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We examined the shape staggering of relative charge radii in 180−186Hg isotopes, which was first measured in 1977 and recently confirmed using advanced spectroscopy techniques. To understand the nuclear structure underlying this phenomenon, we employed the deformed relativistic Hartree–Bogoliubov theory in continuum (DRHBc). Our analysis revealed that the shape staggering can be attributed to nuclear shape transition in the Hg isotopes. Specifically, we demonstrated that prolate shapes of 181,183,185Hg lead to an increase in the charge radii compared to oblate shapes of 180,182,184,186Hg isotopes. We explained the nuclear shape staggering in terms of the evolution of occupation probability (OP) of ν1i13/2, ν1h9/2, π1h9/2, and π3s1/2 states. Additionally, we clarified the kink structure of the charge radii in the Hg isotopes near N=126 magic shell does not come from the change of the OP of π1h9/2 state, but mainly by the increase of the OPs of ν1i11/2 and ν2g9/2 states.

We construct new effective interactions using the relativistic mean-field models with the isoscalar- and isovector-meson mixing, σ2δ2 and ωμωμρνρν. Taking into account the particle flow data in heavy-ion collisions, the observed mass of PSR J0740+6620, and the tidal deformability of a neutron star from the binary merger event, GW170817, we study the ground-state properties of finite, closed-shell nuclei, and try to explain the recent results from the PREX-2 and CREX experiments. It is found that the σ–δ mixing is very powerful to understand the terrestrial experiments and astrophysical observations of neutron stars self-consistently. We can predict the large neutron skin thickness of 208Pb, Rskin208=0.243 fm, using the slope parameter of nuclear symmetry energy, L=70 MeV, which is consistent with the PREX-2 result. However, to explain the CREX data, it is preferable to adopt the small value of L=20 MeV. It is very difficult to understand the PREX-2 and CREX results simultaneously within relativistic mean-field models.

It is thought that photon vortices are predominantly produced in extremely strong magnetic fields in the Universe. Because the photon vortex may cause significant large angular momentum transfer in interactions with atomic nuclei, stellar nucleosynthesis in such astrophysical environments is affected. In the present study, we calculate the ratios of the photon absorption transition probabilities of photon vortices with Bessel wave to photons described by the plane wave. The result shows enhancement of excitation of states with large total angular momentum by optimization of the divergence angle of the incident photon vortex in momentum space. However, the average cross section for the photon vortex turns out to be identical with that for the plane wave. Therefore, even when Bessel photons are predominantly produced in astrophysical environments, the isotopic abundances of the synthesized elements are not changed.

We formulate a theoretical approach to describe photon vortex production in synchrotron/cyclotron radiation from a helical moving electron under a uniform magnetic field in the relativistic quantum framework. In quantum theory, electron orbitals in a magnetic field are under Landau states. The Landau level density increases with decreasing the magnetic field strength, and it is practically impossible to calculate exactly the synchrotron radiation in possible magnetic fields in the laboratory. We present a method to calculate it by using asymptotic formulations of the emission amplitudes under the condition of L_{i}−L_{f}≪L_{i}, where L_{i} and L_{f} are the initial and final Landau numbers, respectively. The wave function of the generated photon is the eigenstate of the z component of the total angular momentum (zTAM) when the magnetic field is parallel to the z axis. The approximation is applicable for photon vortex production of several tens ℏ of zTAM. We also calculate numerically the energy spectra and spatial distribution of photon vortices in magnetic field strengths of 10 and 20 T using electrons with energies of 150 MeV and 8 GeV and Larmor radii of 10 and 100 µm for the helical motion. Although the Landau number becomes up to 10^{8} in these conditions, the radiations could be calculated using the approximation. The results indicate that it is possible to produce predominantly photon vortices with a fixed zTAM when we control the energy and entrance trajectory of electrons and the structure of a magnetic field. The present formula contributes to the prediction and verification of photon vortex generation.

We report that the standard evolution of radiation-dominated era (RDE) universe a∝t1/2 is a sufficient condition for solving a sixth order gravitational field equation derived from the Lagrangian containing BRabRab+CRR;cc as well as a polynomial f(R) for a spatially flat radiation FLRW universe. By virtue of the similarity between RabRab and R2 models up to the background order and of the vanishing property of R;cc for H=1/(2t), the analytical solution can be obtained from a special case to general one. This proves that the standard cosmic evolution is valid even within modified gravitational theory involving higher-order terms. An application of this background solution to the tensor-type perturbation reduces the complicated equation to the standard second order equation of gravitational wave. We discuss the possible ways to discriminate the modified gravity model on the observations such as the gravitational wave from the disturbed universe and primordial abundances.

