one of us (C.M.M.) was supported by FAPESP, Brazilian Agency.

[99]{}

W. N. Cottingham and R. Vinh Mau, Phys. Rev. [**130**]{} (1963) 735.

W. N. Cottingham, M. Lacombe, B. Loiseau, J-M. Richard and R. Vinh Mau, Phys. Rev. [**D8**]{} (1973) 800; M. Lacombe, B. Loiseau, J. M. Richard, R. Vinh Mau, P. Pires and R. Tourreil, Phys. Rev. [**D21**]{} (1980) 861.

G. E. Brown and J. W. Durso, Phys. Lett. [**B435**]{} (1971) 120.

C. Ordóñez and U. van Kolck, Phys. Lett. [**B291**]{}(1992) 459; L. S. Celenza, A. Pantziris and C. M. Shakin, Phys. Rev. [**C46**]{} (1992) 2213; J. L. Friar and S. A. Coon, Phys. Rev. [**C49**]{} (1994) 1272; C. A. da Rocha and M. R. Robilotta, Phys. Rev. [**C49**]{} (1994); M.C. Birse, Phys. Rev [**C49**]{} (1994) 2212; C. A. da Rocha and M. R.Robilotta, Phys. Rev [**C52**]{} (1995) 531.

C. Ordóñez, L. Ray and U. van Kolck, Phys. Lett. [**72**]{} (1994) 1982; Phys. Rev. [**C53**]{} (1996) 2086.

M. R. Robilotta, Nucl. Phys. [**A595**]{} (1995) 171; M. R. Robilotta and C. A. da Rocha, Nucl. Phys. [**A615**]{} (1997) 391

J. L. Ballot, M. R. Robilotta and C. A. da Rocha, to appear in Phys.Rev. C.

N. Kaiser, R. Brockmann and 