The coherent pion production induced by neutrinos in nuclei is studied using a delta hole model in local density approximation taking into account the renormalization of ∆ properties in a nuclear medium. The pion absorption effects have been included in an eikonal approximation. These effects give a large reduction in the total cross section. The numerical results for the total cross section are found to be consistent with recent experimental results from K2K and MiniBooNE collaborations and other older experiments in the intermediate energy region.PACS numbers: 13.15.+g, 23.40.Bw, 25.30.Pt The present experiments at K2K and MiniBooNE are designed to search for ν-oscillations in ν µ disappearance and ν e appearance channels. In these experiments, the ν µ -spectrum is determined by the observed energy spectrum of muons which are predominantly produced in forward direction through the charged current quasielastic reactions induced by ν µ . In this kinematic region the major background to these events come from the non quasielastic events in which pions are produced through coherent and incoherent processes induced by charged and neutral weak currents in ν-nucleus interactions. The neutral current induced π 0 production is of particular importance as it constitutes a major background to the electron signal in ν e appearance channel. The analysis of ν-oscillation experiments, therefore, requires a better understanding of pion production processes in ν-nucleus interaction and many experiments are being done to study ν-induced coherent and incoherent production of pions from nuclei [1].The coherent production of charged pions from 12 C has been recently studied by the K2K collaboration [2]. The coherent production of neutral pions has been studied by the K2K collaboration for 16 O [3] and by the MiniBooNE collaboration for 12 C [4]. Many experimental groups have earlier studied the coherent production of pions induced by neutrinos from other nuclei at higher energies [5]- [7]. Theoretically various authors [8]-[9] have used Adler's PCAC theorem to predict the total cross sections for neutrino reactions, which overestimate the experimental cross sections at low energies. In these calculations the nuclear medium effects are included only through the final state interaction of the outgoing pions with the nucleus using a model of pion nucleus scattering. A theoretical framework for treating the nuclear medium effects in the neutrino production of coherent pions using some model of nuclear structure has been recently discussed by some groups [10] but no definite predictions are made for the kinematics of the neutrino oscillation experiments of present interest.We present in this letter a calculation of the neutrino induced production of coherent pions from nuclei at intermediate neutrino energies. The nuclear medium effects are taken into account in the weak production process as well as in the final state interaction of the outgoing pions with the nucleus. The calculation uses the local density approximation to the de...

The properties of a neutron star are studied in the presence of dark matter. We have considered a relatively light weakly interacting massive particle (WIMP) as a dark matter candidate with properties suggested by the results of the DAMA/LIBRA collaboration, realized for instance within the framework of the Next-to-Minimal Supersymmetric Standard Model. The dark matter particle interacts with the baryonic matter of a neutron star through Higgs bosons. The dark matter variables are essentially fixed using the results of the DAMA/LIBRA experiment, which are then used to build the Lagrangian density for the WIMP–nucleon interaction inside a neutron star. We have used the effective field theory motivated relativistic mean field model to study the equations-of-state in the presence of dark matter. The predicted equations-of-state are used in the Tolman–Oppenheimer–Volkoff equations to obtain the mass–radius relations, the moment of inertia, and effects of the tidal field on a neutron star. The calculated properties are compared with the corresponding data of the GW170817 event.

The charged current lepton production induced by neutrinos in 56 F e nuclei has been studied. The calculations have been done for the quasielastic as well as the inelastic reactions assuming ∆ dominance and take into account the effect of Pauli blocking, Fermi motion and the renormalization of weak transition strengths in the nuclear medium. The quasielastic production cross section for lepton production are found to be strongly reduced due to nuclear effects while there is about 10% reduction in the inelastic cross sections in the absence of the final state interactions of the pions. The numerical results for the momentum and angular distributions of the leptons averaged over the various atmospheric neutrino spectra at the Soudan and Gransasso sites have been presented. The effect of nuclear model dependence and the atmospheric flux dependence on the relative yield of µ to e has been studied and discussed.PACS numbers: 25.30Pt neutrino scattering -13.15.+g Neutrino interactions -23.40.Bw Weak-interaction and lepton (including neutrino) aspects -21.60.Jz Hartee-Fock and random-phase approximations

No abstract

No abstract