• On duality in the born-infeld theory 

      Khoudeir, Adel; Parra, Yoan (SABER ULA, 2005-01-06)
      On duality in the born-infeld theory (Khoudeir, Adel; Parra, Yoan) Abstract The SL(2,R) duality symmetric action for the Born-Infeld theory in terms of two potentials, coupled with non-trivial backgroud fields in ...
    • On the general structure of Ricci collineations for type B warped spacetimes. 

      Flores, J. L.; Percoco, Umberto; Parra, Yoan (SABER ULA, 2005-08-18)
      On the general structure of Ricci collineations for type B warped spacetimes (Flores, J. L.; Parra, Yoan; Percoco, Umberto.) Abstract A complete study of the structure of Ricci collineations for type B warped spacetimes ...