Matter Lagrangian of particles and fluids

• Type: Article in International Scientific Journal
• Date: 2018

Authors

Avelino, PP (Author) FCUP; Sousa, L (Author) Other

Journal

Title: Physical Review D

Vol. 97

ISSN: 2470-0010

Publisher: American Physical Society

Indexing

ISI Web of Knowledge - 22 Citations

Scopus - 25 Citations

Other information

Authenticus ID: P-00N-TDT

DOI: 10.1103/physrevd.97.064019

Abstract (EN): We consider a model where particles are described as localized concentrations of energy, with fixed rest mass and structure, which are not significantly affected by their self-induced gravitational field. We show that the volume average of the on-shell matter Lagrangian L-m describing such particles, in the proper frame, is equal to the volume average of the trace T of the energy-momentum tensor in the same frame, independently of the particle's structure and constitution. Since both L-m and T are scalars, and thus independent of the reference frame, this result is also applicable to collections of moving particles and, in particular, to those which can be described by a perfect fluid. Our results are expected to be particularly relevant in the case of modified theories of gravity with nonminimal coupling to matter where the matter Lagrangian appears explicitly in the equations of motion of the gravitational and matter fields, such as f(R, L-m) and f(R, T) gravity. In particular, they indicate that, in this context, f(R, L-m) theories may be regarded as a subclass of f(R, T) gravity.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 5