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AbstractAbstract

[en] Effects of the wobbling motion on the signature splitting in triaxial odd-A nuclei are studied analytically and numerically by means of the quasiparticle-vibration coupling model that is an extension of the cranking model. The signature inversion in negative-gamma three-quasiparticle bands is shown to be driven by the rotational K mixing in the wobbling mode

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[en] We examine the effect of the spatial correlation between the valence neutrons in

^{11}Li on the cross section for (^{11}Li,^{9}Li) reactions on different targets at 800 MeV/nucleon. The correlation suppresses the nuclear part of the cross section slightly but it strongly enhances the Coulomb part compared to an independent particle description. Agreement with measurement is significantly improvedPrimary Subject

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[en] We developed the MIT bag crystal model for nuclear matter in two aspects. First, we proved a Δμ=4 selection rule in the harmonic expansion of quark wave function by group theory. It enables us to push the maximum Dirac quantum number κ

_{m}up from 7 to 15, therefore improving our calculation for the energy band and wave functions of quarks. Then, by a multipole expansion of the color fields we calculate the color interaction energy between quarks. These developments enable us to calculate the energy per nucleon in nuclear matter as done previously for a free nucleon. A nuclear equation of state is derivedPrimary Subject

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COMPOSITE MODELS, CONSTRUCTIVE FIELD THEORY, DIFFERENTIAL EQUATIONS, ELEMENTARY PARTICLES, EQUATIONS, EXTENDED PARTICLE MODEL, FERMIONS, FIELD EQUATIONS, FIELD THEORIES, FUNCTIONS, MATHEMATICAL MODELS, MATTER, PARTIAL DIFFERENTIAL EQUATIONS, PARTICLE MODELS, POSTULATED PARTICLES, QUANTUM FIELD THEORY, QUARK MODEL, WAVE EQUATIONS

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AbstractAbstract

[en] A comparison is made of the recent β

^{+}-decay measurements of Garcia et al. and the 1981^{37}Cl(p,n)^{37}Ar measurements of Rapaport et al. in order to see whether the experiments are consistent. Garcia et al. were not able to determine the amount of Gamow-Teller strength in the isobaric analog state (IAS) or the Coulomb mixing of Fermi strength to a state near the IAS, and were forced to determine the amount of Gamow-Teller strength in the daughter 1371 keV state by making the branching ratios sum to unity. This approach leaves a range of possible values open for these quantities which we investigate. We find that the experiments could be consistent within a theoretically unlikely part of this range. We also examine the effect of this range of allowed values on solar and supernova neutrino cross sections of^{37}Cl and find weak dependence on the uncertainties described here. We discuss how the consistency of the two experiments can be tested more conclusivelyPrimary Subject

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Numerical Data

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ARGON ISOTOPES, BARYON REACTIONS, BARYONS, BETA DECAY RADIOISOTOPES, BETA-PLUS DECAY RADIOISOTOPES, CALCIUM ISOTOPES, DATA, DAYS LIVING RADIOISOTOPES, DECAY, ELECTRON CAPTURE RADIOISOTOPES, ELEMENTARY PARTICLES, ENERGY RANGE, EVALUATION, EVEN-ODD NUCLEI, FERMIONS, HADRON REACTIONS, HADRONS, INFORMATION, ISOTOPES, LIGHT NUCLEI, NUCLEAR DECAY, NUCLEAR REACTIONS, NUCLEI, NUCLEON REACTIONS, NUCLEONS, NUMERICAL DATA, RADIOISOTOPES, RESONANCE, TARGETS

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[en] We investigate the electric multipole response of

^{11}Li which could be tested in reactions with secondary beams at intermediate and high energies. We use simple arguments to show that, even in the most favorable cases, electric dipole excitations are by far more dominant. The contributions from higher order multipolarities will be less than the presently attainable experimental uncertaintiesPrimary Subject

