LABORATORI NAZIONALI DEL SUD
The R-matrix formalism of Lane and Thomas1 has been extended to the relativistic case so that the many-coupled channels problem may be solved for systems in which binary breakup channels satisfy a relative Dirac equation. The formalism was applied to the relativistic impulse approximation2 (RIA) and also to Quantum Hadrodynamics3 (QHD) in the continuum Tamm-Dancoff approximation (TDA) with the classical meson fields replaced by one-meson exchange potentials using Dirac oscillator basis functions4 . It was shown5 that the common local density approximation for the exchange terms was inadequate in relativistic calculations. The discrepancy between the exact and the local density approximation calculations was traced to the extreme difference between the matrix elements of the negative energy states of the basis functions and hence a relativistic effect. Application of the formalism to the relativistic continuum TDA calculations for 16O showed6 that even the simple exchange with QHD coupling constants provides reasonable agreement with experimentally determined single particle energies and 15N(p,p) cross section at 39.84 MeV and hence is a justifiable interaction for later use in knockout reactions. 1. A. M. Lane and R. G. Thomas, Rev. Mod. Phys. 30, 257 (1958). 2. C. J. Horowitz, Phys. Rev. C 31, 1340 (1985). 3. B. D. Serot and J. D. Walecka, Advances in Nuclear Physics, ed. by J. W. Negele and E. Vogt (Plenum, NY, 1986). 4. M. Moshinsky and A. Szczepaniak, J. Phys. A 22, L817 (1989). 5. J. Grineviciute and D. Halderson, Phys. Rev. C 80, 044607 (2009). 6. J. Grineviciute and D. Halderson, to be published in Phys. Rev. C.

DATA: 21-05-2012

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