Search

The charged current (anti)neutrino induced eta production from the nucleons is studied in a model based on the effective Lagrangians to evaluate the contribution from the nonresonant and resonant diagrams. The contribution from the nonresonant background terms has been obtained using a microscopic model based on the SU(3) chiral Lagrangians. The contribution from the resonant diagrams due to the low lying S11(1535), S11(1650), and P11(1710) resonances has been evaluated using an effective phenomenological Lagrangian with its parameters determined from the experimental values of their branching ratios and decay widths to the Nη channel. The model is first used to reproduce satisfactorily the experimental data from the MAINZ and JLab on the total cross sections for the photo- and electro- production of η mesons, which fixes the model parameters in the vector current interaction. The partially conserved axial vector current (PCAC) hypothesis and generalized Goldberger-Treiman relation are used to fix the parameters of the axial vector current interaction. The model is then applied to study the weak production of eta mesons induced by the neutrinos and antineutrinos, and predicts the numerical values for the Q2-distribution, η-momentum distribution, and the total cross section for the reactions νμ+n→μ−+p+η and ν¯μ+p→μ++n+η in the energy region up to 2 GeV. It is found that the photo, electro, and (anti)neutrino induced production of eta mesons is dominated by the contribution from the S11(1535) resonance. The results discussed in this work are relevant for the present and future accelerator experiments like MicroBooNE, T2K, NOvA, MINERvA, T2-HyperK, and DUNE as well as for the atmospheric neutrino experiments.

The cross sections and polarization components of the $\ensuremath{\tau}$ leptons produced in the charged current induced quasielastic ${\ensuremath{\nu}}_{\ensuremath{\tau}}({\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}})\ensuremath{-}N$ scattering have been studied. The theoretical uncertainties arising due to the use of different vector form factors and the axial dipole mass in the axial vector form factor have been investigated. Due to the high mass of $\ensuremath{\tau}$ lepton, the contributions from the term containing pseudoscalar and second class current form factors are non-negligible and contribute to the uncertainty in the cross section and polarization observables as these form factors are not well known. In view of the currently proposed experiments by DUNE, SHiP, and DsTau collaborations to study the production of $\ensuremath{\tau}$ lepton, an updated calculation of the cross sections and polarizations of tau leptons in the case of quasielastic production have been done and the numerical results have been presented along with a discussion of the theoretical uncertainties.

The effect of nonperturbative and higher order perturbative corrections to all the free nucleon structure functions [${F}_{iN}(x,{Q}^{2});i=1--5$] in the deep inelastic scattering (DIS) of ${\ensuremath{\nu}}_{\ensuremath{\tau}}/{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ on nucleon is studied. The target mass correction and higher twist effects are incorporated following the works of Kretzer et al. and Dasgupta et al., respectively. The evaluation of the nucleon structure functions has been performed by using the Martin--Motylinski-- Harland-Lang--Thorne 2014 parametrization of the parton distribution functions. The calculations have been performed at the next-to-leading order. These nucleon structure functions are used to calculate the DIS cross section by further including the kinematical corrections due to $\ensuremath{\tau}$-lepton mass. Due to the inclusion of lepton mass two additional structure functions ${F}_{4N}(x,{Q}^{2})$ and ${F}_{5N}(x,{Q}^{2})$ become non-negligible. The results for the nucleon structure functions, differential and total scattering cross sections are presented. The various effects considered in this work are effective in the different regions of $x$ and ${Q}^{2}$, and quite important in the energy region of ${E}_{{\ensuremath{\nu}}_{\ensuremath{\tau}}/{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}}l15\text{ }\text{ }\mathrm{GeV}$. A comparative study of our results with the existing results in the literature for the cross sections is made in the energy region of interest for the DUNE, SHiP, DsTau and HyperK experiments proposed to be done in the near future.