We explore photon vortex generation in synchrotron radiations from a spiral moving electron under a uniform magnetic field along z-axis using Landau quantization. The obtained wave-function of the photon vortices is the eigen-state of the z-component of the total angular momentum (zTAM). In m-th harmonic radiations, individual photons are the eigen-state of zTAM of mħ. This is consistent with previous studies. Using the presently obtained wave-functions we calculate the decay widths and the energy spectra under extremely strong magnetic fields of 1012–1013 G, which are observed in astrophysical objects such as magnetized neutron stars and jets and accretion disks around black holes. The result suggests that photon vortices are predominantly generated in such objects. Although they have no coherency it is expected that photon vortices from the universe are measured using a detector based upon a quantum effect in future. This effect also affects to stellar nucleosynthesis in strong magnetic fields.

We study neutrino and antineutrino emission from the direct Urca process in neutron-star matter in the presence of strong magnetic fields. We calculate the neutrino emissivity of the direct Urca process, whereby a neutron converts to a proton, an electron and an antineutrino, or a proton-electron pair converts to a neutron-neutrino pair. We solve exact wave functions for protons and electrons in the states described with Landau levels. We find that the direct Urca process can satisfy the kinematic constraints even in density regions where this process could not normally occur in the absence of a magnetic field.

We present a modified Gamow factor by reinvestigating the conventional assumptions used in its derivation. The conventional Gamow factor, factorized from the total cross section, effectively describes the penetration probabilities (PPs) in low-energy nuclear reactions under the assumption of particle energies significantly lower than the Coulomb barrier. However, we find that the assumption is invalid for light nuclei, resulting in PPs that depend on the nuclear potential depth for such nuclei. By adopting a potential depth fitted to experimental fusion cross sections, we demonstrate that PPs for light nuclei (D+D, D+T, D+ ^3 He, p+D, p+ ^6 Li, and p+ ^7 Li) become higher than those predicted by the conventional form near the Coulomb barrier. This reduces the Gamow peak energy by a factor of 5.3 maximally compared to the conventional form. Furthermore, we show that the enhancement factor due to the Debye screening effects in the solar core can be reduced by approximately 5%–10% due to the modified PP. Our findings hold implications for evaluating the available energy region in low-energy reaction experiments based on the Gamow peak energy region and for understanding electron screening effects in typical astrophysical environments.

We study the νν¯-pair synchrotron emission from electrons and protons in a relativistic quantum approach. This process occurs only in the presence of a strong magnetic field, and it is considered to be one of effective processes for neutron star cooling. In this work we calculate the luminosity of the νν¯-pairs emitted from neutron-star-matter with a magnetic field of about 1015 G. We find that the energy loss is much larger than that of the modified Urca process. The νν¯-pair emission processes in strong magnetic fields is expected to contribute significantly to the cooling of the magnetars.

Using the Lorentz-covariant decomposition of nucleon self-energies based on the Hugenholtz–Van Hove theorem, we study the effect of Fock terms on the nuclear symmetry energy and its slope parameter within relativistic Hartree-Fock approximation. It is found that the exchange contribution suppresses the nuclear symmetry energy and prevents the slope parameter from increasing monotonically at high densities. Furthermore, not only the isovector-vector (ρ) meson but also the isoscalar mesons (σ,ω) and pion give significant influence on the potential term of nuclear symmetry energy through the exchange diagrams. Keywords: Asymmetric nuclear matter, Nuclear symmetry energy, Relativistic Hartree-Fock approximation

We discuss the role of two-neutron transfer processes in the fusion reaction of the 9,11Li + 208Pb systems. We first analyze the 9Li + 208Pb reaction by taking into account the coupling to the 7Li + 210Pb channel. To this end, we assume that two neutrons are directly transferred to a single effective channel in 210Pb and solve the coupled-channels equations with the two channels. By adjusting the coupling strength and the effective Q-value, we successfully reproduce the experimental fusion cross sections for this system. We then analyze the 11Li + 208Pb reaction in a similar manner, that is, by taking into account three effective channels with 11Li + 208Pb, 9Li + 210Pb, and 7Li + 212Pb partitions. In order to take into account the halo structure of the 11Li nucleus, we construct the potential between 11Li and 208Pb with a double folding procedure, while we employ a Woods–Saxon type potential with the global Akyüz–Winther parameters for the other channels. Our calculation indicates that the multiple two-neutron transfer process plays a crucial role in the 11Li + 208Pb fusion reaction at energies around the Coulomb barrier. Keywords: Coupled-channels method, Total fusion cross section

We utilize an exact quantum calculation to explore axion emission from electrons and protons in the presence of the strong magnetic field of magnetars. The axion is emitted via transitions between the Landau levels generated by the strong magnetic field. The luminosity of axions emitted by protons is shown to be much larger than that of electrons and becomes stronger with increasing matter density. Cooling by axion emission is shown to be much larger than neutrino cooling by the Urca processes. Consequently, axion emission in the crust may significantly contribute to the cooling of magnetars. In the high-density core, however, it may cause heating of the magnetar. Keywords: Axion production, Strong magnetic field, Quantum approach, Landau level

