No Arabic abstract
The neutrino-nucleon --> lepton pion QE reaction on the A-target is used as a signal event or/and to reconstruct the neutrino energy, using two-body kinematics. Competition of another processes could lead to misidentification of the arriving neutrinos, being important the fake events coming from the CC1-pion background. A precise knowledge of cross sections is a prerequisite in order to make simulations in event generators to substract the fake ones from the QE countings, and in this contribution we analyze the different nuclear effects on the CC1-pion channel. Our calculations also can be extended for the NC case.
MiniBooNE [1] and MINERvA [2] charge current {pi} + production data in the Delta region are discussed. It is argued that despite the differences in neutrino flux they measure the same dynamical mechanism of pion production and should be strongly correlated. The correlation is clearly seen in the Monte Carlo simulations done with NuWro generator but is missing in the data. Both normalization and the shape of the ratio of measured differential cross sections in pion kinetic energy are different from the Monte Carlo results, in the case of normalization a discrepancy is by a factor of 1.49.
The total neutron-Nucleus cross section has been calculated within an approach which takes into account nucleon-nucleon correlations, Glauber multiple scattering and inelastic shadowing corrections. Nuclear targets ranging from 4He to 208Pb and neutron incident momentum ranging from 3 to 300 GeV/c, have been considered. Correlations have been introduced by two different approaches leading to the same results. The commonly used approximation, consisting in treating nuclear effects only by a product of one-body densities, is carefully analyzed and it is shown that the effects of realistic correlations resulting from modern nucleon-nucleon interactions and realistic correlations resulting from realistic nucleon-nucleon interactions and microscopic ground state calculation of nuclear properties cannot be disregarded.
We report the results of a study aimed at quantifying the impact on the oscillation analysis of the uncertainties associated with the description of the neutrino-nucleus cross section in the two-particle--two-hole sector. The results of our calculations, based on the kinematic method of energy reconstruction and carried out comparing two data-driven approaches, show that the existing discrepancies in the neutrino cross sections have a sizable effect on the extracted oscillation parameters, particularly in the antineutrino channel.
Heavy baryon chiral perturbation theory ($chi$PT), where the $Delta$ resonance is included, is used in order to examine the axial charged-current component of the weak interaction process at low neutrino energies. At leading chiral order the Adler theorems, derived using PCAC, are satisfied. At next-to-leading chiral order this effective field theory goes beyond these theorems. I will show that $chi$PT generates deviation from the PCAC predictions, which means that some neutrino-nucleon models that are used in evaluating neutrino nucleus scattering amplitudes, might need modifications.
Pauli blocking is carefully investigated for the processes of $NN rightarrow N Delta$ and $Delta rightarrow N pi$ in heavy-ion collisions, aiming at a more precise prediction of the $pi^-/ pi^+$ ratio which is an important observable to constrain the high-density symmetry energy. We use the AMD+JAM approach, which combines the antisymmetrized molecular dynamics for the time evolution of nucleons and the JAM model to treat processes for $Delta$ resonances and pions. As is known in general transport-code simulations, it is difficult to treat Pauli blocking very precisely due to unphysical fluctuations and additional smearing of the phase-space distribution function, when Pauli blocking is treated in the standard method of JAM. We propose an improved method in AMD+JAM to use the Wigner function precisely calculated in AMD as the blocking probability. Different Pauli blocking methods are compared in heavy-ion collisions of neutron-rich nuclei, ${}^{132}mathrm{Sn}+{}^{124}mathrm{Sn}$, at 270 MeV/nucleon. With the more accurate method, we find that Pauli blocking is stronger, in particular for the neutron in the final state in $NN rightarrow N Delta$ and $ Delta to Npi$, compared to the case with a proton in the final state. Consequently, the $pi^-/pi^+$ ratio becomes higher when the Pauli blocking is improved, the effect of which is found to be comparable to the sensitivity to the high-density symmetry energy.