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We present a model for the vector and axial form factors of the transitions B¯0→D** in good agreement with the presently available data and based on the present theoretical knowledge, combining (a) the safe lattice QCD predictions at mQ=∞ and w=1; (b) the predictions at general w of a relativistic, covariant quark model at mQ=∞, including the well-tested Godfrey and Isgur spectroscopic model and which agrees with lattice QCD at w=1; (c) the constraint of Bjorken and Neubert relating semileptonic and class I nonleptonic decays, which shows that B¯0→D0(2300)+π− strongly constrains τ1/2(w) to be much smaller than τ3/2(w), in agreement with the theoretical expectation; and (d) the general HQET expansion which constrains the 1/mQ corrections (cf. Leibovich et al. Phys. Rev. Lett. 78, 3995 (1997)., denoted hereafter as LLSW). An important element in the understanding of data is the large contribution of virtual DV(*) to the broad structures seen in SL decays at low D(*)π masses—which makes it difficult to isolate the broad resonances denoted as D1/2 in the following.

We present a model for the vector and axial form factors of the transitions $\overline{B}^0 \to D^{**}$ in good agreement with the presently available data and based on the present theoretical knowledge, combining a) the safe lattice QCD predictions at $m_Q=\infty$ and $w=1$ ; b) the predictions at general $w$ of a relativistic, covariant quark model at $m_Q=\infty$, including the well tested Godfrey and Isgur spectroscopic model and which agrees with lattice QCD at $w=1$ ; c) the constraint of Bjorken and Neubert relating Semi-leptonic (SL) and Class I Non-leptonic (NL) decays, which shows that $\overline{B}^0 \to D_0(2300)^{+} \pi^-$ strongly constrains $\tau_{1/2}(w)$ to be much smaller than $\tau_{3/2}(w)$, in agreement with the theoretical expectation; d) the general HQET expansion which constrains the $1/m_Q$ corrections (cf \cite{LLSW}, denoted hereafter as $LLSW$). An important element in the understanding of data is the large contribution of virtual $D^{(*)}_V$ to the broad structures seen in SL decays at low $D^{(*)} \pi$ masses - which makes it difficult to isolate the broad resonances denoted as $D_{1/2}$ in the following., Comment: revised version with modified formatting, references and comments (section II.B.c) added and errors corrected in the formulas of appendix (no impact on the numbers quoted in main text)

Motivated by the calculation of observables in the decays Λb→Λc(12±)ℓν¯, we present a calculation of form factors in the quark model. Our scheme combines a spectroscopic model with the internal wave functions and the Bakamjian-Thomas (BT) relativistic formalism to get the wave functions in motion. In the heavy quark limit, the current matrix elements provide the Isgur-Wise (IW) function. This limit is covariant, satisfies a large set of sum rules, and has been successfully applied to mesons. On the other hand, for baryons, we meet difficulties using standard spectroscopic models. This leads us to propose a phenomenological model, a Q-pointlike-diquark model, nonrelativistic, with harmonic oscillator forces, giving both a reasonable low-lying spectrum and the expected slope of the IW function. To begin, we extract this slope from lattice QCD data and find it to be around ρΛ2∼2, that we use as a guideline. We are not able to reproduce the right ρΛ2 using certain typical standard linear+Coulomb potential models, both with three quarks Qqq or in a Q-pointlike-diquark picture. These difficulties seem to derive from the high sensitivity of ρΛ2 to the structure of the light quark subsystem in a relativistic scheme. Finally, we present our model, and fixing its parameters to yield the correct spectrum and ρΛ2∼2, we apply it to the calculation of observables. By studying Bjorken sum rule, we show that the inelastic IW function is large, and therefore, the transitions Λb→Λc(12−,32−)ℓν¯ could be studied at LHCb. Interestingly, some observables in the τ case present zeroes for specific values of q2 that could be tests of the Standard Model.

