123383131
Multipole Amplitudes for Pion Weak-Production near Threshold by Charged Current
We investigated pion production by charged weak current, which comprises vector and axial vector current. In particular, the contribution by the axial vector current is detailed at the pion threshold in terms of multipole amplitudes, which could be useful tools for understanding the pion weak-production by combining the multipole amplitudes deduced from other probes. By exploiting the chiral Ward identities based on the QCD Lagrangian, we derived relevant multipole amplitudes in closed forms and showed their numerical results. In the amplitudes, scalar and pseudo scalar form factor generating sigma terms manifest by themselves. Physical implications and roles of the scalar and the pseudo scalar form factor in pion weak-production are also discussed.
119204961
Ambiguities of neutrino (antineutrino) scattering on the nucleon due to the uncertainties of relevant strangeness form factors
Strange quark contributions to the neutrino (antineutrino) scattering on the nucleon level are investigated in the quasi-elastic region. Incident energy is used at 500 MeV for the scattering. All of the physical observables by the scattering are investigated within available experimental and theoretical results for strangeness form factors of the nucleon. Specifically, a newly combined datum of the parity violating electron scattering and the neutrino scattering is exploited for the strangeness form factors. Feasible quantities to be explored for the strangeness contents are discussed for the application to the neutrino–nucleus scattering.
119821537
The in-medium effects on the neutrino reaction in dense matter
The nucleon form factors in free space are usually thought to be modified when a nucleon is bound in a nucleus or immersed in a nuclear medium. We investigated effects of the density-dependent axial and weak-vector form factors on the electro-neutrino (νe) and anti-electro-neutrino (νe) reactions with incident energy Ev ≤ 80 MeV via neutral current (NC) and charged current (CC) for a nucleon in a nuclear medium or 12C. For the density-dependent form factors, we exploited the quark-meson-coupling (QMC) model, and apply them to the νe and νe induced reactions by NC and CC. In CC reaction, about 5 % decrease of the electro neutrino (νe) reaction cross section on the nucleon is shown to be occurred in normal density, ρ = ρ0∼0.15fm−3, and also about 5 % reduction of total νe cross section on 12C is obtained by the modification of the weak form factors for bound nucleons. Density effects for both cases are relatively small, but they are as large as the effect by the Coulomb distortion of outgoing leptons in t...
121016358
Lifetime of a Nuclear Excited State in Cascade Decay
It is shown that the lifetime of a nuclear excited state in the region of femtoseconds could be accurately measured by a precision measurement facility of a flat crystal spectrometer, if the angular correlation of two successive γ-rays in cascade decay is taken into account in the Doppler shift attenuation method.
121132966
ANALYSES OF THE KAON PHOTO- AND ELECTRO-PRODUCTION IN THE ISOBAR MODEL
37323655
Coulomb sum rule in the quasielastic region
Within a relativistic single particle model, we calculate the Coulomb sum rule of inclusive electron scattering from {sup 40}Ca and {sup 208}Pb in the quasielastic region. Theoretical longitudinal and transverse structure functions are extracted for three-momentum transfers from 300 to 500 MeV/c and compared with the experimental data measured at Bates and Saclay. We find that there is no drastic suppression of the longitudinal structure function and that the Coulomb sum rule depends on the nucleus in our theoretical model.
118406337
Coherent/incoherent metal transition in a holographic model
A bstractWe study AC electric (σ), thermoelectric (α), and thermal κ¯$$ \left(\overline{\kappa}\right) $$ conductivities in a holographic model, which is based on 3+1 dimensional Einstein-Maxwell-scalar action. There is momentum relaxation due to massless scalar fields linear to spatial coordinate. The model has three field theory parameters: temperature (T), chemical potential (μ), and effective impurity (β). At low frequencies, if β < μ, all three AC conductivities (σ, α,κ¯$$ \overline{\kappa} $$) exhibit a Drude peak modified by pair creation contribution (coherent metal). The parameters of this modified Drude peak are obtained analytically. In particular, if β ≪ μ the relaxation time of electric conductivity approaches to 23μ/β2$$ 2\sqrt{3\mu }/{\beta}^2 $$ and the modified Drude peak becomes a standard Drude peak. If β > μ the shape of peak deviates from the Drude form (incoherent metal). At intermediate frequencies (T < ω < μ), we have analysed numerical data of three conductivities (σ, α,κ¯$$ \overline{\kappa} $$) for a wide variety of parameters, searching for scaling laws, which are expected from either experimental results on cuprates superconductors or some holographic models. In the model we study, we find no clear signs of scaling behaviour.