Phenomenological Lagrangian approach to the electromagnetic deuteron form factors

A phenomenological Lagrangian approach is employed to study the electromagnetic properties of the deuteron. The deuteron is regarded as a weakly bound state of the proton and neutron. We construct a general form for the electromagnetic one- and two-body transition operators formulated in terms of the nucleon fields, which are then used in the calculation of the electromagnetic deuteron form factors. One of the two-body operators is responsible for explaining the quadrupole moment form factor. We show that in our approach the data on the deuteron form factors as well as on the differential cross section of elastic electron-deuteron scattering are well explained.Comment: 17 pages, 18 figure

Exchange current contributions in null-plane quantum models of elastic electron deuteron scattering

We investigate exchange current contributions to elastic electron-deuteron scattering using exactly Poincar\'e invariant quantum mechanics with a null-plane kinematic symmetry. Our model exchange current is motivated by one-pion-exchange physics. Exact current conservation and current covariance are satisfied by using this current to compute a linearly independent set of current matrix elements. The remaining current matrix elements are generated from the independent matrix elements using the covariance and current conservation constraints. The presence of the exchange current increases the sensitivity to the choice of independent current matrix elements. Two choices of independent matrix elements that have distinct motivations lead to a good description of all of the elastic scattering observables for momentum transfers below 8 (GeV)$^2$.Comment: 49 Pages, 24 figure

Transition between nuclear and quark-gluon descriptions of hadrons and light nuclei

We provide a perspective on studies aimed at observing the transition between hadronic and quark-gluonic descriptions of reactions involving light nuclei. We begin by summarizing the results for relatively simple reactions such as the pion form factor and the neutral pion transition form factor as well as that for the nucleon and end with exclusive photoreactions in our simplest nuclei. A particular focus will be on reactions involving the deuteron. It is noted that a firm understanding of these issues is essential for unraveling important structure information from processes such as deeply virtual Compton scattering as well as deeply virtual meson production. The connection to exotic phenomena such as color transparency will be discussed. A number of outstanding challenges will require new experiments at modern facilities on the horizon as well as further theoretical developments.Comment: 37 pages, 17 figures, submitted to Reports on Progress in Physic