Improved Epstein-Glaser Renormalization II. Lorentz invariant framework

The Epstein--Glaser type T-subtraction introduced by one of the authors in a previous paper is extended to the Lorentz invariant framework. The advantage of using our subtraction instead of Epstein and Glaser's standard W-subtraction method is especially important when working in Minkowski space, as then the counterterms necessary to keep Lorentz invariance are simplified. We show how T-renormalization of primitive diagrams in the Lorentz invariant framework directly relates to causal Riesz distributions. A covariant subtraction rule in momentum space is found, sharply improving upon the BPHZL method for massless theories.Comment: LaTeX, 15 pages, no figure. Version to be published in J. Math. Phys. (Section 7 on the Massive Case and some references have been withdrawn). To the Memory of Laurent Schwart

Synthetic synchrotron emission maps from MHD models for the jet of M87

We present self-consistent global, steady-state MHD models and synthetic optically thin synchrotron emission maps for the jet of M87. The model consist of two distinct zones: an inner relativistic outflow, which we identify with the observed jet, and an outer cold disk-wind. While the former does not self-collimate efficiently due to its high effective inertia, the latter fulfills all the conditions for efficient collimation by the magneto-centrifugal mechanism. Given the right balance between the effective inertia of the inner flow and the collimation efficiency of the outer disk wind, the relativistic flow is magnetically confined into a well collimated beam and matches the measurements of the opening angle of M87 over several orders of magnitude in spatial extent. The synthetic synchrotron maps reproduce the morphological structure of the jet of M87, i.e. center-bright profiles near the core and limb-bright profiles away from the core. At the same time, they also show a local increase of brightness at some distance along the axis associated to a recollimation shock in the MHD model. Its location coincides with the position of the optical knot HST-1. In addition our best fitting model is consistent with a number of observational constraints such as the magnetic field in the knot HST-1, and the jet-to-counterjet brightness ratio.Comment: 9 pages, 9 figures, accepted by Ap

A new antisymmetric bilinear map for type-I gauge theories

In the case of gauge theories, which are ruled by an infinite-dimensional invariance group, various choices of antisymmetric bilinear maps on field functionals are indeed available. This paper proves first that, within this broad framework, the Peierls map (not yet the bracket) is a member of a larger family. At that stage, restriction to gauge-invariant functionals of the fields, with the associated Ward identities and geometric structure of the space of histories, make it possible to prove that the new map is indeed a Poisson bracket in the simple but relevant case of Maxwell theory. The building blocks are available for gauge theories only: vector fields that leave the action functional invariant; the invertible gauge-field operator, and the Green function of the ghost operator.Comment: 10 page

La minería y la industria del estaño

[Resumen] En este artículo se hace un breve repaso de la historia del estaño y su utilización por el hombre, desde los comienzos de la civilización hasta el presente. En él se enumeran los usos más relevantes del mismo y se sitúan, con la precisión histórica que es posible en cada caso, los momentos más florecientes de su industria y los hechos que condicionan su presente y muy probablemente su futuro.[Abstract] This article presents a short revision of the history of tin and its use by men from the beginnings of civilization to this day. The rrost important uses of tin are ennumerated in the paper, and the most flowishing moments of its industry, as well as the facts that determine its present and likely its future are stated with as much historic preciseness as possible

From Peierls brackets to a generalized Moyal bracket for type-I gauge theories

In the space-of-histories approach to gauge fields and their quantization, the Maxwell, Yang--Mills and gravitational field are well known to share the property of being type-I theories, i.e. Lie brackets of the vector fields which leave the action functional invariant are linear combinations of such vector fields, with coefficients of linear combination given by structure constants. The corresponding gauge-field operator in the functional integral for the in-out amplitude is an invertible second-order differential operator. For such an operator, we consider advanced and retarded Green functions giving rise to a Peierls bracket among group-invariant functionals. Our Peierls bracket is a Poisson bracket on the space of all group-invariant functionals in two cases only: either the gauge-fixing is arbitrary but the gauge fields lie on the dynamical sub-space; or the gauge-fixing is a linear functional of gauge fields, which are generic points of the space of histories. In both cases, the resulting Peierls bracket is proved to be gauge-invariant by exploiting the manifestly covariant formalism. Moreover, on quantization, a gauge-invariant Moyal bracket is defined that reduces to i hbar times the Peierls bracket to lowest order in hbar.Comment: 14 pages, Late

