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Register a new user$Delta$-mass dependence of the M-matrix in the calculation of $mbox{N}Deltato mbox{NN}$ cross sections
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Within the one boson exchange model, $Delta$-mass dependent M-matrix and its influence on the calculation of $NDelta to NN$ cross sections are investigated. Our calculations show that the $m_{Delta}$ dependence of $|textbf{p}_{NDelta}|$ and $|mathcal{M}|^2$ has effects on the calculations of $sigma_{NDeltato NN}$, especially around the threshold energy. We finally provide a table of accurate $sigma_{NDeltato NN}$ which can be used in the transport models.
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The in-medium $NNrightarrow NDelta$ cross section and its differential cross section in isospin asymmetric nuclear medium are investigated in the framework of the one-boson exchange model by including the isovector mesons, i.e., $delta$ and $rho$ mesons. Our results show that the in-medium $NNrightarrow NDelta$ cross sections are suppressed with density increasing, and the differential cross sections become isotropic with the density increasing at the beam energy around the $Delta$ threshold energy. The isospin splitting on the medium correction factor, $R=sigma_{ NNrightarrow NDelta}^*/sigma_{NNrightarrow NDelta}^{text{free}}$ is observed for different channels of $NNto NDelta$, especially around the threshold energy for all the effective Lagrangian parameters. By analyzing the selected effective Lagrangian parameters, our results show that the larger effective mass is, the weaker medium correction $R$ is.
In this paper, the in-medium $NNrightarrow NDelta$ cross section is calculated in the framework of the one-boson exchange model by including the isovector mesons, i.e. $delta$ and $rho$ mesons. Due to the isospin exchange in the $NNrightarrow NDelta$ process, the vector self-energies of the outgoing particles are modified relative to the incoming particles in isospin asymmetric nuclear matter, and it leads to the effective energies of the incoming $NN$ pair being different from the outgoing $NDelta$ pair. This effect is investigated in the calculation of the in-medium $NNrightarrow NDelta$ cross section. With the corrected energy conservation, the cross sections of the $Delta^{++}$ and $Delta^+$ channels are suppressed, and the cross sections of the $Delta^0$ and $Delta^-$ channels are enhanced relative to the results obtained without properly considering the potential energy changes. Our results further confirm the dependence of medium correction factor, $R=sigma_{ NNrightarrow NDelta}^*/sigma_{NNrightarrow NDelta}^{text{free}}$, on the charge state of $NNrightarrow NDelta$ especially around the threshold energy, but the isospin splitting of medium correction factor $R$ becomes weak at high beam energies.
This paper presents measurements of production cross sections and inelastic cross sections for the following reactions: 60 GeV/$c$ protons with C, Be, Al targets and 120 GeV/$c$ protons with C and Be targets. The analysis was performed using the NA61/SHINE spectrometer at the CERN SPS. First measurements were obtained using protons at 120 GeV/$c$, while the results for protons at 60 GeV/$c$ were compared with previously published measurements. These interaction cross section measurements are critical inputs for neutrino flux prediction in current and future accelerator-based long-baseline neutrino experiments.
We perform a direct finite nucleus calculation of the partial width of a bound Delta isobar decaying through the non-mesonic decay mode, Delta N -> NN. This transition is modeled by the exchange of the long ranged pi meson and the shorter ranged rho meson. The contribution of this decay channel is found to be approximately 60 % of the decay width of the Delta particle in free space. Considering the additional pionic decay mode, we conclude that the total decay width of a bound Delta resonance in nuclei is of the order of 100 MeV and, consequently, no narrow Delta nuclear states exist, contrary to recent claims in the literature. Our results are in complete agreement with microscopic many-body calculations and phenomenological approaches performed in nuclear matter.
Electrical conductivity and high dielectric constant are in principle self-excluding, which makes the terms insulator and dielectric usually synonymous. This is certainly true when the electrical carriers are electrons, but not necessarily in a material where ions are extremely mobile, electronic conduction is negligible and the charge transfer at the interface is immaterial. Here we demonstrate in a perovskite-derived structure containing five-coordinated Ti atoms, a colossal dielectric constant (up to $mbox{10}^9$) together with very high ionic conduction $mbox{10}^{-3}mbox{S.cm}^{-1}$ at room temperature. Coupled investigations of I-V and dielectric constant behavior allow to demonstrate that, due to ion migration and accumulation, this material behaves like a giant dipole, exhibiting colossal electrical polarization (of the order of $mbox{0.1,C.cm}^{-2}$). Therefore, it may be considered as a ferro-ionet and is extremely promising in terms of applications.
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