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[en] A simple derivation is given of the nonrelativistic Ward-Takahashi identity, which has been used in nearly every derivation of low-energy theorems for electromagnetic processes in nuclei. The low-energy theorem for Compton scattering is derived without assuming that identity. It is shown that gauge invariance alone leads to the correct form for the Compton amplitude, except that the magnetic recoil term does not have its conventional form. Use of Siegert's theorem, however, leads to that form

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[en] Observables in two-body reactions such as cross sections, polarizations, and spin correlations are often of simple form at threshold, since only a few partial waves contribute. Spin observables near threshold for meson photoproduction reactions (with emphasis on the γp→K

^{+}Λ case) are studied in this paper. The expected nodal structure of all sixteen observables near threshold, their evolution with momentum, the role of the centrifugal barrier on threshold multipole amplitudes, and the role of resonance effects on spin observables are discussedPrimary Subject

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Koetke, D.D.; Fisk, R.; Koetke, D.S.; Manweiler, R.; Bowles, T.J.; Brown, A.; Brown, R.E.; Burman, R.L.; Clark, D.A.; Clearwater, S.; Dombeck, T.; Kruse, H.; Lee, D.; Aas, B.; Igo, G.; Newsom, C.; Beavis, D.; Fung, S.Y.; Gorn, W.; Poe, R.T.; VanDalen, G.J.; Bassalleck, B.; Dieterle, B.; Gregory, C.; Hill, R.E.; Kang, J.H.; Leavitt, C.; Auerbach, L.; Datta, S.; Huang, Y.

AbstractAbstract

[en] A measurement of the muon-neutrino carbon charged-current cross section,

^{12}C(ν_{μ},μ^{-})X, was performed using the in-flight pion-decay neutrino source at the LAMPF accelerator. At an average interacting neutrino energy of 202 MeV an inclusive cross section of (15.9±2.6±3.7)x10^{-39}cm^{2}was measured. This value is in best agreement with the Fermi-gas model and is in disagreement with a previous experiment and subsequent calculations that yielded substantially lower cross sections. However, the muon energy spectrum shows a marked depletion of events at high energies compared to the Fermi-gas model. From a small sample of events in which the final-state nucleus was in the ground state of^{12}N, a cross section for the reaction^{12}C(ν_{μ},μ^{-})^{12}N(g.s.) of (1.7±0.8±0.3)x10^{-39}cm^{2}or about 11±5 % of the total event rate was obtainedPrimary Subject

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[en] A nonlocal optical model is used to analyze the scattering of neutrons by

^{12}C,^{16}O,^{28}Si,^{32}S, and^{40}Ca in the energy region from about 13 to 40 MeV. The real part of the internuclear interaction is obtained by using the prescription of a recently proposed nucleon + nucleus model K, which is a microscopic model based on the resonating-group formulation. A simple approximation, called the spherical approximation, is introduced to treat the cases involving non-closed-subshell target nuclei. The imaginary part used is purely phenomenological, and is obtained by simply adopting the imaginary potentials which have been found previously by other authors in their analyses with the usual local optical model. The influence of the Perey effect is taken into account by the introduction of an additional multiplicative factor. The results obtained for the differential scattering cross sections and the analyzing powers are quite satisfactory. The essential characteristics of the measured angular distributions are well reproduced. This suggests that model K is a viable model of great simplicity and can be employed to make systematic and large-scale analyses of all existing nucleon + nucleus scattering dataPrimary Subject

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[en] We extend the theory of particle-induced precompound reactions by including gamma decay. We use the Brink-Axel hypothesis and consider the gamma emission of giant-dipole resonances built on the ground state and on the excited states of the composite system. The latter are modeled as multiparticle multihole excitations. In this way, we combine the statistical ansatz and the chaining hypothesis typical for precompound reaction theories, with the collective aspects of gamma decay. Formulas for average S matrix and average cross section are derived in this framework

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