Local covariant quantum field theory over spectral geometries

A framework which combines ideas from Connes' noncommutative geometry, or spectral geometry, with recent ideas on generally covariant quantum field theory, is proposed in the present work. A certain type of spectral geometries modelling (possibly noncommutative) globally hyperbolic spacetimes is introduced in terms of so-called globally hyperbolic spectral triples. The concept is further generalized to a category of globally hyperbolic spectral geometries whose morphisms describe the generalization of isometric embeddings. Then a local generally covariant quantum field theory is introduced as a covariant functor between such a category of globally hyperbolic spectral geometries and the category of involutive algebras (or *-algebras). Thus, a local covariant quantum field theory over spectral geometries assigns quantum fields not just to a single noncommutative geometry (or noncommutative spacetime), but simultaneously to ``all'' spectral geometries, while respecting the covariance principle demanding that quantum field theories over isomorphic spectral geometries should also be isomorphic. It is suggested that in a quantum theory of gravity a particular class of globally hyperbolic spectral geometries is selected through a dynamical coupling of geometry and matter compatible with the covariance principle.Comment: 21 pages, 2 figure

Analysis of the Commercial Bank Performance in Indonesia and China

The purpose of this study is to compare the impact of capital structure on commercial banks' performance in Indonesia and China. The study chose 13 commercial banks from Indonesia and 12 banks from China for the period of 5 years, from 2015 to 2019. The study deployed a data panel regression analysis to analyze the secondary data that was obtained from the financial statements of these commercial banks. In this study, ROA and ROE are the measures used for Bank Performance. Four dependent variables: loan to deposit ratio, debt to asset ratio, capital adequacy and asset size are the independent variables. The results showed that LTD, AS and DTA have positive significant influences on ROA, while DTA and CAR have positive significant relationship on ROE in the study of Indonesian banks. Only AS have negative significant impact on both ROA and ROE, DTA and CAR have positive significant impact on ROA, while LTD has significant relationship on ROE in the study of commercial banks in China

Personal Attitude, Subjective Norm, and Perceived Behavioral Control: Differentiating Factors of Entrepreneurial Intention of High School Students who are Joining and not Joining the Entrepreneurship Education in an International School

The Indonesian government provides an incentive to develop entrepreneurship to boost economic growth and to prepare for the ASEAN Economic Community (AEC) by increasing the entrepreneurial intentions of the Indonesian people. One way to develop entrepreneurial intentions is to apply entrepreneurship education early on. The Singapore National Academy (SNA) is an international school that offers the Business subject from grades 9 - 12. SNA also offers another form of entrepreneurship education, which is the Enterprising co-curricular activity (CCA) that is more focused on projectbased learning. This study was conducted in SNA, which has students of various ethnic groups who mostly have parents with an entrepreneurial background. The purpose of this study was to elucidate whether personal attitude (PA), subjective norm (SN), and perceived behavioral control (PBC) affect the intention of entrepreneurship of students who are joining CCA Enterprising and students who are not joining CCA Enterprising in SNA. The sample consisted of 60 respondents, including 30 students of CCA Enterprising and 30 students who were not in CCA Enterprising, who were recruited using a saturated sampling technique. Based on the results of the discriminant analysis with the stepwise method, all variables (subjective norm, personal attitude and perceived behavioral control) affected the entrepreneurial intention of students who were joining CCA Enterprising compared with students who were not joining CCA Enterprising. There was a significant difference between the entrepreneurship intentions of those in CCA Enterprising compared with those who were not. Keywords: entrepreneurship education, personal attitude, subjective norm, perceived behavioural control, entrepreneurial intentio