Accioly A.; Ragusa S.; Mukai H.; Rey Neto E. de
الوصف:
We consider a model for gravity in which the linear part of the four-derivative terms <FONT FACE=Symbol>ò</FONT>R<FONT FACE=Symbol>mn</FONT> R<FONT FACE=Symbol>mn</FONT> <img src="http:/img/fbpe/bjp/v30n3/11eq01.gif" border="0" align="absmiddle">d4 x and <FONT FACE=Symbol>ò</FONT>R² <img src="http:/img/fbpe/bjp/v30n3/11eq01.gif" border="0" align="absmiddle">d4 x are included into the Fierz-Pauli gravitational action. Unitarity is discussed at the tree-level. The issue of the gravitational deflection of a light ray is also considered.