Abstract: The masses of the D*(s0) (2317) and D-s1(2460) resonances lie below the DK and D* K thresholds respectively, which contradicts the predictions of naive quark models and points out to non-negligible effects of the D(*) K loops in the dynamics of the even-parity scalar (J(pi) = 0(+)) and axial-vector (J(pi) = 1(+)) c (s) over bar systems. Recent lattice QCD studies, incorporating the effects of the D(*) K channels, analyzed these spin-parity sectors and correctly described the D*(s0)(2317) – D-s1(2460) mass splitting. Motivated by such works, we study the structure of the D*(s0)(2317) and D-s1(2460) resonances in the framework of an effective field theory consistent with heavy quark spin symmetry, and that incorporates the interplay between D(*) K meson-meson degrees of freedom and bare P-wave c (s) over bar states predicted by constituent quark models. We extend the scheme to finite volumes and fit the strength of the coupling between both types of degrees of freedom to the available lattice levels, which we successfully describe. We finally estimate the size of the D(*) K two-meson components in the D*(s0)(2317) and D-s1(2460) resonances, and we conclude that these states have a predominantly hadronic-molecular structure, and that it should not be tried to accommodate these mesons within c (s) over bar constituent quark model patterns.

Abstract: The N Delta axial form factors are determined from neutrino induced pion production ANL and BNL data by using a theoretical model that accounts both for background mechanisms and deuteron effects. We find violations of the off-diagonal Goldberger-Treiman relation at the level of 2 sigma which might have an impact in background calculations for T2K and MiniBooNE low energy neutrino oscillation precision experiments.

Abstract: The production of the X (3872) as a hadronic molecule in hadron colliders is clarified. We show that the conclusion of Bignamini et al., Phys. Rev. Lett. 103 (2009) 162001, that the production of the X(3872) at high pT implies a non-molecular structure, does not hold. In particular, using the well understood properties of the deuteron wave function as an example, we identify the relevant scales in the production process.

Abstract: The so far only known charmed non-strange scalar meson is dubbed as D-0(*)(2400) in the Review of Particle Physics. We show, within the framework of unitarized chiral perturbation theory, that there are in fact two (I = 1/2, J(P) = 0(+)) poles in the region of the D-0(*)( 2400) in the coupled-channel D pi, D eta and D-s (K) over bar scattering amplitudes. With all the parameters previously fixed, we predict the energy levels for the coupled-channel system in a finite volume, and find that they agree remarkably well with recent lattice QCD calculations. This successful description of the lattice data is regarded as a strong evidence for the two-pole structure of the D-0(*)( 2400). With the physical quark masses, the poles are located at (2105(-8)(+6) – i102(-12)(+10)) MeV and (2451(-26)(+36) – i134(-8)(+7)) MeV, with the largest couplings to the D pi and D-s (K) over bar channels, respectively. Since the higher pole is close to the D-s (K) over bar threshold, we expect it to show up as a threshold enhancement in the D-s (K) over bar invariant mass distribution. This could be checked by high-statistic data in future experiments. We also show that the lower pole belongs to the same SU(3) multiplet as the D-s0(*)(2317) state. Predictions for partners in the bottom sector are also given.

Abstract: The study of pion production in nuclei is important for signal and background determinations in current and future neutrino oscillation experiments. The first step, however, is to understand the pion production reactions at the free nucleon level. We present an exhaustive study of the charged-current and neutral-current neutrino and antineutrino pion production off nucleons, paying special attention to the angular distributions of the outgoing pion. We show, using general arguments, that parity violation and time-reversal odd correlations in the weak differential cross sections are generated from the interference between different contributions to the hadronic current that are not relatively real. Next, we present a detailed comparison of three state-of-the-art, microscopic models for electroweak pion production off nucleons, and we also confront their predictions with polarized electron data, as a test of the vector content of these models. We also illustrate the importance of carrying out a comprehensive test at the level of outgoing pion angular distributions, going beyond comparisons done for partially integrated cross sections, where model differences cancel to a certain extent. Finally, we observe that all charged and neutral current distributions show sizable anisotropies, and identify channels for which parity-violating effects are clearly visible. Based on the above results, we conclude that the use of isotropic distributions for the pions in the center of mass of the final pion-nucleon system, as assumed by some of the Monte Carlo event generators, needs to be improved by incorporating the findings of microscopic calculations.