Remarks on sum rules in the heavy quark limit of QCD

We underline a problem existing in the heavy quark limit of QCD concerning the rates of semileptonic B decays into P-wave $D_J(j)$ mesons, where $j = {1 \over 2}$ (wide states) or $j = {3 \over 2}$ (narrow states). The leading order sum rules of Bjorken and Uraltsev suggest $\Gamma [ \bar{B} \to D_{0,1} ({1 \over 2}) \ell \nu ] \ll \Gamma [ \bar{B} \to D_{1,2} ({3 \over 2}) \ell \nu ]$, in contradiction with experiment. The same trend follows also from a sum rule for the subleading $1/m_Q$ curent matrix element correction $\xi_3(1)$. The problem is made explicit in relativistic quarks models \`a la Bakamjian and Thomas, that give a transparent physical interpretation of the latter as due, not to a $L \cdot S$ force, but to the Wigner rotation of the light quark spin. We point out moreover that the selection rule for decay constants of $j = {3 \over 2}$ states, $f_{3/2} = 0$, predicts, assuming the model of factorization, the opposite hierarchy $\Gamma [ \bar{B} \to \bar{D}_{s_{1,2}} ({3 \over 2}) D^{(*)} ] \ll \Gamma [ \bar{B} \to \bar{D}_{s_{0,1}} ({1 \over 2}) D^{(*)} ]$.Comment: Contribution to the International Europhysics Conference on HEP, Budapest, July 2001 (presented by L. Oliver); 5 page

Phenomenological discussion of B→PVB\to P V decays in QCD improved factorization approach

Trying a global fit of the experimental branching ratios and CP-asymmetries of the charmless $B\to PV$ decays according to QCD factorization, we find it impossible to reach a satisfactory agreement, the confidence level (CL) of the best fit is smaller than .1 %. This failure reflects the difficulty to accommodate several large experimental branching ratios of the strange channels. Furthermore, experiment was not able to exclude a large direct CP asymmetry in $\bar {B}^0\to\rho^+ \pi^-$, which is predicted very small by QCD factorization. Proposing a fit with QCD factorization complemented by a charming-penguin inspired model we reach a best fit which is not excluded by experiment (CL of about 8 %) but is not fully convincing. These negative results must be tempered by the remark that some of the experimental data used are recent and might still evolve significantly.Comment: 8 pages, 2 figures (requires epsfig, psfrag),talk presented at the XXXVIIIth Rencontres de Moriond: Electroweak Interactions and Unified Theories,Les Arcs, France, March 15-22, 2003. To be published in the Proceeding

Ghost-gluon coupling, power corrections and ΛMSˉ\Lambda_{\bar{MS}} from twisted-mass lattice QCD at Nf=2N_f=2

A non-perturbative calculation of the ghost-gluon running QCD coupling constant is performed using $N_f=2$ twisted-mass dynamical fermions. The extraction of $\Lambda_{\bar{MS}}$ in the chiral limit reveals the presence of a non-perturbative OPE contribution that is assumed to be dominated by a dimension-two \VEV{A^2} condensate. In this contest a novel method for calibrating the lattice spacing in lattice simulations is presented.Comment: 7 pages, 4 figures, XXVIII International Symposium on Lattice Field Theory 201

Referees´ visual behaviour during offside situations in football.

El estudio analiza el comportamiento visual de 8 árbitros de fútbol durante la percepción del fuera de juego en laboratorio. La tarea consiste en percibir una secuencia de 24 ensayos en una pantalla (5x3m), donde se proyectan situaciones reducidas de juego y que concluyen con una posible acción de fuera de juego. Los participantes deben percibir la secuencia con el ASL Eye Tracking SE5000, y pulsar un puntero laser hacia la pantalla en aquellos ensayos con fuera de juego. Las variables a manipular son la distancia y el ángulo con que se perciben las acciones de fuera de juego. Las variables dependientes son el número y tiempo (media) de fijaciones visuales y el porcentaje de acierto. Los resultados muestran que la distancia y ángulo influyen en el comportamiento visual de los árbitros. Además, son más eficaces detectando el fuera de juego con ángulos pequeños y en distancias cercanas y medias.The study examines the 8 football referees´ visual behavior during the perception of offside actions carried out in a laboratory setting. The task consists on perceiving a rally of 24 trials onto a large screen (5x3m) with reduced play situations and that could conclude with an offside action. Participants perceive the sequence with the ASL Eye Tracking SE5000 and press a laser pointer toward the screen in those trials with offside action. Variables to manipulate are the distance and angle in which the offside trials are perceived. The dependent variables are the number and time (average) of visual fixations and the success rate. The results show that the distance and angle changes the referees´ visual behavior. Moreover, they have higher success rate when they perceive trials with small angles, concretely with short and medium distance

