Meson cloud contributions to the Dalitz decays of decuplet to octet baryons

Abstract

We study the role of the meson cloud on the electromagnetic transitions from decuplet ($B^{\prime }$) to octet ($B$) baryons in terms of the squared four-momentum transfer $q^2$. In the quark model framework, the meson cloud dressing of the quark cores gives important contributions to the ${\gamma }^{\ast }N\to \Delta (1232)$ transition form factors. In the present work, we estimate the meson cloud contributions of all decuplet to octet baryon transitions (${\gamma }^{\ast }B\to B^{\prime }$ or $B^{\prime }\to {\gamma }^{\ast }B$). Models that combine valence quark effects with pion and kaon cloud dressing provide a fair description of the radiative decays of decuplet to octet baryons, namely the ${\Sigma }^0(1385)\to \gamma \Lambda (1116)$ and ${\Sigma }^{+}(1385)\to \gamma {\Sigma }^{+}(1193)$ decays. Previous studies indicated the relevance of the pion cloud effects on the $B^{\prime }\to {\gamma }^{\ast }B$ transition, but also suggested that the kaon cloud contributions may be important in the timelike region. We combine then the contributions of the bare core, estimated by a covariant quark model, with $q^2$-dependent contributions of pion and kaon clouds. We use the framework to calculate the Dalitz decay rates and the Dalitz decay widths of decuplet baryons in octet baryons with di-electrons ($B^{\prime }\to e^{+}{e}^{-}B$) or di-muons ($B^{\prime }\to {\mu }^{+}{\mu }^{-}B$). We conclude, based on the magnitude of our results, that most estimates of the $B^{\prime }\to e^{+}{e}^{-}B$ Dalitz decay widths may be tested at HADES and PANDA (GSI) in a near future. We discuss also the possibility of measuring the $\Delta (1232)\to {\mu }^{+}{\mu }^{-}N$ and ${\Sigma }^0(1385)\to {\mu }^{+}{\mu }^{-}\Lambda (1116)$ decay widths in some facilities, based on the estimated branching ratios.

Comments: Published at Phys. Rev. D. 28 pages, 8 figures, 11 tables. More compacted version. Appendix removed. Updated bibliography