'Bs --> Ds l nu' near zero recoil in and beyond the Standard Model

We compute the normalization of the form factor entering the Bs --> Ds l nu decay amplitude by using numerical simulations of QCD on the lattice. From our study with Nf=2 dynamical light quarks, and by employing the maximally twisted Wilson quark action, we obtain in the continuum limit G(1) = 1.052(46). We also compute the scalar and tensor form factors in the region near zero recoil and find f0(t0)/f+(t0)=0.77(2), fT(t0,mb)/f+(t0)=1.08(7), for t0=11.5 GeV^2. These latter results are useful for searching the effects of physics beyond the Standard Model in Bs --> Ds l nu decays. Our results for the similar form factors relevant to the non-strange case indicate that the method employed here can be used to achieve the precision determination of the B --> D l nu decay amplitude as well.Comment: 17 pages (6 tables, 6 plots), published versio

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

The controversy about "1/m_Q duality violation" ; a quark model point of view

A detailed discussion based on exact calculations, possible in the non relativistic quark model, is given to show that there is no 1/m_Q term in the heavy quark expansion of totally integrated semileptonic decay rates. More generally, it is shown that OPE holds with very few terms in the expansion, at least in the harmonic oscillator model.Comment: 10 pages, full articl

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

Santiago de Compostela, 1850-1950: desenvolvemento urbano outra arquitectura

Prólogo de Pedro Navascués Palaci

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

Testing OPE for ghosts, gluons and αs\alpha_s

We present here our results on extracting Wilson coefficients from different quantities such as ghost and gluon propagators which are calculated by means of Lattice QCD. The results confirm the validity of our method for the calculation of the strong coupling constant as well as allow to estimate the range of momenta where OPE is applicable.Comment: arXiv admin note: substantial text overlap with arXiv:1301.759

Obras de rehabilitación en el Mercado de Abastos de la ciudad histórica de Santiago de Compostela

The historic value of the provision markets, both in Santiago and in other places in Spain, can be synthesized in a study carried out in Santiago through different works of rehabilitation of its Provision Market. A detailed description is given of the Market grounds -in the mid-XIX century-, of the consequences of its location, and the environmental shock produced. The article ends by commenting on the work of Vaquero Palacios on the present state of the Market and the rehabilitation actions taken.El valor histórico de lo que significaban las mercaderías de abasto, tanto en Santiago como en los distintos puntos de nuestra geografía, puede sintetizarse a través del estudio llevado a cabo en dicha ciudad mediante las distintas obras de rehabilitación de su Mercado de Abastos. Se hace una descripción pormenorizada del enclave de este Mercado -a mediados del XIX-, de las consecuencias de su emplazamiento y del choque ambiental producido. Finaliza este artículo comentando la obra de Vaquero Palacios sobre el estado del actual Mercado y las obras de intervención y rehabilitación realizadas

Calidad en los servicios de turismo activo de Extremadura

El objetivo del estudio fue analizar la calidad emitida del servicio de actividades físicas en la naturaleza por parte de trabajadores de empresas extremeñas de turismo activo. Complementariamente, se analizó si la calidad percibida de dicho servicio estaba influida por el rol del trabajador, gerente o monitor deportivo, dentro de la empresa. La muestra de participantes estaba compuesta por 25 trabajadores: 16 monitores y 9 gerentes. Para estudiar la calidad del se utilizó el cuestionario validado por Mediavilla (2013). Los resultados mostraron diferencias en ambas variables de estudio (importancia y valoración del ítem). Específicamente, los gerentes dieron más importancia y valoraron más las cuestiones relativas a la calidad ya que puntúan con mayor valor los ítems incluidos en el cuestionario (p < 0.001). Las tareas derivadas del ejercicio profesional en trabajadores de empresas de turismo activo influyen en la percepción de calidad con que se presta el servicio de actividades físicas en la naturaleza. Estos resultados han permitido conocer los bloques de preguntas que recibieron una mayor o menor puntuación, así como localizar las diferencias entre grupos. Se recomienda prestar atención a aquellos ítems o preguntas que tuvieron una puntuación más baja, analizando las causas e implementando propuestas concretas de trabajo para mejorar su relación con la percepción de calidad en el servicio prestado