We investigate neutron-proton (np) pairing correlation effect on the shell evolution of ground-state energies along with the deformation for N = Z nuclei in sd- and pf-shell, such as 24Mg and 72Kr. We start from a simple shell-filling model constructed by a deformed Woods-Saxon potential characterized as β2 deformation, and then we include all kinds of pairing correlations in the residual interaction. In this work, like- and unlike-pairing correlation decomposed as isoscalar (IS) T = 0 and isovector (IV) T = 1 component are explicitly taken into account to estimate the ground-state energies. It turns out that the IS condensation can explain the oblate deformation for 72Kr. We also test those effects on the Gamow- Teller (GT) transition for another N = Z nucleus, 56Ni, which explicitly exhibits the effects by the IS condensation and the deformation. [ABSTRACT FROM AUTHOR]

We discuss effects of shock propagation on neutrino (v) oscillation in supernova environment, which affects directly v-induced nucleosynthesis. Since electron number density varies rapidly behind and in front of the shock, multiple resonances of mixing angles by adiabatic and/or nonadiabatic electron density change can occur during the shock propagation. In this work, we report detailed analysis of the v oscillation in matter and the v-induced nucleosynthesis by the shock propagation. The shock effects increase abundances by about 16% of 138La, 14% of 92Nb and 7% of 98Tc, whose main synthesized region is O-Ne-Mg layer in our supernova model. Here, we adopt a simple thermal bomb hydrodynamic model and the normal v-mass hierarchy. [ABSTRACT FROM AUTHOR]

Ground states of even-even Ge isotopes with mass number A = 64-76 have been studied in the deformed Bardeen-Cooper-Schrieffer (BCS) theory by taking neutron-proton (np) pairing correlations as well as neutron-neutron (nn) and proton-proton (pp) pairing correlations. The np pairing has two different modes J = 0, T = 1 (isotriplet) and J = 1, T = 0 (isosinglet). In this work, the Brueckner G matrix, based on the CD-Bonn potential, has been exploited to reduce the ambiguity regarding nucleon-nucleon interactions inside nuclei compared to the results by a simple schematic phenomenological force. We found that the G matrix plays important roles to obtain reasonable descriptions of even-even nuclei compared to the schematic force. The np pairing strength has been shown to have a clear correlation with quadrupole deformation parameter β2 for the isotopes, and affects the smearing of the Fermi surfaces of not only N = Z nuclei but also N ≠ Z nuclei. In particular, the coexistence of the like particle (nn and pp) and the np pairing modes was found to become more salient by the G-matrix approach than by the schematic force approach. [ABSTRACT FROM AUTHOR]

We study the effects of density-dependent weak vector form factors on the inclusive neutral-current-neutrino (antineutrino)-nucleus scattering in the quasi-elastic region within the framework of a relativistic single-particle model. The density-dependent weak form factors are obtained from a quark-meson coupling model. The density-dependence effects are studied separately in protons and neutrons participating in the reactions, in each response cross section, and with regard to asymmetry. These density effects reduce the cross section at high densities and show different behavior with regard to asymmetry. Furthermore we calculate flux-averaged differential cross sections and compare them with the experimental data. [ABSTRACT FROM AUTHOR]

Within the framework of a relativistic single particle model, we study the effects of density-dependent electromagnetic form factors on the inclusive (e,e') reaction in the quasi-elastic region. The density-dependent form factors generated by a quark-meson coupling model are applied into the (e,e') reaction. We calculate the differential cross sections, and extract the longitudinal and transverse structure functions. Furthermore the Coulomb sum is calculated in terms of three momentum transfer from 40Ca. The effects of the density-dependent form factors reduce the longitudinal structure function by amount of a few percent but increase the transverse structure function about 10%, consequently the (e,e') differential cross sections are enhanced. [ABSTRACT FROM AUTHOR]

We study the effects of density-dependent electromagnetic, axial, and weak vector form factors on the inclusive (e,e') reaction and the charged-current neutrino-nucleus scattering in the quasi-elastic region within the framework of a relativistic single-particle model. The density-dependent form factors obtained from a quark-meson coupling model are applied into the (e,e') reaction and the neutrino-nucleus scattering via charged current. The effects of the density-dependent form factors increase the (e,e') cross sections by a few percent. However, the effects may reduce the differential cross sections up to 20% (60%) at p=1.0pO(2.0pO) for the antineutrino scattering and also reduce the cross section up to 20% (30%) at p=1.0pO(2.0pO) for the neutrino scattering around the peak positions, where the normal density is p0~0.15 fm-3. For the density of finite nuclei such as 12C, 40Ca, and 208Pb as 0.6, 0.7, and 1.0 of pO, the in-medium effects are 20% to 30%, even in the antineutrino case. Our theoretical double-differential and total cross sections are compared with the recent MiniBooNE data for 12C(µ,µ-) scattering. [ABSTRACT FROM AUTHOR]

