Related papers: Photon Dispersion in a Supernova Core
We calculate the nucleon contribution to the photon self-energy in a plasma, including the effect of the anomalous magnetic moment of the nucleons. General formulas for the transverse and longitudinal components of the self-energy are…
Mohanty and Samal have shown that the magnetic-moment interaction with nucleons contributes significantly to the photon dispersion relation in a supernova core, and with an opposite sign relative to the usual plasma effect. Because of a…
The electromagnetic two-body interaction energy is modified in the thermal environment of the solar core. The modifications are shown to imply a gross violation of standard solar physics unless the dispersion relation \omega_t(k) for the…
We study the transverse propagation of photons in a magnetized vacuum considering radiative corrections in the one-loop approximation. The dispersion equation is modified due to the magnetized photon self-energy in the transparency region…
The helicity changing Cerenkov radiation in a supernova core was used earlier to put a restrictive bound on the neutrino magnetic moment. Subsequently it was pointed out, that this result was based on a numerical error in the calculationn…
We construct the formula for the photonuclear total absorption cross section using the projection method and the unitarity relation. Our treatment is very effective when interference effects in the absorption processes on a nucleon are…
The formation of neutrino spectra in a supernova depends crucially on strength and inelasticity of weak interactions in hot nuclear matter. Neutrino interactions with nonrelativistic nucleons are mainly governed by the dynamical structure…
Elastic scattering on nucleons, \nu N -> N \nu, is the dominant supernova (SN) opacity source for \mu and \tau neutrinos. The dominant energy- and number-changing processes were thought to be \nu e^- -> e^- \nu and \nu\bar \nu <-> e^+ e^-…
We show that in a supernova core the longitudinal photon (plasmon) has a space-like dispersion and Cerenkov absorption and emission of such photons is kinematically allowed. If the neutrino has a non-zero magnetic moment, then helicity…
A new sum rule for $\gamma_\pi$, the backward spin polarizability of the nucleon, is derived from a backward-angle dispersion relation. Taking into account single- and multi-pion photoproduction in the s-channel up to the energy 1.5 GeV and…
Solutions to the energy-independent (gray) radiative transfer equations are compared to results of Monte Carlo simulations of the \Ni and \Co radioactive decay \GR energy deposition in supernovae. The comparison shows that an effective,…
A recently developed model for $\rho$-meson propagation in dense hadronic matter is applied to total photoabsorption cross sections in $\gamma$-proton and $\gamma$-nucleus reactions. Within the vector dominance model the photon coupling to…
Collective pair conversion $\nu_e\bar\nu_e\leftrightarrow \nu_{x}\bar\nu_{x}$ by forward scattering, where $x=\mu$ or $\tau$, may be generic for supernova neutrino transport. Depending on the local angular intensity of the electron lepton…
In a nuclear medium, spin-dependent forces cause the nucleon spins to fluctuate with a rate $\Gamma_\sigma$. We have previously shown that as a consequence the effective axial-current neutrino-nucleon scattering cross section is reduced.…
Extrapolation of perturbative nucleon spin fluctuation rates seems to suggest a strong suppression of weak interactions in supernova cores. We derive a new sum rule for the dynamical spin-density structure function which relates the spin…
Calculations have been performed for the $^{16}$O($\gamma$,pn) and the $^{16}$O($\gamma$,pp) reaction in the photon-energy range $E_{\gamma}$ = 60-300 MeV. Besides the contribution from the more common photoabsorption on the pionic degrees…
We analyzed the presently available experimental data on nucleon electromagnetic form factors within a multipole model based on dispersion relations. A good fit of the data is achieved by considering the coefficients of the multipole…
We develop a simple model for the evolution of a nucleon spin in a hot and dense nuclear medium. A given nucleon is limited to one-dimensional motion in a distribution of external, spin-dependent scattering potentials. We calculate the…
Compton scattering by the proton has been measured using the tagged-photon facility at MAMI (Mainz) and the large-acceptance arrangement LARA. The new data are interpreted in terms of dispersion theory based on the SAID-SM99K…
Using the multipole expansion we analyze photo induced reactions in an ultra-cold atomic gas composed of identical neutral bosons. While the Frank-Condon factor dominates the photo induced spin-flip reactions, we have found that for…