Coherent pion production off nuclei at T2K and MiniBooNE energies revisited

As a result of a new improved fit to old bubble chamber data of the dominant axial C_5^A nucleon-to-Delta form factor, and due to the relevance of this form factor for neutrino induced coherent pion production, we re-evaluate our model predictions in Phys. Rev. D79, 013002 (2009) for different observables of the latter reaction. Central values for the total cross sections increase by 20% to 30%, while differential cross sections do not change their shape appreciably. Furthermore, we also compute the uncertainties on total, differential and flux averaged cross sections induced by the errors in the determination of C_5^A. Our new results turn out to be compatible within about 1 sigma with the former ones. Finally, we stress the existing tension between the recent experimental determination of the sigma(CC coh \pi^+)/sigma(NC coh \pi^0) ratio by the SciBooNE Collaboration and the theoretical predictions.Comment: 6 latex pages, 1 table, 2 figures. Shortened versio

Radiative pion capture in nuclei: a continuum shell-model approach

The radiative pion capture process in nuclei is approached by using a continuum shell-model description of the nucleus, together with a phenomenological treatment of the two particle-two hole effects. It is found that these effects play an important role to reproduce the observed experimental photon energy distribution. This distribution as well as the integrated one depends significantly on the details of the mean field potential. This makes this process interesting to investigate the nuclear structure dynamics.Comment: 21 pages, LateX file + 5 figures, epsf.st

Study of semileptonic and nonleptonic decays of the Bc−B_c^- meson

We evaluate semileptonic and two--meson nonleptonic decays of the $B_c^-$ meson in the framework of a nonrelativistic quark model. The former are done in spectator approximation using one--body current operators at the quark level. Our model reproduces the constraints of heavy quark spin symmetry obtained in the limit of infinite heavy quark mass. For the two--meson nonleptonic decays we work in factorization approximation. We compare our results to the ones obtained in different relativistic approaches.Comment: Talk given at the IVth International Conference on Quarks an Nuclear Physics, Madrid, June 5th-10th 200

New determination of the NN-Δ(1232)\Delta(1232) axial form factors from weak pion production and coherent pion production off nuclei at T2K and MiniBooNE energies revisited

We re-evaluate our model predictions in Phys. Rev. D 79, 013002 (2009) for different observables in neutrino induced coherent pion production. This comes as a result of the new improved fit to old bubble chamber data of the dominant axial C_5^A nucleon-to-Delta form factor. We find an increase of 20%-30% in the values for the total cross sections. Uncertainties induced by the errors in the determination of C_5^A are computed. Our new results turn out to be compatible within about $1\sigma$ with the former ones. We also stress the existing tension between the recent experimental determination of the \sigma(CC coh \pi^+)}/\sigma(NC coh \pi^0)} $ ratio by the SciBooNE Collaboration and the theoretical predictions.Comment: 3 latex pages, 1 figure. Talk given at the NuFact10 Conferenc

Nucleon Emision Off Nuclei Induced By Neutrino Interactions

We make a review of the main nuclear effects that affect neutrino-nucleus cross sections. We discuss how the different models in the literature try to describe these different effects, and thus try to compare between them. We focus on the quasi-elastic reaction in the neutrino energy region of around 1 GeV, where recent data from MiniBoone are available. Among the issues discussed are the different treatment of medium corrections to initial and nal state nucleon wave functions and the problem of the rescattering of ejected nucleons.Comment: 5 pages, 5 figures. To appear in the proceedings for NuFact09; July 20-25, (2009) Illinois Institute of Technolog

Zc(3900)Z_c(3900): Confronting theory and lattice simulations

We consider a recent $T$-matrix analysis by Albaladejo {\it et al.}, [Phys.\ Lett.\ B {\bf 755}, 337 (2016)] which accounts for the $J/\psi\pi$ and $D^\ast\bar{D}$ coupled--channels dynamics, and that successfully describes the experimental information concerning the recently discovered $Z_c(3900)^\pm$. Within such scheme, the data can be similarly well described in two different scenarios, where the $Z_c(3900)$ is either a resonance or a virtual state. To shed light into the nature of this state, we apply this formalism in a finite box with the aim of comparing with recent Lattice QCD (LQCD) simulations. We see that the energy levels obtained for both scenarios agree well with those obtained in the single-volume LQCD simulation reported in Prelovsek {\it et al.} [Phys.\ Rev.\ D {\bf 91}, 014504 (2015)], making thus difficult to disentangle between both possibilities. We also study the volume dependence of the energy levels obtained with our formalism, and suggest that LQCD simulations performed at several volumes could help in discerning the actual nature of the intriguing $Z_c(3900)$ state

Non-universal gravitational couplings of neutrinos in matter

When neutrinos travel through a normal matter medium, the electron neutrinos couple differently to gravity compared to the other neutrinos, due to the presence of electrons in the medium and the absence of the other charged leptons. The matter-induced gravitational couplings of the neutrinos under such conditions are calculated and their contribution to the neutrino index of refraction in the presence of a gravitational potential is determined.Comment: Latex, 10 page

Neutrino induced coherent pion production

We discuss different parameterizations of the $C_5^A(q^2)$ $N\Delta$ axial form factor, fitted to the old Argonne bubble chamber data for pion production by neutrinos, and we use coherent pion production to test their low $q^2$ behavior. We find moderate effects that will be difficult to observe with the accuracy of present experiments. We also discuss the use of the Rein-Sehgal model for low energy coherent pion production. By comparison to a microscopic calculation, we show the weaknesses of some of the approximations in that model that lead to very large cross sections as well as to the wrong shapes for differential ones. Finally we show that models based on the partial conservation of the axial current hypothesis are not fully reliable for differential cross sections that depend on the angle formed by the pion and the incident neutrino.Comment: Talk given at NUFACT09. 6 latex pages, 7 figures, 1 tabl