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oai:docta.ucm.es:20.500.14352/335702023-08-25T16:27:26Zcom_20.500.14352_14col_20.500.14352_15

Isotropy theorem for cosmological Yang-Mills theories López Maroto, Antonio Ruiz Cembranos, José Alberto Núñez Jareño, S. J. 53 Gauge-Flation Inflation Universo Fields Física (Física) 22 Física © 2013 American Physical Society. We thank Marco Peloso and Jose Beltrán Jiménez for useful comments. This work has been supported by MICINN (Spain) project numbers FIS2011-23000, FPA2011-27853-01, and Consolider-Ingenio MULTIDARK CSD2009-00064. We consider homogeneous non-Abelian vector fields with general potential terms in an expanding universe. We find a mechanical analogy with a system of N interacting particles (with N the dimension of the gauge group) moving in three dimensions under the action of a central potential. In the case of bounded and rapid evolution compared to the rate of expansion, we show by making use of a generalization of the virial theorem that for an arbitrary potential and polarization pattern, the average energy-momentum tensor is always diagonal and isotropic despite the intrinsic anisotropic evolution of the vector field. We consider also the case in which a gauge-fixing term is introduced in the action and show that the average equation of state does not depend on such a term. Finally, we extend the results to arbitrary background geometries and show that the average energy-momentum tensor of a rapidly evolving Yang-Mills field is always isotropic and has the perfect fluid form for any locally inertial observer. MICINN (Spain) Depto. de Física Teórica Fac. de Ciencias Físicas TRUE pub 2023-06-19T13:24:25Z 2023-06-19T13:24:25Z 2013-02-13 journal article https://hdl.handle.net/20.500.14352/33570 1550-7998 10.1103/PhysRevD.87.043523 eng FIS2011-23000 FPA2011-27853-01 CSD2009-00064. Consolider-Ingenio MULTIDARK open access application/pdf American Physical Society