On the construction of a finite Siegel space

In this note we construct a finite analogue of classical Siegel's Space. Our approach is to look at it as a non commutative Poincare's half plane. The finite Siegel Space is described as the space of Lagrangians of a $2n$ dimensional space over a quadratic extension $E$ of a finite base field $F$. The orbits of the action of the symplectic group $Sp(n,F)$ on Lagrangians are described as homogeneous spaces. Also, Siegel's Space is described as the set of anti-involutions of the symplectic group.2

Ethical banks: an Alternative in the Financial Crisis

This paper studies the differences between traditional financial intermediaries (commercial banks, saving banks and credit cooperatives) and ethical banks that focus on positive social and ethical values. The credit crisis calls into question the functionality and good performance of traditional banks. The full incorporation of ethical values and principles by traditional financial intermediaries might be a form to solve their misleading financial situation. We have analyzed four factors that theoretically mean ethical differences: information transparency, placement of assets, guarantees and participation. These four factors are grouped in an index called Radical Affinity Index (RAI). The paper is focused on the study of RAI using a sample of 119 European banks. The evidence shows, that transparency of information and placement of assets are factors that differentiate ethical banks and the rest of financial intermediaries. The guarantees and participation, which seemed to be useful factors to differentiate ethical aspects of banks, do not support clear evidence to the analysis. In sum, RAI is a functional and useful index to show the ethical policy of financial intermediaries

Renormalization Group Constraints on New Top Interactions from Electroweak Precision Data

Anomalous interactions involving the top quark contribute to some of the most difficult observables to directly access experimentally. They can give however a sizeable correction to very precisely measured observables at the loop level. Using a model-independent effective Lagrangian approach, we present the leading indirect constraints on dimension-six effective operators involving the top quark from electroweak precision data. They represent the most stringent constraints on these interactions, some of which may be directly testable in future colliders.Comment: 14 pages, 1 Table, 1 Figure. Minor changes, references added. Matches published versio

Extended Reissner-Nordstr\"om solutions sourced by dynamical torsion

We find a new exact vacuum solution in the framework of the Poincar\'e Gauge field theory with massive torsion. In this model, torsion operates as an independent field and introduces corrections to the vacuum structure present in General Relativity. The new static and spherically symmetric configuration shows a Reissner-Nordstr\"om-like geometry characterized by a spin charge. It extends the known massless torsion solution to the massive case. The corresponding Reissner-Nordstr\"om-de Sitter solution is also compatible with a cosmological constant and additional U(1) gauge fields.Comment: 12 pages, 0 figures, minor changes, references adde

New torsion black hole solutions in Poincar\'e gauge theory

We derive a new exact static and spherically symmetric vacuum solution in the framework of the Poincar\'e gauge field theory with dynamical massless torsion. This theory is built in such a form that allows to recover General Relativity when the first Bianchi identity of the model is fulfilled by the total curvature. The solution shows a Reissner-Nordstr\"om type geometry with a Coulomb-like curvature provided by the torsion field. It is also shown the existence of a generalized Reissner-Nordstr\"om-de Sitter solution when additional electromagnetic fields and/or a cosmological constant are coupled to gravity.Comment: 14 pages, 0 figures, minor changes, references adde

Einstein-Yang-Mills-Lorentz black holes

Different black hole solutions of the coupled Einstein-Yang-Mills equations have been well known for a long time. They have attracted much attention from mathematicians and physicists since their discovery. In this work, we analyze black holes associated with the gauge Lorentz group. In particular, we study solutions which identify the gauge connection with the spin connection. This ansatz allows one to find exact solutions to the complete system of equations. By using this procedure, we show the equivalence between the Yang-Mills-Lorentz model in curved space-time and a particular set of extended gravitational theories.Comment: 10 pages, 0 figures, minor changes, references added. It matches the version published in Eur. Phys. J.

Effective invariants of braid monodromy and topology of plane curves

In this paper we construct effective invariants for braid monodromy of affine curves. We also prove that, for some curves, braid monodromy determines their topology. We apply this result to find a pair of curves with conjugate equations in a number field but which do not admit any orientation-preserving homeomorphism.Comment: 26 pages, two EPS figures, LaTe