical setting

DISCRETIZATION IN THE CONTINUUM AND THE SPINORIAL FUNCTIONAL INTEGRAL

We introduce & discretization procedure for spinorial field theories which takes place within a continuous space-time background. The implications of our discretization scheme at the quantum level is that integration over fermionic degrees of freedom can be performed in & well-defined manner. The result is a regularized determinant which reproduces known properties of the continuum system. We consider both free and coupled, with a set of external gauge fields, models. We compute the trace of the logarithm of the Euclidean Dirac operator, obtained by our integration, in the representation provided by “position” eigenstates in Euclidean space-time. A two-dimensional application shows compliance of our result with both gauge current conservation and the axial anomaly relation. Finally, we discuss the question whether our discretization scheme provides a nonperturbative definition of spinorial field systems

Four-dimensional topological interpretation of the U(1) anomaly

We propose a stationary dyon-type configuration which gives rise to a topological charge density associated with the U(1) anomaly in four space-time dimensions

Theoretical evidence for a tachyonic ghost-state contribution to the gluon propagator in high-energy, forward quark-quark “Scattering”

Implications stemming from the inclusion of nonperturbative confining effects, as contained in the stochastic vacuum model of H. Dosch and Yu.A. Simonov, are considered in the context of a (hypothetical) quark-quark “scattering process” in the Regge kinematical region. In a computation wherein the nonperturbative input enters as a correction to established perturbative results, a careful treatment of infrared divergences is shown to imply the presence of an effective propagator associated with the existence of a linear term in the static potential. An equivalent statement is to say that the modified gluonic propagator receives a contribution from a tachyonic ghost state, an occurrence which is fully consistent with earlier suggestions made in the context of low-energy QCD phenomenology. (c) 2005 Pleiades Publishing, Inc

PARTICLE PATH-INTEGRAL APPROACH TO THE STUDY OF DIRAC SPIN-1/2 FIELD SYSTEMS

A novel approach to the study of fermionic systems in d-dimensional Euclidean spacetime is presented according to which an original, held-theoretical form of description is converted into a particle-based language. An important aspect of the advocated procedure is that it employs a spacetime resolution scale which does not have to serve, at the same time, as an,ultraviolet cutoff for matter field fluctuations. At the particle level of description, such fluctuations are independently regularized by a scale associated with a ‘’proper-time” parameter. A key feature of our representation for fermionic systems is its purely geometrical content. In particular, Polyakov’s spin factor, which enters the path integral description of spin-1/2 entities, emerges very naturally in the course of passing from the field-theoretical to the particle-based language. The applications considered in this paper pertain to evaluations of the Dirac determinant. In the presence of a coupling to ran external gauge field, such computations lead to effective-action terms. Both Maxwell and topological terms are retrieved in two, three,and four spacetime dimensions