We investigate the effect of final state interaction (FSI) on the neutrino (antineutrino) scattering via neutral current from a 12C target in the quasielastic region within the framework of a relativistic single-particle model. Three different descriptions of the FSI, which are a relativistic mean field, a complex optical potential, and its real potential, are taken into account for two incident neutrino energies of 500 MeV and 1 GeV. The effects of the FSI are studied not only on the differential cross sections but also on each longitudinal, transverse, and transverse interference cross section. We found that the FSI description may play a vital role for the estimation of those cross sections, and the FSI effects on each response cross section may differ from those on the differential cross section. However, the asymmetry between neutrino and antineutrino scattering cross sections turns out to be nearly independent of the FSI descriptions. Finally, possible FSI effects on the MiniBooNE data are studied in detail. [ABSTRACT FROM AUTHOR]

Gamow-Teller (GT) strength distributions of Mg isotopes are investigated within a framework of the deformed quasiparticle random-phase approximation. We found that the N = 20 shell closure in 28~34Mg was broken by the prolate shape deformation originating from the fp-intruder states. The shell closure breaking gives rise to a shift of low-lying GT excited states into high-lying states. Discussions regarding the shell evolution trend of single-particle states around N = 20 nuclei are also presented with the comparison to other approaches. [ABSTRACT FROM AUTHOR]

Using several relativistic mean-field models (such as GM1, GM3, NL3, TM1, FSUGold, and IU-FSU) as well as the quark-meson coupling model, we calculate the particle fractions, the equation of state, the maximum mass, and radius of a neutron star within relativistic Hartree approximation. We also discuss in detail the role of nonlinear potentials involved in the mean-field models. In determining the couplings of the isoscalar, vector mesons to the octet baryons, we examine the extension of SU(6) spin-flavor symmetry to SU(3) flavor symmetry. Furthermore, we consider the strange (σ* and Φ) mesons and study how they affect the equation of state. We find that the equation of state in SU(3) symmetry can sustain a neutron star with mass of (1.8 ~ 2.1 )M⊙, even if hyperons exist inside the core. It is noticeable that the strange vector (Φ) meson and the variation of baryon substructure in matter also play important roles in supporting a massive neutron star. [ABSTRACT FROM AUTHOR]

The nucleón form factors in free space are usually thought to be modified when a nucleón is bound in a nucleus or immersed in a nuclear medium. We investigate effects of the density-dependent axial and weak-vector form factors on the electroneutrino (ve) and anti-electroneutrino (ve) reactions with incident energy Ev ≤ 80 MeV via neutral current (NC) for a nucleón in a nuclear medium or 12C. For the density-dependent form factors, we exploit the quark-meson-coupling (QMC) model, and apply them to the ve and ve induced reactions by NC. About 12% decrease of the total cross section by the ve reaction on the nucleón is obtained at normal density, ρ = ρ0 ~ 0.15 fm-3, as well as about 18% reduction of the total ve cross section on 12C, by the modification of the weak form factors of the bound nucleón. However, similarly to the charged current reaction, effects of the nucleón property change in the ve reaction reduce significantly the cross sections about 30% for the nucleón in matter and 12C cases. Such a large asymmetry in the ve cross sections is addressed to originate from the different helicities of ve and ve. [ABSTRACT FROM AUTHOR]

We study inclusive charged-current reaction through total cross sections of neutrino-nucleus scattering within the framework of a relativistic single-particle model in the quasielastic region. To describe the final-state interaction between knocked-out nucleons and the residual nucleus, a real potential of final nucleons, which is generated by a relativistic mean field, is used with the assumption of no loss of flux, which leads to current conservation and gauge invariance. We calculate (?μ,μ-) and (vμ,μ+) reactions. In these calculations, 12C, 40Ca, and 208Pb are used as target nuclei and the incident neutrino (antineutrino) energies are exploited up to 4 GeV. We find that the effect of the final-state interaction by the real potential of the knocked-out nucleons reduces cross sections by about 15%, similar to the effect of electron scattering. Furthermore, the effect of the Coulomb distortion for the outgoing leptons is shown to be different from the electron scattering. Finally, our total cross sections by scaling number of participated nucleons are presented to compare with experimental data. [ABSTRACT FROM AUTHOR]

We calculated neutrino reactions on 40Ar for detecting core-collapsing supernovae (SNe) neutrinos. The nucleus was originally exploited to identify the solar neutrino emitted from 8B produced in pp chains on the Sun. With the higher energy neutrinos emitted from the core-collapsing SNe, contributions from higher multipole transitions, as well as from the Gamow-Teller and Fermi transitions, are shown to be important ingredients for understanding reactions induced by the SN neutrino. Moreover, higher excited states beyond a few states known in experiment diminish significantly the expected large difference between the cross sections of νe and νe reactions on 40Ar, which difference is anticipated because of the large Q value in the νe reaction. The reduction is shown to lead to a difference between them of only a factor of 2. [ABSTRACT FROM AUTHOR]

