Hard breakup of the deuteron into twoΔisobars

Abstract

We study high energy photodisintegration of the deuteron into two ∆-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 a 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 → ∆∆ 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 → ∆∆ scattering. We predict that the cross section of the deuteron breakup to ∆ ++ ∆ − is 4-5 times larger than that of the breakup to the ∆ + ∆ 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 ∆-isobars are the result of the disintegration of the preexisting ∆∆ components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both ∆ ++ ∆ − and ∆ + ∆ 0 channels to be similar.

Partonic angular momentum in the nucleon's chiral periphery

“…The first-quantized operator representing the EMT component T +T is given by the average pion transverse momentum k T . Similar results are obtained for the matrix elements of the other EMT components and the invariant form factors [18]. For expressing the transverse densities it is convenient to use the transverse coordinate representation of the N → πB LF wave function,…”

“…(8) and the AM density Eq. (9) studied in the present work [18]. We can also compute the peripheral T +T and T ++ currents for transverse nucleon polarization and explore possible LF densities of transverse AM [31].…”

“…1c. The equivalence of the two methods has been demonstrated at the analytic and numerical level; the explicit expressions will be given elsewhere [18].…”

“…As results of this study we (a) estimate the peripheral AM in the nucleon from first principles, (b) validate the concept of transverse AM density [4,6], (c) obtain a simple mechanical picture of peripheral nucleon structure. Details will be provided in a forthcoming article [18].…”

Modern studies of the Deuteron: From the lab frame to the light front

“…Finally, the deuteron structure can be probed in deep-inelastic hard processes such as hard break-up of the deuteron [54,55] and deep-inelstic electro-productions of photons and vector mesons aimed at studies of the generalized partonic distributions in the deuteron (see e.g [56,57]). …”