标题： 带有扭力的f(R)引力：在J-丛框架下的几何方法 显示英文标题

标题： f(R) gravity with torsion: a geometric approach within the J-bundles framework

摘要： 我们讨论在射流束框架下的具有扭率的f(R)引力理论。 这种方法特别有用，因为扭率和曲率张量的分量可以作为束上的纤维射流坐标，然后可以轻松获得该理论的对称性和守恒定律。 研究了在真空以及存在各种物质形式（如狄拉克场、杨-米尔斯场和自旋完美流体）情况下的f(R)引力场方程。 这些场扩展了射流束框架并描述了动力学。 最后我们给出了一些宇宙学应用，并讨论了f(R)引力与标量-张量理论之间的关系。 显示英文摘要

摘要： We discuss the f(R)-theories of gravity with torsion in the framework of jet-bundles. Such an approach is particularly useful since the components of the torsion and curvature tensors can be chosen as fiber jet-coordinates on the bundles and then the symmetries and the conservation laws of the theory can be easily achieved. Field equations of f(R)-gravity are studied in empty space and in presence of various forms of matter as Dirac fields, Yang--Mills fields and spin perfect fluid. Such fields enlarge the jet-bundles framework and characterize the dynamics. Finally we give some cosmological applications and discuss the relations between f(R)-gravity and scalar-tensor theories.