The phase transition at temperature variation is washed out in the finite system. Quantum or statistical fluctuations may give rise to this situation. It is still uncertain whether these fluctuations are caused by approximation error or finiteness of the system. Here we use another approximation the functional Schrödinger picture formalism founded on the variational principle and study the few-body nucleon system by using this formalism. [ABSTRACT FROM AUTHOR]

We perform systematic calculations regarding the effects by Coulomb and/or spin-orbit (SO) interaction on like- and unlike-pairing correlations in sd-, pf-, and sdgh-shell N=Z nuclei. The former two interactions are comprised in a deformed mean-field potential and the latter pairing correlations are treated by residual interactions in the mean field. We make use of two different pairing matrix elements (PMEs) for the residual interactions : constant and state-dependent Brueckner G matrix. The constant PME may give rise to meaningful information on the pairing correlations under the Wigner spin-isospin SU(4) symmetry in the absence of the Coulomb and the SO interaction. The state-dependent Brueckner PME takes into account the nuclear medium effect based on a realistic nucleon-nucleon interaction. In this work, through the analyses of the Coulomb and the SO interaction effects on the pairing correlations, we discuss in detail the isoscalar pair condensation and the coexistence of the isoscalar and the isovector pairs in the unlike pairing of the N=Z nuclei. Our results show that the Coulomb and the SO interaction as well as nuclear deformation affect the single-particle state evolution in a deformed mean field and, as a result, give significant impacts on the pairing correlations and the smearing of occupation probabilities near Fermi energy. In particular, the pairing gaps in the heavy nuclei are largely disturbed by the Coulomb interaction as well as the SO interaction. [ABSTRACT FROM AUTHOR]

We reinvestigate effects of neutrino oscillations on the production of 7Li and 11B in core-collapse supernovae (SNe). During the propagation of neutrinos from the proto–neutron star, their flavors change, and the neutrino reaction rates for spallation of 12C and 4He are affected. In this work, corrected neutrino spallation cross sections for 4He and 12C are adopted. Initial abundances involving heavy s-nuclei and other physical conditions are derived in a new calculation of the SN 1987A progenitor in which the effects of the progenitor metallicity are included. A dependence of the SN nucleosynthesis and final yields of 7Li and 11B on the neutrino mass hierarchy are shown in several stellar locations. In the normal hierarchy case, the charged-current (CC) reaction rates of are enhanced, and yields of proton-rich nuclei, along with 7Be and 11C, are increased. In the inverted hierarchy case, the CC reaction rates of are enhanced, and yields of neutron-rich nuclei, along with 7Li and 11B, are increased. We find that variation of the metallicity modifies the yields of 7Li, 7Be, 11B, and 11C. This effect is caused by changes in the neutron abundance during SN nucleosynthesis. Therefore, accurate calculations of Li and B production in SNe should take into account the metallicity of progenitor stars. [ABSTRACT FROM AUTHOR]

We investigated neutron-proton pairing correlations effects on the shell evolution of ground-state energies by the deformation for N=Z nuclei in pf shell, such as 44Ti, 48Cr, 52Fe, 64Ge, 68Se, 72Kr, and 76Sr. We started from a simple shell-filling model constructed by a deformed Woods-Saxon potential with β2 deformation, and included pairing correlations in the residual interaction, which give rise to smearing of the Fermi surface revealing interesting evolution of the Fermi energy along the shell evolution. In this work, like-pairing and unlike-pairing correlations decomposed as isovector T=1 and isoscalar T=0 components are explicitly taken into account. Finally, we estimate ground-state energies comprising the mean-field energy, the pairing energy, and the self-energy due to the pairing correlations, in terms of the deformation. The enhanced T=0 pairing interaction supports oblate deformations for 72Kr and 68Se, whose features are different from other pf-shell N=Z nuclei considered in this work. [ABSTRACT FROM AUTHOR]

We study the shape evolution of N=Z nuclei 24Mg,28Si, and 32S in the axially symmetric deformed Woods-Saxon model, taking into account both T=0 and T=1 pairing interactions. We find the coexistence of T=0 and T=1 superfluidity phases in the large deformation region |β2|>0.3 in these three nuclei. The interplay between the two pairing interactions has an important effect on determining the deformation of the ground states in these nuclei. The self-energy contributions from the pairing correlations to the single particle (s.p.) energies are also examined. [ABSTRACT FROM AUTHOR]

