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Journal of Physics
Published by the Institute of Physics in Association with the American Institute of Physics
Journal of Physics

Published by the Institute of Physics in Association with the American Institute of Physics

0954-3899

Journal of Physics/Journal Journal of Physics
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    Inference on fission timescale from neutron multiplicity measurement in O-18+W-184

    Rai, N. K.Gandhi, A.Kannan, M. T. SenthilRoy, S. K....
    11页
    查看更多>>摘要：The pre-scission and post-scission neutron multiplicities are measured for the O-18 + W-184 reaction in the excitation energy range of 67.23-76.37 MeV. Langevin dynamical calculations are performed to infer the energy dependence of fission decay time in compliance with the measured neutron multiplicities. Different models for nuclear dissipation are employed for this purpose. Fission process is usually expected to be faster at a higher beam energy. However, we found an enhancement in the average fission time as the incident beam energy increases. It happens because a higher excitation energy helps more neutrons to evaporate that eventually stabilizes the system against fission. The competition between fission and neutron evaporation delicately depends on the available excitation energy and it is explained here with the help of the partial fission yields contributed by the different isotopes of the primary compound nucleus.
      原文链接:
    • NSTL

    A modular A (4) symmetric scotogenic model for neutrino mass and dark matter

    Behera, Mitesh KumarSingirala, ShivaramakrishnaMishra, SubhasmitaMohanta, Rukmani...
    27页
    查看更多>>摘要：Modular symmetries have been impeccable in the neutrino and quark sectors. This motivated us to propose a variant of the scotogenic model based on modular A (4) symmetry and realize the neutrino mass generation at the one-loop level through a radiative mechanism. Alongside, we discuss the lepton flavour violating processes mu -> e gamma, mu -> 3e and mu-e conversion in the nucleus. The lightest Dirac fermion turns out to be a potential dark matter candidate, made stable by the suitable assignment of modular weights. The relic density of this has been computed with annihilations mediated by inert scalars and the new U(1) gauge boson. The LEP-II and ATLAS dilepton constraints on the new gauge parameters are suitably considered to show the consistent parameter region.
      原文链接:
    • NSTL

    Role of inelastic couplings in He-4+Pb-208 elastic scattering in a wide energy range

    Chamon, L. C.Gasques, L. R.Zamora, J. C.
    32页
    查看更多>>摘要：The phenomenological strengths of the real part of the optical potential, obtained from elastic scattering data analyses within the optical model (OM) approach, present significant energy-dependence. This behavior has been associated with the intrinsic energy-dependence of the effective nucleon-nucleon interaction. However, in earlier works, we proposed that at least part of this dependence can arise from the effect of couplings to inelastic states of the nuclei. In order to deepen this study, in this paper we present extensive data analyses for the elastic scattering and inelastic excitation of 111 states of Pb-208, for the He-4 + Pb-208 system in a wide energy range. For the purpose of comparison, the theoretical cross sections are obtained using different approaches for the imaginary part of the potential, and within both contexts: OM (distorted wave Born approximation) and coupled-channel calculations.
      原文链接:
    • NSTL

    Compton-like dark photon production in electron-nucleus collisions

    Machado, M. V. T.Hadjimichef, D.Oliveira, C. P.
    13页
    查看更多>>摘要：The Compton-like production of massive dark photons is investigated in ultrarelativistic electron-ion collisions by considering the kinetic mixing between the dark photon and the standard model photon. The quasi-real photons in the heavy ion are described by the equivalent photon approximation, and the model is employed to calculate the integrated cross section and event rates as a function of the dark photon mass, m ( gamma '), and mixing parameter, e. Predictions are shown for electron-ion colliders (EICs) in the mass range 100 <= m ( gamma ') <= 500 MeV. Numerical results are provided within the kinematic coverage of the planned machines: an EIC in China (EicC), a polarized EIC at Jefferson Lab (JLEIC), an EIC/USA (EIC), a large hadron electron collider (LHeC) and a future circular collider (FCC-eA). It complements existing search strategies for dark photons in the considered mass interval.
      原文链接:
    • NSTL

