Deuteron photo-disintegration with polarised photons in the energy range 30–50 MeV

Abstract

The reaction d( γ, np) has been studied using the tagged and polarised LADON gamma ray beam at an energy 30 − 50 M eV to investigate the existence of narrow dibaryonic resonances recently suggested from the experimental measurements in a different laboratory. The beam was obtained by Compton back-scattering of laser light on the electrons of the storage ring ADONE. Photo-neutron yields were measured at five neutron angle ϑ c.m.

Relativistic contributions to the deuteron photodisintegration in the Bethe-Salpeter formalism

“…Let us make some remarks on current conservation. The Mandelstam vertex consists of one-and two-body parts, Λ µ (p, k; P, K) = Λ [1] µ (p, k; P, K) + Λ [2] µ (p, k; P, K). The second part of the Mandelstam vertex determines two-body contributions of the conserved EM current.…”

“…[36] it was shown that the gauge independence condition for the elastic electrondeuteron scattering amplitude is fulfilled in the impulse approximation for many-rank separable BS kernels, implying that q · M [2] f i = 0. In case of the deuteron breakup in the final 2N state isospin I = 1 states are present, yielding a nonvanishing isovector contribution, q · M [2] f i = 0. Consequently the two-body Mandelstam current operator should be added to guarantee the gauge independence.…”

“…where E k = √ m 2 + k 2 and k denotes the restricted 4-vector k. The prescription leads to a relativistic equation of motion for the moving 2N system. By means of the boost it is transformed to the Schrödinger-type equation in the rest frame 2 .…”

“…Here it is worth-while to point out a performed experiment with the polarized LADON gamma ray beam [2] to investigate the existence of narrow dibaryonic resonances in reaction on nuclei at a low excitation energies, an experimental program carried out on the linearly polarized photon beam at YEREVAN Synchrotron to study the cross section asymmetry of the deuteron photodisintegration process in the energy range 0.9-1.7 GeV for proton center-of-mass angle of 90…”

“…At the present time deuteron photodisintegration is rated among the leading trends at experimental facilities around the world. Here it is worth-while to point out a performed experiment with the polarized LADON gamma ray beam [2] to investigate the existence of narrow dibaryonic resonances in reaction on nuclei at a low excitation energies, an experimental program carried out on the linearly polarized photon beam at YEREVAN Synchrotron to study the cross section asymmetry of the deuteron photodisintegration process in the energy range 0.9-1.7 GeV for proton center-of-mass angle of 90 • [3]. This is connected the problem of the validity of the constituent quark counting rules at energies of a few GeV.…”