Oral treatment of affirmative sentences is very different from the oral treatment of negative sentences. The latter particularly calls for rapid and effective inhibitory processes. We first focus on the affirmative form before inhibiting it to deal with negative markers : only then we get to the meaning of the negative sentence. Moreover, one of the main explanatory theories considers the inhibition deficit at the center of ADHD. We are trying to see here whether the inhibition deficit affects performance in processing negative sentences in an ADHD child compared to a child without ADHD. The results show that the child with ADHD makes more mistakes in processing negative sentences, by designating the affirmative counterparts of these sentences. On the other hand, its processing time is slower, illustrating a higher cognitive cost. The lack of inhibition appears to be closely correlated with these power performances. Other lines of approach seem to emerge through cvariables such as mental flexibility and fluid reasoning index.; Le traitement oral de phrases affirmatives est bien différent du traitement oral de phrases négatives. Ce dernier fait particulièrement appel à des processus inhibiteurs rapides et efficaces. Nous nous concentrons d’abord sur la forme affirmative avant de l’inhiber pour traiter les marqueurs négatifs : c’est alors que nous accédons au sens de la phrase négative. Or, l’une des principales théories explicatives place le déficit d’inhibition au centre du TDAH. Nous tentons de voir ici si ce déficit d’inhibition altère les performances en traitement de phrases négatives chez un enfant TDAH en comparaison à un enfant sans TDAH. Les résultats obtenus montrent que l’enfant avec TDAH commet plus d’erreurs de traitement de phrases négatives, en désignant les homologues affirmatives de ces phrases. Son temps de traitement est quant à lui plus lent, illustrant un coût cognitif plus important. Le défaut d’inhibition semble être étroitement corrélé avec ces performances moins bonnes. D’autres pistes de réflexion semblent se dégager à travers des variables telles que la flexibilité mentale et l’indice de raisonnement fluide.

Motivated by the calculation of observables in the decays $\Lambda_b \to \Lambda_c\left({1 \over 2}^\pm \right) \ell \overline{\nu}$, as tests of Lepton Flavor Universality, we present a calculation of form factors in the quark model. Our scheme combines a spectroscopic model, providing the internal wave functions, and the Bakamjian-Thomas relativistic formalism to deduce the wave functions in motion and current matrix elements, that amount in the heavy quark limit to the Isgur-Wise (IW) function. For baryons we meet difficulties using standard spectroscopic models, leading us to propose a simple phenomenological model : a Q-pointlike-diquark model, non-relativistic with harmonic oscillator forces, with a reasonable low-lying spectrum and good slope of the IW function. We extract this slope from Lattice data and find $\rho_\Lambda^2 \sim 2$. We are not able to reproduce the right $\rho_\Lambda^2$ when using standard linear + Coulomb potential models, both with three quarks $Qqq$ or in a Q-pointlike-diquark picture. These difficulties seem to derive from the high sensitivity of $\rho_\Lambda^2$ to the structure of the light quark subsystem. After fixing the parameters of our interim model to yield correct spectrum and $\rho_\Lambda^2$, we compute observables. Bjorken sum rule shows that the inelastic IW function is large, and therefore $\Lambda_b \to \Lambda_c \left({1 \over 2}^-, {3 \over 2}^- \right) \ell \overline{\nu}$ could be studied at LHCb. Some observables in the $\tau$ case present zeroes for specific values of $q^2$ that could be tests of the Standard Model., Comment: 62 pages, 30 figures

We stress that, although the D¯* is very narrow (one hundred keV), the difference between the full D¯* contribution to B→D¯ππ and its zero-width limit is surprisingly large: several percent. This phenomenon is a general effect that appears when considering the production of particles that are coupled to an intermediate virtual state, stable or not, and it persists whether the width is large or not. The effects of various cuts and of the inclusion of damping factors at the strong and weak vertices are discussed. It is shown how the zero-width limit, needed to compare with theoretical expectations, can be extracted. One also evaluates the virtual D¯V* contribution, which comes out roughly as found experimentally, but which is however much more dependent on cuts and uncontrollable off-shell effects. We suggest a way to estimate the impact of the damping factors.