We study the effect of various perturbative and nonperturbative QCD corrections on the free nucleon structure functions [${F}_{iN}^{WI}(x,{Q}^{2});i=1--3$] and their implications in the determination of nuclear structure functions. The evaluation of the nucleon structure functions has been performed by using the MMHT 2014 parton distribution functions (PDFs) parametrization, and the target mass correction (TMC) and higher twist (HT) effects are incorporated following the works of Schienbein et al. and Dasgupta et al., respectively. These nucleon structure functions are taken as input in the determination of nuclear structure functions. The numerical calculations for the ${\ensuremath{\nu}}_{l}/{\overline{\ensuremath{\nu}}}_{l}\text{\ensuremath{-}}A$ deep inelastic scattering (DIS) process have been performed by incorporating the nuclear medium effects like Fermi motion, binding energy, nucleon correlations, mesonic contributions, shadowing, and antishadowing in several nuclear targets such as carbon, polystyrene scintillator, iron, and lead, which are being used in $\mathrm{MINER}\ensuremath{\nu}\mathrm{A}$, and in argon nuclei, which is relevant for the ArgoNeuT and DUNE experiments. The differential scattering cross sections $\frac{{d}^{2}{\ensuremath{\sigma}}_{A}^{WI}}{dxdy}$ and $(\frac{d{\ensuremath{\sigma}}_{A}^{WI}}{dx}/\frac{d{\ensuremath{\sigma}}_{CH}^{WI}}{dx})$ have also been studied in the kinematic region of the $\mathrm{MINER}\ensuremath{\nu}\mathrm{A}$ experiment. The theoretical results are compared with the recent experimental data of $\mathrm{MINER}\ensuremath{\nu}\mathrm{A}$ and the earlier data of the NuTeV, CCFR, CDHSW, and CHORUS Collaborations. Moreover, a comparative analysis of the present results for the ratio $(\frac{d{\ensuremath{\sigma}}_{A}^{WI}}{dx}/\frac{d{\ensuremath{\sigma}}_{CH}^{WI}}{dx})$, and the results from the Monte Carlo (MC) generator GENIE and other phenomenological models of Bodek and Yang, and Cloet et al., has been performed in the context of the $\mathrm{MINER}\ensuremath{\nu}\mathrm{A}$ experiment. The predictions have also been made for the ${\overline{\ensuremath{\nu}}}_{l}\text{\ensuremath{-}}A$ cross section relevant for the $\mathrm{MINER}\ensuremath{\nu}\mathrm{A}$ experiment.

The effect of the second class currents with and without time reversal invariance has been studied in the quasielastic production of nucleons and hyperons induced by neutrinos and antineutrinos from the nucleons. The numerical results are presented for the total scattering cross section~($\sigma$) as well as for the longitudinal, perpendicular and transverse components of the polarization of the final baryons ($p$, $n$, $\Lambda$, $\Sigma^-$, $\Sigma^0$) and muon produced in the quasielastic (anti)neutrino-nucleon scattering induced by the weak charged current. In the case of the production of $\Lambda$ hyperon, which is the most suitable candidate for making the polarization measurements, we have also calculated the $Q^2$ dependence of the polarization observables and the differential scattering cross section ($d\sigma/dQ^2$). The measurement of the polarization observables and their $Q^2$ dependence provides an independent way to determine the nucleon-hyperon transition form factors at high $Q^2$ which can provide tests of the symmetries of the weak hadronic currents like G-invariance, T invariance and SU(3) symmetry., Comment: 29 pages, 17 figures, 1 table

We have studied the differential cross section as well as the longitudinal and perpendicular components of polarization of final hyperon($\Lambda$,$\Sigma$) produced in the antineutrino induced quasielastic charged current reactions on nucleon and nuclear targets. The nucleon-hyperon transition form factors are determined from the experimental data on quasielastic $(\Delta S =0)$ charged current (anti)neutrino--nucleon scattering and the semileptonic decay of neutron and hyperons assuming G--invariance, T--invariance and SU(3) symmetry. The vector transition form factors are obtained in terms of nucleon electromagnetic form factors for which various parameterizations available in literature have been used. A dipole parameterization for the axial vector form factor and the pseudoscalar transition form factor derived in terms of axial vector form factor assuming PCAC and GT relation extended to strangeness sector have been used in numerical evaluations. The flux averaged cross section and polarization observables corresponding to CERN Gargamelle experiment have been calculated for quasielastic hyperon production and found to be in reasonable agreement with the experimental observations. The numerical results for the flux averaged differential cross section$\frac{d\sigma}{dQ^2}$ and longitudinal(perpendicular) polarization $P_L(Q^2)(P_P(Q^2))$ relevant for the antineutrino fluxes of MINER$\nu$A, MicroBooNE, and T2K experiments have been presented. This will be useful in interpreting future experimental results on production cross sections and polarization observables from the experiments on the quasielastic production of hyperons induced by antineutrinos and explore the possibility of determining the axial vector and pseudoscalar form factors in the strangeness sector., Comment: 23 Pages, 23 Figures

We have studied charged current $\bar\nu_l$ induced one pion production from $^{12}$C and $^{16}$O nuclear targets at MiniBooNE and atmospheric antineutrino energies. The calculations have been done for the incoherent pion production process as well as for the pions coming from the hyperons in the quasielastic production of $\Lambda$ and $\Sigma$. The calculations are done in the local density approximation. For the inelastic processes the calculations have been done in the $\Delta$ dominance model and we take into account the effect of Pauli blocking, Fermi motion of the nucleon and renormalization of $\Delta$ properties in the nuclear medium. The effect of final state interaction(FSI) of pions is also taken into account. For the hyperon production, the nuclear medium effects due to Fermi motion and FSI effects due to hyperon-nucleon scattering have been taken into account. These results may be quite useful in the analysis of SciBooNE, MicroBooNE, MINER$\nu$A, and ArgoNeuT experiments when the pion analysis is done by using antineutrino beams.