Renormalisation of quark propagators from twisted-mass lattice QCD at NfN_f=2

We present results concerning the non-perturbative evaluation of the renormalisation constant for the quark field, $Z_q$, from lattice simulations with twisted mass quarks and three values of the lattice spacing. We use the RI'-MOM scheme. $Z_q$ has very large lattice spacing artefacts; it is considered here as a test bed to elaborate accurate methods which will be used for other renormalisation constants. We recall and develop the non-perturbative correction methods and propose tools to test the quality of the correction. These tests are also applied to the perturbative correction method. We check that the lattice spacing artefacts scale indeed as $a^2p^2$. We then study the running of $Z_q$ with particular attention to the non-perturbative effects, presumably dominated by the dimension-two gluon condensate \VEV{A^2} in Landau gauge. We show indeed that this effect is present, and not small. We check its scaling in physical units confirming that it is a continuum effect. It gives a $\sim 4$ contribution at 2 GeV. Different variants are used in order to test the reliability of our result and estimate the systematic uncertainties. Finally combining all our results and using the known Wilson coefficient of \VEV{A^2} we find g^2(\mu^2) \VEV{A^2}_{\mu^2\; CM} = 2.01(11)(^{+0.61}_{- 0.73}) \;\mathrm {GeV}^2 at $\mu=10\, \mathrm{GeV}$, in fair agreement within uncertainties with the value indepently extracted from the strong coupling constant.Comment: 38 pages, 8 tables, 8 figure

Ghost-gluon coupling, power corrections and ΛMS‾\Lambda_{\overline {\rm MS}} from twisted-mass lattice QCD at Nf=2

We present results concerning the non-perturbative evaluation of the ghost-gluon running QCD coupling constant from $N_f=2$ twisted-mass lattice calculations. A novel method for calibrating the lattice spacing, independent of the string tension and hadron spectrum is presented with results in agreement with previous estimates. The value of $\Lambda_{\overline{MS}}$ is computed from the running of the QCD coupling only after extrapolating to zero dynamical quark mass and after removing a non-perturbative OPE contribution that is assumed to be dominated by the dimension-two \VEV{A^2} gluon condensate. The effect due to the dynamical quark mass in the determination of \Lams is discussed.Comment: 33 pages, 6 fig

A Few Aspects of Heavy Quark Expansion

Two topics in heavy quark expansion are discussed. The heavy quark potential in perturbation theory is reviewed in connection to the problem of the heavy quark mass. The nontrivial reason behind the failure of the "potential subtracted" mass in higher orders is elucidated. The heavy quark sum rules are the second subject. The physics behind the new exact sum rules is described and a simple quantum mechanical derivation is given. The question of saturation of sum rules is discussed. A comment on the nonstandard possibility which would affect analysis of BR_sl(B) vs. n_c is made.Comment: 21 pages, LaTeX, 7 eps figures. To appear in the Proceedings of the UK Phenomenology Workshop on Heavy Flavour and CP Violation, Durham, UK, 17-22 September 200

Modular and Reconfigurable Platform as New Philosophy for the Development of Updatable Vehicular Electronics

[EN] A new conception in the development of Electronic Control Units (ECUs), which are also called On-Board Units (OBUs), is discussed in this paper from an ontological vision oriented to the compatibility of vehicles with future technologies in the automotive field. This work also provides a new methodology in the design of On-Board vehicle units. The proposed technique is based on the concept of modular electronic units that can change their functionality depending on the modules they are consisted of. The study was initially designed at the theoretical level, analysing the problems in the sector in the face of the coexistence between vehicles today and those that are bound to appear in the near future, and that will incorporate capabilities making them connected and even autonomous. Additionally, a fully operational prototype has been developed so as to ascertain the possibilities of the proposed solution.[ES] Se presenta una nueva concepción en el desarrollo de Unidades Electrónicas de Control (ECU), también denominadas Unidades de a Bordo (OBU), desde una visión ontológica orientada en la compatibilización de los vehículos con las futuras tecnologías emergentes en el campo de la automoción. Se comienza por un estudio teórico que analiza la problemática en el sector del transporte que va a presentar la convivencia entre los vehículos actuales y los que van a ir apareciendo en el futuro; y que vendrán influenciados por conceptos tales como los vehículos conectados o los vehículos autónomos. Este artículo también aporta una nueva metodología en el diseño de unidades vehiculares de a bordo, basada en el concepto de unidades electrónicas modulares que definen su funcionalidad en base a los módulos que le sean acoplados. Adicionalmente se ha desarrollado un prototipo completo y totalmente funcional con el fin de analizar las posibilidades de la solución propuesta.Este trabajo ha sido realizado parcialmente gracias al apoyo recibido mediante la resolución del 31/07/2014, publicada por la Universidad de Castilla-La Mancha, que establece las bases reguladoras de la convocatoria para contratos predoctorales con objeto de preparar nuevos investigadores bajo el Plan Propio de I+D+i. [2014/10340]Cañas, V.; García, A.; De Las Morenas, J.; Blanco, J. (2019). Plataforma Modular Reconfigurable como Nueva Filosofía para el Desarrollo de Electrónica Vehicular Actualizable. Revista Iberoamericana de Automática e Informática. 16(2):200-211. https://doi.org/10.4995/riai.2018.9863SWORD20021116

apeNEXT: A multi-TFlops Computer for Simulations in Lattice Gauge Theory

We present the APE (Array Processor Experiment) project for the development of dedicated parallel computers for numerical simulations in lattice gauge theories. While APEmille is a production machine in today's physics simulations at various sites in Europe, a new machine, apeNEXT, is currently being developed to provide multi-Tflops computing performance. Like previous APE machines, the new supercomputer is largely custom designed and specifically optimized for simulations of Lattice QCD.Comment: Poster at the XXIII Physics in Collisions Conference (PIC03), Zeuthen, Germany, June 2003, 3 pages, Latex. PSN FRAP15. Replaced for adding forgotten autho