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Di-Electron Bremsstrahlung in Intermediate-Energy pn and Dp Collisions

L. P. Kaptari·B. Kampfer
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Abstract

Invariant mass spectra of di-electrons stemming from bremsstrahlung processes are calculated in a covariant diagrammatical approach for the exclusive reaction D p \to p_{\rm sp} n p e^+ e^- with detection of a forward spectator proton, p_{sp}. We employ an effective nucleon-meson theory for parameterizing the sub-reaction n p \to n p e^+ e^- and, within the Bethe-Salpeter formalism, derive a factorization of the cross section in the form {dσ_{D p \to p_{\rm sp} n p e^+ e^-}}/{dM}= {dσ_{n p \to n p e^+ e^-}}/{dM} \times kinematical factor related solely to the deuteron (M is the e^+ e^- invariant mass). The effective nucleon-meson interactions, including the exchange mesons π, σ, ωand ρas well as excitation and radiative decay of Δ(1232), have been adjusted to the process pp \to pp e^+ e^- at energies below the vector meson production threshold. At higher energies, contributions from ωand ρmeson excitations are analyzed in both, NN and Dp collisions. A relation to two-step models is discussed. Subthreshold di-electron production in Dp collisions at low spectator momenta is investigated as well. Calculations have been performed for kinematical conditions envisaged for forthcoming experiments at HADES.

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L. P. Kaptari, B. Kampfer. 2005-10-14. Di-Electron Bremsstrahlung in Intermediate-Energy pn and Dp Collisions. https://doi.org/10.1016/j.nuclphysa.2005.10.007

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