We study the threshold production of two pions induced by neutrinos in nucleon targets. The contribution of nucleon, pion, and contact terms are calculated using a chiral Lagrangian. The contribution of the Roper resonance, neglected in earlier studies, has also been taken into account. The numerical results for the cross sections are presented and compared with the available experimental data. It has been found that in the two-pion channels with {pi}{sup +}{pi}{sup -} and {pi}{sup 0}{pi}{sup 0} in the final state, the contribution of the N*(1440) is quite important and could be used to determine the N*(1440) electroweak transition form factors if experimental data with better statistics become available in the future.

A study of charged current induced antineutrino interactions from nuclei has been done for the intermediate energy antineutrinos and applied to {sup 12}C, relevant for ongoing experiment by MiniBooNE collaboration. The calculations have been done for the quasielastic and inelastic lepton production as well as for the incoherent and the coherent pion production processes. The calculations are done in local density approximation. In the case of the quasielastic reaction the effects of Pauli blocking, Fermi motion effects, renormalization of weak transition strengths in nuclear medium and the Coulomb distortion of the outgoing lepton have been taken into account. For the inelastic processes the calculations have been done in the {delta} dominance model and take into account the effect of Pauli blocking, Fermi motion of the nucleon, and renormalization of {delta} properties in a nuclear medium. The effect of final state interactions of pions is also taken into account. The numerical results for the total cross sections for the charged current quasielastic scattering and incoherent pion production processes are compared with earlier experimental results available in freon and freon-propane. It is found that nuclear medium effects give strong reduction in the cross sections leading to satisfactory agreement with the available data.

The normalized created-charged-particle multiplicity (R/sub 3/) in hadron-nucleus interactions has been studied as a function of the effective number of projectile encounters calculated by using the additive quark model. The analysis of the data on the ..pi../sup -/-nucleus and p-nucleus interactions obtained from emulsion and counter experiments at energies > or =50 GeV suggests a new kind of scaling whereby the R/sub 3/- relationship is projectile independent.

A study of the rapidity-gap distribution from p-N interactions obtained from an emulsion stack exposed to a 400-GeV/c proton beam at Fermilab is reported. The data show that there is a correlation in rapidity gaps such that in general a small gap ( < or = 0.1) occurs next to a small gap. This observation favors a two-channel Chew-Pignotti-type multiperipheral model. Our data also suggest that an individual cluster should consist of more than two charged particles at our energy of 400 GeV.

The $p\ensuremath{-}N$ interactions in emulsion at 67 GeV/c have been analyzed in terms of the distributions of rapidity and rapidity dispersion. The study of the dispersion parameter from individual events reveals significant clusterization amongst the final-state particles. Moreover, the nature of clusterization in the nondiffractive region of the rapidity space seems to be independent of charged-particle multiplicity of the event. This fact has been employed to estimate the mass and number of particles constituting the cluster which are found to be \ensuremath{\simeq} 2.1 GeV and \ensuremath{\simeq} 6, respectively.

A phenomenological study of the rapidity-gap distribution for cosmic-ray N-N interactions at energies> or approx. =TeV has been reported. The observations indicate strong short-short correlations in rapidity gaps which support Snider's two-channel multiperipheral cluster model. The cluster size and cluster density at these energies have been estimated to be 6.5 and 1.0, respectively. It is found that with increasing energy, the cluster size practically remains constant but the number of clusters produced per collision rises slowly.

The experimental maximum-rapidity-gap distributions in 50-GeV ${\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{-}N$ and 67- and 400-GeV $p\ensuremath{-}N$ interactions have been examined in the light of the model of Jones and Snider. The number of events due to diffractive dissociation (Pomeron exchange) at 67 GeV is estimated to be 9% and with increasing shower-particle multiplicity (${n}_{s}$), the number of such events appears to fall sharply.

The distributions of rapidity intervals for NN interactions at > or approx. =1000 GeV are analyzed within the framework of a method proposed by Adamovich et al. The data give evidence for the production of heavy clusters consisting of about eight charged particles.

New data from 400-GeV p-nucleus interactions are analyzed to investigate the variation of normalized created-charged-particle multiplicity (R/sub 3/) as a function of effective number of projectile encounters ( ) calculated by using the additive quark model. The data, combined with other available data from p-nucleus and ..pi../sup -/-nucleus reactions, confirm the projectile independence of the R/sub 3/- relationship, first observed by Kumar et al.

The vector polarization of the recoil deuteron in the elastic scattering of electrons on deuterons is calculated in the presence of weak-neutral-current couplings and is shown to be as large as other parity-violating effects in electron-nucleon scattering. Attempts should be made to detect experimentally this polarization which lies in the reaction plane.