Energy conditions in arbitrary dimensions

Energy conditions for matter fields are comprehensively investigated in arbitrary n( 3) dimensions without specifying future and past directions locally. We classify an energy-momentum tensor into n-dimensional counterparts of the Hawking-Ellis types I to IV, where type III is defined by a more useful form than those adopted by Hawking and Ellis and other authors to identify the type-III energy-momentum tensor in a given spacetime.We also provide necessary and sufficient conditions for types I and II as inequalities for the orthonormal components of the energy-momentum tensor in a canonical form and show that types III and IV violate all the standard energy conditions. Lastly, we study energy conditions for a set of physically motivated matter fields.