A new scheme for the short baseline electron antineutrino () disappearance study is investigated. We propose to use an intense neutron emitter, 252Cf, which produces a 8Li isotope through the 7Li(n,γ)8Li reaction; 8Li is a emitter via decay. Because this source needs neither accelerator nor reactor facilities, the can be placed on any neutrino detector as closely as possible. This short baseline circumstance with a suitable detector enables us to study the existence of possible sterile neutrinos, in particular, on 1 eV mass scale. Also, complementary comparison studies among different neutrino detectors can become feasible by using from the 8Li source. As an example, applications to hemisphere and cylinder shape scintillator detectors are performed in detail with the expectation signal modification by the sterile neutrino. Sensitivities to mass and mixing angles of sterile neutrinos are also presented for comparison with those of other neutrino experiments. [ABSTRACT FROM AUTHOR]

We investigate effects of neutron-proton (np) pairing correlations on the Gamow-Teller (GT) transition of 24,26Mg by explicitly taking into account deformation effects. Our calculation is performed by a deformed quasiparticle random phase approximation (DQRPA) which includes the deformation at the Bardeen-Cooper-Schrieffer and RPA stage. In this paper, we include the np pairing as well as neutron-neutron (nn) and proton-proton (pp) paring correlations to the DQRPA. Our new formalism is applied to the GT transition of well-known deformed Mg isotopes. The np pairing effect is found to affect more or less the GT distribution of 24Mg and 26Mg. But the deformation effect turns out to be much larger than the np paring effect because the Fermi surfaces smear more widely by the deformation rather than the np pairing correlations. Correlations between the deformation and the np pairing effects and their ambiguities are also discussed with the comparison to experimental GT strength data by triton and ³He beams. [ABSTRACT FROM AUTHOR]

Production of a neutrino source through a proton-induced reaction is studied by using the particle transport code GEANT4. Unstable isotopes such as 27Si can be produced when the 27Al target is bombarded by 15-MeV energetic proton beams. Through the β-decay process of the unstable isotope, a new electron-neutrino source in the 0-5.0 MeV energy range is obtained. Proton-induced reactions are simulated with JENDL-4.0 High Energy File (JENDL-4.0/HE). For radioactive decay processes, we use the G4 radioactive decay model based on the Evaluated Nuclear Structure Data File (ENSDF). We suggest detailed target systems required for future solar neutrino experiments, in particular for the vacuum-matter transition region. As for a detection system of the new neutrino source, we evaluate reaction or event rates for available radiochemical detectors and Low Energy Neutrino Astronomy (LENA)-type scintillator detector and discuss effects due to possible sterile neutrinos as an application. [ABSTRACT FROM AUTHOR]

We construct the equation of state (EoS) for neutron stars explicitly including hyperons and quarks. Using the quark–meson coupling model with the relativistic Hartree–Fock approximation, the EoS for hadronic matter is derived by taking into account the strange (σ* and ϕ) mesons as well as the light non-strange (σ, ω, , and ) mesons. Relevant coupling constants are determined to reproduce the experimental data of nuclear matter and hypernuclei in SU(3) flavor symmetry. For quark matter, we employ the MIT bag model with a one-gluon-exchange interaction, and Gibbs criteria for chemical equilibrium in the phase transition from hadrons to quarks. We find that the strange vector (ϕ) meson and the Fock contribution make the hadronic EoS stiff, and that the maximum mass of a neutron star can be consistent with the observed mass of heavy neutron stars even if the coexistence of hadrons and quarks takes place in the core. However, in the present calculation, the transition to pure quark matter does not occur in stable neutron stars. Furthermore, the lower bound of the critical chemical potential of the quark–hadron transition at zero temperature turns out to be around 1.5 GeV in order to be consistent with the recent observed neutron-star data. [ABSTRACT FROM AUTHOR]

We investigated the in-medium effect by density-dependent axial and weak-vector form factors on muon-neutrino () and anti-muon-neutrino scattering in the quasi-elastic (QE) region from nucleons (N*) bound in a nucleus or immersed in a nuclear medium via neutral current (NC) and charged current (CC). For the density-dependent form factors, we exploited a quark–meson-coupling (QMC) model. We found that the scattering cross sections via NC in the QE region usually decrease with an increased medium density, while those using CC were increased. However, their rate of change was sensitive to the four-momentum transfer given to a bound nucleon through scattering. We compared these results obtained by the elementary process corrected by the in-medium effect to the BNL and MiniBooNE data, which measured scattering cross sections per nucleon through – 12C scattering in 12C composite targets. The incident energy range was 550 3000 MeV. We increased the energy up to 100 GeV to compare our results to the NOMAD experimental data. In order to study the density effects on a nucleon embedded in 12C, we exploited the QMC form factors evaluated at , where the normal density . The strangeness contributions in NC scattering are also incorporated into the form factors for comparison with experimental data. Our numerical results show that most of the experimental data can be explained in a satisfactory manner by the density-dependent elementary process, but there are some remaining deviations resulting from the nuclear structure, particularly in the low and high momentum-transfer regions. [ABSTRACT FROM AUTHOR]

