0000000000230326
AUTHOR
K. M. Schmitt
Survey on polarization observables in deuteron photodisintegration below pion-production threshold
Polarization observables of deuteron photodisintegration with polarized photons and oriented deuterons are systematically investigated below π-production threshold with respect to their sensitivity to subnuclear degrees of freedom and relativistic effects, to the different electric and magnetic multipole contributions, and to various realistic potential models. In particular, a complete survey on all single- and double-polarization observables like beam and target asymmetries of the differential cross section, nucleon polarization and proton-neutron spin correlation is given.
Deuteron photodisintegration at low energies
All presently available experimental data on deuteron photodisintegration below 40 MeV (i.e., total and differential cross sections, photon asymmetry and neutron polarization) are collected and carefully compared with the present status of the conventional theory (i.e., in the framework of mesontheoretical or semi-phenomenologicalN-N potentials including subnuclear degrees of freedom and relativistic corrections). No significant evidence for a failure of the conventional theory is found within the present experimental accuracy.
Relations between polarization observables and complete sets for deuteron photodisintegration
The polarization observables for deuteron photodisintegration are given as Hermitean forms of theT-matrix elementsti. By inversion we are able to express a given productti*tj in terms of polarization observables. This allows (i) to derive linear relations between observables for unpolarized, circularly and linearly polarized photons, (ii) to construct explicitly complete sets of polarization observables, and (iii) to derive quadratic relations between observables.
Meson-retardation effects in deuteron photodisintegration below ?-threshold
Mesor-retardation effects in photodisintegration of the deuteron below pion threshold are studied by constructing retarded one-boson-exchange potentials using time-dependent non-covariant perturbation theory. The corresponding retarded meson-exchange currents including retarded vertex currents are derived analogously by gauge-invariant minimal coupling. It is found that retardation effects in the wave functions and in the electromagnetic currents as well have a significant influence on total and differential cross sections.
Deuteron photodisintegration with the Bonn OBE potentials
The various OBE approximations to the recent Bonn potential are studied in deuteron photodisintegration below π-threshold. Consistent static meson-exchange currents, isobar currents, and the relativistic spin-orbit current are included. Concerning the OBEPT also the leading retardation corrections in the currents are taken into account. Comparison with experimental data is carried out in detail.
Heavy-mesons exchange and the backward deuteron electrodisintegration
Backward electrodisintegration of the deuteron is calculated using an exchange-current operator containing π, η, ρ, ω, δ, σ, andA1 exchanges. The deuteron and1S0np wave functions are derived from the Bonn OBEPs. For completeness, we introduced theA1-meson exchange into the OBEP's as well. As a consequence, the value ofD-state probabilityPD is increased by 0.2%–0.8%. The computed cross sections are compared with new data.
Integrated photoabsorption strength and sum rules for a bound Dirac particle
Relativistic effects in the integrated total photoabsorption cross section are discussed using a simple model of a Dirac particle bound in a central potential of scalar or vector type. The integrated strength is calculated explicitly and compared to a new relativistic extension of the TRK-sum rule using positive energy projection and to predictions from dispersion relations. M1 and E2 sum rules are also considered. In all cases the integrated strength exceeds the classical sum rule up to a few percent. The dispersion sum rule cannot be compared directly to the integrated strength since it contains a negative contribution from pair production in the potential field which is of the order of a…