    Testing the superposition model in small CORSIKA shower simulations

    Wibig, Tadeusz
    15页
    查看更多>>摘要：The idea of superposition in the high-energy interactions of cosmic ray nuclei and the development of extensive air showers initiated by them has been known for more than half a century. It has been thoroughly and successfully tested in a number of simulations for primary energies around 10(15) and above. In this work, we will investigate its applicability to lower energies. At the lowest energies, when the shower contains on average about one charged particle (or even less), deviations from the superposition model can be seen in the simulation results. Fluctuations of higher moments of the main shower parameters are systematically broader than expected. Further studies to confirm superposition in particular in the shower longitudinal profile are in progress. A correct description of the longitudinal development of the small shower, a precise description of its fluctuations on the observational level with a correct implementation of the superposition principle will enable to construct a simple and fast phenomenological algorithm generating small showers indispensable for the interpretation of measurements made using a small local shower array and determination of the flux of single, incoherent, secondary cosmic ray particles.
      原文链接:
    • NSTL

    Soft gluon fields and anomalous magnetic moment of muon

    Nedelko, SergeiNikolskii, AlekseiVoronin, Vladimir
    19页
    查看更多>>摘要：An impact of nonperturbatively treated soft gluon modes on the value of anomalous magnetic moment of muon a ( mu ) is studied within the mean-field approach to QCD vacuum and hadronization. It is shown that radial excitations of vector mesons strongly enhance contribution of hadronic vacuum polarization to a ( mu ), doubling the contribution of one-meson processes compared to the result for ground state mesons. The mean field also strongly influences the hadronic light-by-light scattering contribution due to the Wilson line in quark propagators.
      原文链接:
    • NSTL

    Gluon EMC effects in nuclear matter

    Wang, X. G.Bentz, W.Cloet, I. C.Thomas, A. W....
    10页
    查看更多>>摘要：We investigate the gluonic structure of nuclei within a mean-field model of nuclear structure based upon the modification of the structure of a bound nucleon, with the nucleon described by the Nambu-Jona-Lasinio model. This approach has been shown to reproduce the European Muon Collaboration (EMC) effect, involving the ratio of the spin-independent structure functions of a heavier nucleus to that of the deuteron. It also predicts a significant nuclear modification for the spin structure functions, known as the polarized EMC effect. Here we report sizeable nuclear modifications of the gluon distributions (a 'gluon EMC effect') for the ratios of both the unpolarized and polarized gluon distributions in nuclear matter to those of a free nucleon.
      原文链接:
    • NSTL

    Extended study on the application of the sextic potential in the frame of X(3)-sextic

    Oulne, M.Tagdamte, I
    27页
    查看更多>>摘要：The main aim of the present paper is to extensively study the gamma-rigid Bohr Hamiltonian with anharmonic sextic oscillator potential for the variable beta and gamma = 0. For the corresponding spectral problem, a finite number of eigenvalues are explicitly found, by algebraic means, the so-called quasi-exact solvability (QES). The evolution of the spectral and electromagnetic properties by considering higher exact solvability orders is investigated, especially the approximate degeneracy of the ground and first two beta bands at the critical point of the shape phase transition from a harmonic to an anharmonic prolate beta-soft, as well as the shape evolution within an isotopic chain. The numerical results are given for 39 nuclei, namely, Ru98-108, Mo100-102, Xe116-130, Pt180-196, Os-172, Nd146-150, Ce132-134, Gd152-154, Dy154-156, Sm150-152, Hg-190 and Ra-222. Across this study, it seems that the higher QES order improves our results by decreasing the root mean square, mostly for deformed nuclei. The nuclei Ru-100,Ru-104, Xe-118,Xe-120,Xe-126,Xe-128, Nd-148 and Os-172 fall exactly at the critical point.
      原文链接:
    • NSTL