Using an optical model potential including an inelastic scattering potential as well as a conventional short-range nuclear potential, we investigate the ratio Pinel of the inelastic scattering cross section to the Rutherford cross section for the 11Be + 197Au system. As a result, we find that the contribution of the inelastic scattering to the first excited state of the 11Be projectile cannot be ignored at backward angles in unresolved elastic + inelastic scattering data and the Pinel relevant to the contribution of inelastic scattering depends on the incident energy Ec.m. and excitation energy ε. [ABSTRACT FROM AUTHOR]

We study the effects of the strange axial form factor and axial mass on both neutral- and charged-current reactions in the quasielastic region within the framework of a relativistic single-particle model. For this purpose, we calculate the differential cross section, the separated cross sections associated with the longitudinal and transverse response functions, the asymmetry for the neutral-current reaction, and the various ratios of the neutral- to charged-current reactions. The calculations are performed for a 12C target at specific incident neutrino (antineutrino) energies of 0.5 and 1.5 GeV, or with the flux-averaged incident energies of the MiniBooNE experiment. Then, we discuss the dependence of the cross sections, asymmetry, and ratios on the axial mass and strange axial form factor. Finally, we compare our calculations with the MiniBooNE experimental data. [ABSTRACT FROM AUTHOR]

For the 11Li + 208Pb system, we find that the breakup process takes place from the forward angle or far distance region through the interaction distance which is obtained from ratios of elastic scattering cross sections to the Rutherford cross section. It is well known that the behavior of the 11Li + Pb208 system is closely related to Coulomb dipole excitation effect. From the first Χ² analysis for the elastic cross section of the 9Li + 208Pb system, we obtain the short-range potential of the 11Li + 208Pb system by exploiting the optical model calculation for the Coulomb dipole excitation effect. To include the effect of the long-range interaction, we use a dynamic complex polarization potential including the Coulomb dipole potential and a long-range nuclear potential with Woods-Saxon form. Using the second Χ² analysis for the elastic cross section of the 11Li+ 208Pb system, we obtain the electric dipole transition probabilities B(E1) which becomes 1.42 e²fm² and 1.41 e²fm² at Ec.m. = 23.1 MeV and 28.3 MeV, respectively. [ABSTRACT FROM AUTHOR]

We have studied the large-scale dynamo forced with helical magnetic energy. Compared to the kinetic forcing process, the magnetic process is not clearly observed nor intuitive. However, it may represent the actual B field amplification in the stellar corona, accretion disk, plasma lab, or other magnetically dominated systems where the strong kinetic effect does not exist. The interaction between the magnetic field and the plasma is essentially nonlinear. However, when the plasma system is driven by helical energy, whether kinetic or magnetic, the nonlinear process can be linearized with pseudotensors a , β and the large-scale magnetic field $\overline{{\boldsymbol{B}}}$ . Conventionally, the α effect is thought to be the main dynamo effect converting kinetic energy into magnetic energy and transferring it to the large-scale regime. In contrast, β effect has been thought to diffuse magnetic energy. However, these conclusions are not based on the exact definition of α and β . In this paper, instead of the analytic definition of α and β , we derive a semi-analytic equation and apply it to the simulation data. The half analytic and numerical result shows that the averaged α effect is not so important in amplifying the $\overline{{\boldsymbol{B}}}$ field. Rather, it is the negative β effect combined with the Laplacian (∇ ^2 → − k ^2 ) that plays a key role in the dynamo process. Further, the negative magnetic diffusivity accounts for the attenuation of the plasma kinetic energy ${\overline{E}}_{V}$ in large scales. We discuss this process using the theoretical method and the intuitive field structure model.

The roles of strange axial form factor and axial mass for both neutral-current and charged-current reactions are investigated in the quasi-elastic neutrino-nucleus scattering within a relativistic single-particle model. The calculation is performed for various target nuclei like 12C, 40Ca, 56Fe, and 208Pb at the incident neutrino (antineutrino) energies of 1.0 and 2.0 GeV. Then we discuss the dependence of differential cross section on the role of axial mass and strange axial form factor with different target nuclei on both neutral-current and charged-current reactions. Finally we compare our results with the MiniBooNE, T2K, and MINERνA experimental data for the double-differential cross section and the scaled total cross section. [ABSTRACT FROM AUTHOR]

The isotope 98Tc decays to 98Ru with a half-life of 4.2×106 yr and could have been present in the early Solar System. In this Letter, we report on the first calculations of the production of 98Tc by neutrino-induced reactions in core-collapse supernovae (the ν process). Our predicted 98Tc abundance at the time of solar system formation is not much lower than the current measured upper limit raising the possibility for its detection in the not too distant future. We show that, if the initial abundance were to be precisely measured, the 98Tc nuclear cosmochronometer could be used to evaluate a much more precise value of the duration time from the last core-collapse supernova to the formation of the solar system. Moreover, a unique and novel feature of the 98Tc ν-process nucleosynthesis is the large contribution (~20%) from charged current reactions with electron antineutrinos. This means that 98Tc becomes a unique new ν-process probe of the temperature of the electron antineutrinos. [ABSTRACT FROM AUTHOR]

