2,492 research outputs found
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 meson
We evaluate semileptonic and two--meson nonleptonic decays of the
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 - 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 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
: Confronting theory and lattice simulations
We consider a recent -matrix analysis by Albaladejo {\it et al.}, [Phys.\
Lett.\ B {\bf 755}, 337 (2016)] which accounts for the and
coupled--channels dynamics, and that successfully describes the
experimental information concerning the recently discovered .
Within such scheme, the data can be similarly well described in two different
scenarios, where the 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 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 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
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
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