arXiv subjects
Publications and source records attributed to Krzysztof M. Graczyk.
This talk presents some of the results of the re-analysis of [Graczyk et al.] of the bubble chamber data for single pion production induced by neutrino scattering off deuteron. It is shown that ANL and BNL data are statistically consistent. The validity of the Adler relations (between $P_{33}(1232)$ resonance axial form factors) is also investigated.
$C_5^A(Q^2)$ axial form factor is extracted from the ANL neutrino-deuteron scattering data with deuteron structure effects taken into consideration. The best fit of the $C_5^A(Q^2)$ axial form factor is obtained assuming dipole parametrization with $C_5^A(0)=1.13\pm0.15$ and $M_A=0.94\pm 0.08$ GeV.
Single pion production in neutrino-nucleon scattering is discussed. The neutrino energies characteristic for T2K project are considered. Two new parameterizations of $C_5^A$ axial form factor are proposed. Both of them are obtained in simultaneous fit to ANL and BNL data. One of them (which fits better to BNL data) leads to $dσ/dQ^2$ differential cross section which is significantly reduced at low $Q^2$.
Different approaches to take into account nonzero lepton mass in the Rein-Sehgal model are compared. Modification of the axial current due to pion pole term are included and it is shown that they lead to large reduction of antineutrino cross section and a change of the shape of $dσ/dQ^2$.
The quark-hadron duality in CC and NC neutrino interactions is discussed under assumptions that single pion production is described accurately by the Rein-Sehgal model and that it allows reconstruction of the inclusive cross section in the resonance region. The duality is measured by means of integrals of structure functions in the Nachtmann variable for $Q^2<3$ GeV$^2$. The results depend on the precision with which contributions from single pion production channels in the overall cross sections are known. Several approaches to evaluate them are compared. The duality is predicted to be seen for proton target reactions and to be absent for neutron and isoscalar targets. Two-component duality between resonant and valence quark contributions to structure functions is also investigated.
Quark-hadron duality in neutrino-nucleon reactions is investigated under the assumption that cross sections in the resonance region are given by the Rein-Sehgal model. The quantitative analysis of the duality is done by means of appropriate integrals of the structure functions in the Nachtmann variable. We conclude that with the definition of the resonance region $W\in (M+m_π, 2$ GeV) the duality holds for neutrino-proton reaction $F_2$ structure function for $Q^2\in (0.5, 3)$ GeV$^2$ and it is absent for neutrino-neutron reaction.
The quasielastic charged-current (CC) tau neutrino (antineutrino)-nucleus scattering is considered. The dependence of tau polarization on nuclear-structure effects is discussed in detail. The description of the nucleus is based on the Mean-Field Theory (MFT). The ground state of nucleus is described using the Relativistic Fermi Gas model (FG). The effective mass is introduced as well as the ring Random Phase Approximation (RPA) effects are taken into account in the framework of relativistic meson-nucleon model. The Local Density Approximation (LDA) is used for the argon nucleus, having in mind possible application to the ICARUS experiment. The discussion concentrates on the threshold region where the $τ^-$ can be unpolarized and the nuclear effects play an important role.
Numerical results for the degree of polarization of τ^- produced in (CC) neutrino - nucleon Deep Inelastic Scattering (DIS) are presented. Calculations are done in the threshold region, where the τ^- scattered by the small angles and can be partially polarized. The cross sections and polarization are calculated by using the GRV98 parton distributions functions (PDF's) and the GRV98 with modifications of A. Bodek at.al.
We constructed a new Monte Carlo generator of events for neutrino CC single pion production on free nucleon targets. The code uses dynamical models of the DIS with the PDFs modified according to the recent JLab data and of the Delta excitation. A comparison with experimental data was done in three channels for the total cross sections and for the distributions of events in invariant hadronic mass.
Numerical computations of cross sections for quasielastic charge current scattering of neutrino on Oxygen, Argon and Iron in Local Density Approximation (LDA) are presented. We consider processes for a few GeV neutrino energy. We include corrections from nucleon re-interaction in nucleus described by relativistic Random Phase Approximation (RPA). We adopt the relativistic Fermi gas model of nucleus with and without taking into account the effective mass of nucleons.
The algebraic solution of RPA equations nucleon re-interactions in the case of quasi elastic charged current neutrino - nucleus scattering is presented. Abelian algebra of matrices allows to extract four independent corrections to cross section separatly.Results of numerical computations are shown.