We investigated effects of pairing correlations on the neutron skin thickness and the symmetry energy of finite nuclei. In this calculation we used Hartree-Fock-Bogoliubov method with Skyrme forces and effective pairing interactions. The results have been compared with available experimental data, Hartree-Fock results as well as the predictions by droplet model. Finally, our discussion was extended to study of the pairing interaction in nuclear matter. Roles of isospin T = 0 pairing in the nuclear matter were also discussed. [ABSTRACT FROM AUTHOR]

Within the framework of a relativistic single-particle model, we calculate inclusive electron-nucleus scattering by electromagnetic current, and neutrino-nucleus scattering by neutral and charged current in the quasi-elastic region. The longitudinal, the transverse, and the transverse-interference structure functions are extracted from the theoretical cross section by using the Rosenbluth separation method at fixed momentum transfer and scattering angle and then compared with each other from the viewpoint of these current interactions. The position of peak for the electron scattering shifts to higher energy transfer than that for the neutrino scattering. The axial and pseudoscalar terms turn out to play an important role in the neutrino-nucleus scattering. [ABSTRACT FROM AUTHOR]

We investigate ratios of the elastic scattering cross section to Rutherford cross section, PE, and angular distributions of breakup cross section by using an optical model which exploits various long-range dynamic polarization potentials as well as short-range nuclear bare potentials for the 11Be projectile. From these simultaneous analyses, we extract a large radius of a halo projectile from the experimental data for PE and the angular distribution of the breakup cross section of the 11Be+64Zn and 11Be+120Sn systems. It results from the fact that a large radius for the long-range nuclear potential is more reasonable for properly explaining these data simultaneously. The extracted reduced interaction radius turns out to be r0=3.18~3.61 fm for 11Be nucleus, which is larger than the conventional value of r0=1.1~1.5 fm used in the standard radius form R=r0A1/3. Furthermore, the larger radius as well as the normalization constant N is shown to be important for understanding Coulomb dipole strength distribution. [ABSTRACT FROM AUTHOR]

both the CDE and LRN potentials are essential to explaining the experimental values of PE, which is the ratio of the elastic scattering cross section to the Rutherford cross section. The Coulomb and nuclear parts of the LRDP potential are found to contribute to a strong absorption effect. Strong absorption occurs because the real part of the CDE and LRN potentials lowers the barrier, and the imaginary part of the CDE and LRN potentials removes the flux from the elastic channel in the 11Be + 64Zn system. Finally, we extract the total reaction cross section σR including the inelastic, breakup, and fusion cross sections. The contribution of the inelastic scattering by the first excited state εx = 0.32 MeV (l/2-) is found to be relatively large and cannot be ignored. In addition, our results are shown to agree quite well with the experimental breakup reaction cross section by using a fairly large radius parameter. [ABSTRACT FROM AUTHOR]

We estimate the maximum possible contribution to the early spin deceleration of protoneutron stars because of asymmetric neutrino absorption. We calculate the neutrino scattering in the context of a fully relativistic mean field theory and estimate for the first time the spin deceleration of neutron stars because of asymmetric neutrino absorption in a toroidal magnetic field configuration. We find that the deceleration can be much larger for asymmetric neutrino absorption in a toroidal magnetic field than the braking due to magnetic dipole radiation. Nevertheless, the effect is estimated to be less than the angular momentum loss due to the transport of magnetically locked material in the neutrino energized wind. [ABSTRACT FROM AUTHOR]

We investigate the structure of proto-neutron stars (PNSs) with trapped neutrinos by using a quark-meson coupling model. We adopt a phenomenological lepton density which is diffuse near the surface. We calculate the populations of baryons and leptons, the equations of state, and the mass-radius relation for isentropic PNS models. In addition, the moment of inertia is calculated for both PNS and cold-neutron-star (CNS) models as a means to study the change of the spin period due to the neutrino emission from a PNS. Neutrino emission from a hyperonic neutron star is shown to increase the spin by about 10% of the initial spin, while the spin of a nucleonic neutron star with a central density above ρc &ap; 5ρ0 is decreased by a few % by the emission of neutrinos. Therefore, the spin change owing to the leakage of neutrinos from a PNS is a small (<10%) correction compared to other processes related to the spin change [ABSTRACT FROM AUTHOR]

We investigate the structure of a proto-neutron star with trapped neutrinos by using quantum hadrodynamics. Ratios of the trapped neutrinos and corresponding leptons to the baryons are usually assumed to be constant. But relevant reactions associated with the β equilibrium could be sensitive to the given density and temperature. By adopting a phenomenological lepton density that is smeared near the surface, we calculate and discuss populations of baryons and leptons, equations of state, and the mass-radius relation of a proto-neutron star in an isentropic process. [ABSTRACT FROM AUTHOR]