Charmed-baryon production in antiproton-proton collisions within an effective Lagrangian model

We study the productions of charmed baryons ${\bar \Lambda}_c^- \Lambda_c^+$, ${\bar \Lambda}_c^- \Sigma_c^+$, and ${\bar \Sigma}^- \Sigma_c^+$ in the antiproton-proton collisions within an effective Lagrangian model that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The baryon production proceeds via the $t$-channel exchanges of $D^0$ and $D^{*0}$ mesons in the initial collision of the antiproton with the target proton. The distortion effects in the initial and final states are accounted for by using an eikonal approximation-based procedure. We find that the reaction amplitudes of all the production channels are dominated by the $D^{*0}$ meson-exchange diagrams. We discuss the relative roles of tensor and vector components of the $D^{*0}$ coupling in the $D^{*0}$ meson-exchange component of the total production cross sections. The magnitudes of the cross sections are predicted for each final state for the range of beam momenta of relevance to the ${\bar P}ANDA$ experiment.Comment: 16 pages, 5 figures. typos corrected, version accepted for publication in Phys. Rev. D. arXiv admin note: text overlap with arXiv:1406.707

Production of Ξ−\Xi^--hypernuclei via the (K−,K+K^-,K^+) reaction in a quark-meson coupling model

We study the production of $\Xi^-$-hypernuclei, $^{12}_{\Xi^{-}}$Be and $^{28}_{\Xi^{-}}$Mg, via the ($K^-,K^+$) reaction within a covariant effective Lagrangian model, employing the bound $\Xi^-$ and proton spinors calculated by the latest quark-meson coupling model. The present treatment yields the $0^\circ$ differential cross sections for the formation of simple s-state $\Xi^-$ particle-hole states peak at a beam momentum around 1.0 GeV/c with a value in excess of 1 $\mu$b.Comment: Accepted version with miner changes, 4 pages, 2 figures, Presented at the 20th International IUPAP Conference on Few-Body Problems in Physics, 20 - 25 August, 2012, Fukuoka, Japa

Dilepton production in nucleon-nucleon collisions around 1 GeV/nucleon: a theoretical update

We present a fully relativistic and gauge invariant framework for calculating the cross sections of dilepton production in nucleon-nucleon (NN) collisions which is based on the meson-exchange approximation for the NN scattering amplitudes. Predictions of our model are compared with those of other covariant models that have been used to describe this reaction. We discuss the comparison of our calculations with the old DLS and the recent HADES data.Comment: 9 pages, 7 figures, to appear in proc. of the International Symposium on Nuclear Physics, Mumbai, India, Dec. 8-12, 2009

E2 component in subcoulomb breakup of ^{8}B

We calculate the angular distribution and total cross section of the ^{7}Be fragment emitted in the break up reaction of ^{8}B on ^{58}Ni and ^{208}Pb targets at the subCoulomb beam energy of 25.8 MeV, within the non-relativistic theory of Coulomb excitation with proper three-body kinematics. The relative contributions of the E1, E2 and M1 multipolarities to the cross sections are determined. The E2 component makes up about 65% and 40% of the ^{7}Be total cross section for the ^{58}Ni and ^{208}Pb targets respectively. We find that the extraction of the astrophysical S-factor, S_{17}(0), for the ^{7}Be(p,\gamma)^8B reaction at solar energies from the measurements of the cross sections of the ^{7}Be fragment in the Coulomb dissociation of ^{8}B at sub-Coulomb energies is still not free from the uncertainties of the E2 component.Comment: Revised version (correcting earlier errors) submitted to Phys. Letts.