Forwardp¯delastic scattering and total spin-dependentp¯d

Abstract

Spin-dependent totalpd cross sections are considered using the optical theorem. For this aim the full spin dependence of the forwardpd elastic scattering amplitude is considered in a model independent way. The single-scattering approximation is used to relate this amplitude to the elementary amplitudes ofpp andpn scattering and the deuteron form factor. A formalism allowing to take into account Coulomb-nuclear interference effects in polarizedpd cross sections is developed. Numerical calculations for the polarized totalpd cross sections are performed at beam energies 20-300 MeV using theNN interaction models developed by the Jülich group. Double-scattering effects are estimated within the Glauber approach and found to be in the order of 10-20%. Existing experimental data on differentialpd cross sections are in good agreement with the performed Glauber calculations. It is found that for the usedNN models the total longitudinal and transversalpd cross sections are comparable in absolute value to those forpp scattering.

Erratum: Refined Glauber model versus Faddeev calculations and experimental data for pd spin observables [Phys. Rev. C 81 , 014004 (2010)]

“…To solve this puzzle, one should recall that when considering scattering of antiprotons by light nuclei the validity of the Glauber model was found to begin at as low as 50 MeV [34]. The validity at such a low energy is with no doubts tightly related to strong absorption of antiprotons by the nuclear core, so that the central nuclear area (where the nuclear density is still noticeable) is seen by the incident antiproton as a large black disk, on which the diffraction is observed in such experiments.…”

Total spin-dependent p̄d cross sections at low and intermediate energies

“…For the elementarypN amplitudes we use those of the Jülich models A and D [10][11][12]. Details on the applied formalism can be found in [14]. In order to check the reliability of this approach we calculate the unpolarized total and differentialpd cross sections where we can compare our results with available experimental information.…”

“…The unit vector m is fixed by the direction of the beam momentum. One can find from (1) that only the cross sections σ 1 and σ 2 are connected with the spin-filtering mechanism [14] and, thus, determine the rate of the polarization buildup in the scattering of unpolarized antiprotons off polarized deuterons. The tensor cross section σ 3 is not related to the polarization of the beam and, therefore, is not relevant for the spin-filtering.…”

“…The pure Coulomb amplitude does not contribute to σ i , i = 1, 2, 3, but it gives an important contribution to σ 0 . In order to calculate the contribution of the Coulomb-nuclear interference terms one cannot use the optical theorem because of the Coulomb singularity at the scattering angle θ = 0 • , and therefore we use here the method of [4], adapted to to the case ofpd scattering [14]. For the polarized cross sections we use only the single-scattering approximation.…”

“…Considering the full spin dependence of the forwardpd elastic scattering amplitude [13,14] and using the optical theorem, one can find that the total polarizedpd cross section can be written as…”