Massless DKP fields in Riemann-Cartan space-times
  We study massless Duffin-Kemmer-Petiau (DKP) fields in the context of Einstein-Cartan gravitation theory, interacting via minimal coupling procedure. In the case of an identically vanishing torsion (Riemannian space-times) we show that there exists local gauge symmetries which reproduce the usual gauge symmetries for the massless scalar and electromagnetic fields. On the other hand, similarly to what happens with the Maxwell theory, a non-vanishing torsion, in general, breaks the usual U(1) local gauge symmetry of the electromagnetic field or, in a different point of view, impose conditions on the torsion. 
R. Casana, V.Ya. Fainberg, B.M. Pimentel (Sao Paulo, IFT), J.T.   Lunardi (Ponta Grossa State U.) and R.G. Teixeira (Sao Jud...