Electromagnetic structure and weak decay of meson K in a light-front QCD-inspired

The kaon electromagnetic (e.m.) form factor is reviewed considering a light-front constituent quark model. In this approach, it is discussed the relevance of the quark-antiquark pair terms for the full covariance of the e.m. current. It is also verified, by considering a QCD dynamical model, that a good agreement with experimental data can be obtained for the kaon weak decay constant once a probability of about 80% of the valence component is taken into account.Comment: 4 pages and 1 figure eps. To appear Nucl. Phys. A (2007

The sigmatic future and the genetic affiliation of Venetic: Latin faxo 'I shall make' and Venetic vha.g.s.to 'he made'

Latin has a so-called sigmatic future faxo 'I shall make'. Scholars are divided as to the origins and antiquity of faxo; some believe it to go back to desideratives, others to aorists, and some argue that the formation arose within Latin, others that it can be traced back to Proto-Italic. Closely connected with these problems are the questions whether Venetic is an Italic language and whether its past ('aorist') tense vha.g.s.to 'he made' is related to fax (o) over bar. I intend to show that fax (o) over bar is based on inherited s-aorists, not on desideratives, that the formation arose late, within Latin itself rather than within Proto-Italic, and that there was never a past indicative beside it. Because of the last two reasons, vha.g.s.to must be independent of fax (o) over bar. Venetic may still be an Italic language, but the form vha.g.s.to cannot be used as an argument in favour of such a connection

Vertical Restraints Facilitating Horizontal Collusion: ‘Stretching’ Agreements in a Comparative Approach

This article discusses the approaches of the European Union (EU) and of the United States (US) to the notions of agreement and concerted practice applied to horizontal collusive consequences of vertical restraints. It concludes that networks of vertical restraints blur the differences between vertical and horizontal agreements; therefore, both options of attack are available for enforcers in the EU and the US context. If the analysed vertical restraints are adopted in parallel by agreement, they should be deemed illegal as long as they restrict competition producing collusive consequences. In the absence of explicit coordination to adopt the practice, I suggest first looking for a stretched concept of horizontal agreement or a broadly interpreted concept of concerted practice, including unilateral ‘communication’ that intentionally reduces uncertainty. Even when the analysed practices are adopted individually and not by all firms, they can represent a commitment to focal points, observable by market players, thus amounting to communication of intent. If that is not possible, I propose that an analysis of market power, incentives, coercion and induction should guide the finding of an illegal vertical agreement and ground the analysis of the consequences. The agreement/concerted practice path is an appropriate, feasible and coherent way to deal with vertical restraints facilitating horizontal tacit coordination, but that does not exclude alternative effective enforcement mechanisms

Light-Front Model of Transition Form-Factors in Heavy Meson Decay

Electroweak transition form factors of heavy meson decays are important ingredients in the extraction of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements from experimental data. In this work, within a light-front framework, we calculate electroweak transition form factor for the semileptonic decay of $D$ mesons into a pion or a kaon. The model results underestimate in both cases the new data of CLEO for the larger momentum transfers accessible in the experiment. We discuss possible reasons for that in order to improve the model.Comment: Paper with 5 pages and 2 eps figures. To appear to Nuclear Physics B. Talk at Light Cone 2009: Relativistic Hadronic and Particle Physics (LC 2009), Sao Jose dos Campos, S.P, Brazil, 8-13 Jul 2009

Rigidity of critical circle mappings, I

We prove that two $C^r$ critical circle maps with the same rotation number of bounded type are $C^{1+\alpha}$ conjugate for some $\alpha>0$ provided their successive renormalizations converge together at an exponential rate in the $C^0$ sense. The number $\alpha$ depends only on the rate of convergence. We also give examples of $C^\infty$ critical circle maps with the same rotation number that are not $C^{1+\beta}$ conjugate for any $\beta>0$