Hard breakup of the deuteron into two Delta-isobars

Abstract

We study high energy photodisintegration of the deuteron into two $\Delta$-isobars at large center of mass angles within the QCD hard rescattering model (HRM). According to the HRM, the process develops in three main steps: the photon knocks the quark from one of the nucleons in the deuteron; the struck quark rescatters off a quark from the other nucleon sharing the high energy of the photon; then the energetic quarks recombine into two outgoing baryons which have large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of $pn\rightarrow \Delta\Delta$ scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. Calculations show that the angular distribution and the strength of the photodisintegration is mainly determined by the properties of the $pn\rightarrow \Delta\Delta$ scattering. We predict that the cross section of the deuteron breakup to $\Delta^{++}\Delta^{-}$ is 4-5 times larger than that of the breakup to the $\Delta^{+}\Delta^{0}$ channel. Also, the angular distributions for these two channels are markedly different. These can be compared with the predictions based on the assumption that two hard $\Delta$-isobars are the result of the disintegration of the preexisting $\Delta\Delta$ components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both $\Delta^{++}\Delta^{-}$ and $\Delta^{+}\Delta^{0}$ channels to be similar.Comment: 17 pages, 3 figure