Internal meson dominance for pp-bar annihilation.

Abstract

The previously considered $^{3}\mathrm{S}_{1}$ internal fusion model of pp\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}YY\ifmmode\bar\else\textasciimacron\fi{}, YY\ifmmode\bar\else\textasciimacron\fi{} $^{\mathrm{*}}$, and ${Y}^{\mathrm{*}}$Y${\ifmmode\bar\else\textasciimacron\fi{}}^{*}$ (Y denotes hyperon) at low energies is modified and thereby extended to also include pp\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}nn\ifmmode\bar\else\textasciimacron\fi{} and ${\ensuremath{\Delta}}^{++}$\ensuremath{\Delta}${\ifmmode\bar\else\textasciimacron\fi{}}^{\ensuremath{-}\ensuremath{-}}$. It is assumed that the same nonperturbative mechanism that mixes the different qq\ifmmode\bar\else\textasciimacron\fi{} pairs within the neutral, nonstrange mesons is also responsible for the scattering, annihilation, and creation of qq\ifmmode\bar\else\textasciimacron\fi{} pairs within the baryon-antibaryon system. More specifically, we assume that processes qq\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}QQ\ifmmode\bar\else\textasciimacron\fi{} within the baryon-antibaryon system with q=d or u and Q=d, u, or s quarks is mediated by fusion of the qq\ifmmode\bar\else\textasciimacron\fi{} to a pseudoscalar or vector meson that also within the system decays into QQ\ifmmode\bar\else\textasciimacron\fi{}. The $^{1}\mathrm{S}_{0}$ pseudoscalar-meson model disagrees with experiment whereas the $^{3}\mathrm{S}_{1}$ vector-meson fusion model is in reasonable agreement with it. As compared to the previously considered $^{3}\mathrm{S}_{1}$ internal fusion model the main change is an extension of the approximate agreement to the nonstrange final-state baryons. This is achieved since strange baryons in the model are only produced via the small \ensuremath{\omega}-\ensuremath{\varphi} mixing.