We stress that, although the $D^*$ is very narrow (one hundred of keV), the difference between the full $D^*$ contribution to $B \to \bar{D} ����$ and its zero width limit, which stems from the resonance tail, is surprisingly large~: several percents. This phenomenon is a general effect which appears when considering the production of particles that are coupled to an intermediate virtual state, stable or not, and it persists whether the width is large or not. The effects of various cuts and of the inclusion of damping factors at the strong and weak vertices are discussed. It is shown how the zero width limit, needed to compare with theoretical expectations, can be extracted. One also evaluates the virtual $D^*_V$ contribution, which comes out roughly as expected from theory, but which is however much more dependent on cuts and uncontrollable "off-shell" effects. We suggest a way to estimate the impact of the damping factors., 26 pages, 7 figures. Second version with corrected numbers in tables, minor corrections and one Appendix added

Semileptonic transitions $\overline{B} \to D^{(n)} \ell \overline{\nu}$, where $D^{(n)} (n \not = 0)$ is a radially excited meson, have recently attracted much attention as a way to understand some puzzles between theory and data. Following closely the formalism of Falk and Neubert for the elastic case, we study the $1/m_Q$ corrections to the heavy quark limit, in which the inelastic Isgur-Wise function vanishes at zero recoil, $\xi^{(n)}(1) = 0\ (n \not = 0)$. We find simple formulas that involve the derivative $\xi^{(n)'}(1)$, and we propose a number of ways of isolating this quantity in practice. We formulate also a generalization to the inelastic case of Luke's theorem. On the other hand, although some $1/m_Q$ HQET results are satisfied in the Bakamjian-Thomas relativistic quark model, we emphasize the problems concerning these corrections in this scheme.

Motivated by the claimed possibility of a large contribution of the first radial excitation of the $D^{(\ast )}$ to the $B$ semileptonic decay into charmed mesons, also invoked to solve the "$1/2$ vs. $3/2$ semileptonic puzzle", we discuss the transitions to heavy-light radial excitations by a heavy $b \to c$ quark current. We first consider a HQET sum rule, which provides a bound on the slopes of Isgur-Wise functions which we then calculate in the Bakamjian-Thomas framework which both guaranties covariance in the heavy quark limit and satisfies a set of HQET sum rules. We observe a remarkable property that for a large variety of wave functions the transition to the first radial excitation is very small while the transition matrix element to the second radial excitation is large and dominant in saturating the HQET sum rule. This is opposite to what is found in non-relativistic models, where the transition to the first radial excitation dominates the sum rule. The relative magnitude of the transition to the second excitation appears to be weakly dependent on the dynamical scale (radius of the bound states), and the same holds true for the slope of the elastic transition. These features could be tested in the heavy mass limit of lattice QCD. This pattern is shown to be related to the general structure of the Bakamjian-Thomas model, it is independent of the spin structure of the approach and derives mainly from the Lorentz transformation of the spatial wave function, a feature often disregarded in quark models., Comment: 21 pages

Semileptonic transitions $\overline{B} \to D^{(n)} \ell \overline{\nu}$, where $D^{(n)} (n \not = 0)$ is a radially excited meson, have recently attracted much attention as a way to understand some puzzles between theory and data. Following closely the formalism of Falk and Neubert for the elastic case, we study the $1/m_Q$ corrections to the heavy quark limit, in which the inelastic Isgur-Wise function vanishes at zero recoil, $\xi^{(n)}(1) = 0\ (n \not = 0)$. We find simple formulas that involve the derivative $\xi^{(n)'}(1)$, and we propose a number of ways of isolating this quantity in practice. We formulate also a generalization to the inelastic case of Luke's theorem. On the other hand, although some $1/m_Q$ HQET results are satisfied in the Bakamjian-Thomas relativistic quark model, we emphasize the problems concerning these corrections in this scheme., Comment: 13 pages

We propose a model independent extraction of the hadronic information needed to determine the photon polarization of the b-> s gamma process by the method utilizing the B -> K1 gamma -> K pi pi gamma angular distribution. We show that exactly the same hadronic information can be obtained by using the B -> J/psi K1 -> J/psi K pi pi channel, which leads to a much higher precision., Comment: 12 pages, 1 figure

We propose a model independent extraction of the hadronic information needed to determine the photon polarization of the b→sγ process by the method utilizing the B→K1γ→Kππγ angular distribution. We show that exactly the same hadronic information can be obtained by using the B→J/ψK1→J/ψKππ channel, which leads to a much higher precision.