A fully relativistic description of Hypernuclear production in proton- and pion-Nucleus Collisions

Exclusive A(p,K^+){_\Lambda}B and A(\pi,K^+){_\Lambda}B^\prime reactions leading to two body final states, have been investigated in a fully covariant model based on an effective Lagrangian picture. The explicit kaon production vertex is described via creation, propagation and decay into relevant channel of N*(1650), N*(1710) and N*(1720) intermediate baryonic resonance states, in the initial collision of the projectile with one of the target nucleons. The bound state wave functions are obtained by solving the Dirac equation with appropriate scalar and vector potentials. The calculated cross sections show strong sensitivity to the final hypernuclear state excited in the reaction. Cross sections of 1 - 2 nb/sr are obtained at peak positions of favored transitions in case of the A(p,K^+){_\Lambda}B reaction on heavier targets.Comment: 4 pages, 6 figures, Talk presented in the International Conference on Hypernuclear and Strange Particle Physics (HYP 2006). To Appear in Eur. Phys. J.

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

Breakup Reactions of Drip Line Nuclei

The formal theory of breakup reactions is reviewed. The direct breakup mechanism which is formulated within the framework of the post form distorted wave Born approximation is discussed in detail. In this theory, which requires the information about only the ground state wave function of the projectile, the fragment-target interactions are included to all orders while fragment-fragment interaction is treated only in the first order. The general applicability of this theory to describe the breakup of halo nuclei is demonstrated by comparing the calculations with data for total, as well as energy and angle integrated cross sections and momentum distributions of fragments in reactions induced by a number of halo nuclei. We investigate the role played by the pure Coulomb, pure nuclear and the Coulomb-nuclear interference terms. Postacceleration effects in the Coulomb breakup of neutron halo nuclei is also studied.Comment: 45 pages latex, 16 figures, Lectures presented in the workshop on ``Nuclei at Extremes of Isospin and Mass'' held at Toshali Sands, Puri, March 11 - 22, 2003. (Some typos and references corrected.

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

Spectroscopy of one-neutron halo nuclei from the Coulomb breakup reactions

We review the current status of obtaining the spectroscopic information on the one-neutron halo nuclei from the Coulomb breakup reactions. The theory of these reactions formulated in the framework of the Distorted Wave Born Approximation, allows the use of the realistic wave functions corresponding to any orbital angular momentum structure for the core-valence neutron relative motion in the ground state of the projectile. The energy, angular and parallel momentum distributions of the projectile fragments calculated within this theory are selective about the ground state wave function of the projectile. Therefore, firm conclusions can be drawn about the structure of the projectile ground state by comparing the calculations with the corresponding data.Comment: 14 pages latex, 6 figures. Talk presented at the international workshop on Production of Radioactive Ion Beams (PRORIB-2001), held at Puri, India, Feb. 12 - 17, 200

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

Charm production in interactions of antiproton with proton and nuclei at PˉANDA{\bar P}ANDA energies

We study the production of charmed baryons in the antiproton-proton and antiproton-nucleus interactions within a fully covariant model that is based on an effective Lagrangian approach. The baryon production proceeds via the $t$-channel $D^0$ and $D^{*0}$ meson-exchange diagrams. We have also explored the production of the charm-baryon hypernucleus $^{16}_{\Lambda_c^+}$O in the antiproton - $^{16}$O collisions. For antiproton beam momenta of interest to the ${\bar P}ANDA$ experiment, the 0$^\circ$ differential cross sections for the formation of $^{16}_{\Lambda_c^+}$O hypernuclear states with simple particle-hole configurations, have magnitudes in the range of a few $\mu$b/sr.Comment: 5 pages, 3 figures, Talk presented at the conference "Light-Cone 2017", held at Mumbai India, Sept 18 - 22, 2017. Version as printed in the Journal. arXiv admin note: text overlap with arXiv:1701.0222

Description of the recently observed hypernucleus ^{15}{\!\!\!_{\Xi^-}}C within a quark-meson coupling model

We investigate within a quark-meson coupling (QMC) model, the structure of the bound $\Xi^-$ hypernucleus ^{15}{\!\!\!_{\Xi^-}}C ($^{14}$N + $\Xi^-$), which has been observed in a recent analysis of the KEK-E373 experiment. In the QMC model, light quarks in nonoverlapping nucleon and $\Xi^-$ bags interact self-consistently with isoscalar-scalar ($\sigma$), isoscalar-vector ($\omega$), and isovector-vector ($\rho$) mesons in the mean field approximation. The parameters of the model (quark-meson coupling constants and masses) are mostly fixed from the nuclear matter saturation properties. The QMC model closely reproduces the separation energies of the two $\Xi^-$ hyperon states in ^{15}{\!\!\!_{\Xi^-}}C reported in the KEK-E373 analysis, and identifies their quantum numbers. We also make predictions for the cross sections for the production of the ^{15}{\!\!\!_{\Xi^-}}C hypernuclear specta in the ($K^-, K^+$) reaction on a $^{15}$O target within a covariant effective Lagrangian model using the $\Xi^-$ bound state spinors obtained within the same QMC model.Comment: 17 Pages, 4 figure

Structure of ^{19}C from Coulomb dissociation studies

We investigate the structure of the neutron rich nucleus ^{19}C through studies of its breakup in the Coulomb field of target nuclei. The breakup amplitude is calculated within an adiabatic treatment of the projectile excitation, which allows the use of the realistic wave functions for the relative motion between the fragments in the ground state of the projectile. The angular distribution of the center of mass of ^{19}C, longitudinal momentum distribution of ^{18}C and relative energy spectrum of the fragments (neutron - ^{18}C) following the breakup of ^{19}C on heavy targets at beam energies below 100 MeV/nucleon have been computed using different configurations for the ground state wave function of ^{19}C. In all the cases, the data seem to favor a ^{18}C(0$^+)\otimes1s_{1/2}$ configuration for the ground state of ^{19}C, with the one-neutron separation energy of 0.53 MeV.Comment: Accepted for publication in Physical Review

Dilepton production in nucleon-nucleon collisions reexamined

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 earlier to describe this reaction. Our results are also compared with those of the semiclassical models which are employed to get the input elementary cross sections in the transport model calculations of the dilepton production in nucleus-nucleus collisions. It is found that cross sections obtained within the semiclassical and quantum mechanical models differ noticeably from each other.Comment: 13 pages, 5 figures, Title and Discussions modified, new references added, version to appear in Phys. Rev. C as a regular articl