2019-08-23T08:28:17Z
http://digital.csic.es/dspace-oai/request
oai:digital.csic.es:10261/112146
2016-02-18T03:12:14Z
com_10261_14181
com_10261_4
col_10261_14182
Magueijo, J.
Rodríguez-Vázquez, M.
Westman, H.
Zlosnik, T.
2015-03-11T09:47:01Z
2015-03-11T09:47:01Z
2014-03-31
Physical Review D - Particles, Fields, Gravitation and Cosmology 89: 063542 (2014)
http://hdl.handle.net/10261/112146
10.1103/PhysRevD.89.063542
We investigate the possibility for classical metric signature change in a straightforward generalization of the first-order formulation of gravity, dubbed >Cartan gravity.> The mathematical structure of this theory mimics the electroweak theory in that the basic ingredients are an SO(1,4) Yang-Mills gauge field Aabμ and a symmetry breaking Higgs field Va, with no metric or affine structure of spacetime presupposed. However, these structures can be recovered, with the predictions of general relativity exactly reproduced, whenever the Higgs field breaking the symmetry to SO(1,3) is forced to have a constant (positive) norm VaVa. This restriction is usually imposed >by hand,> but in analogy with the electroweak theory we promote the gravitational Higgs field Va to a genuine dynamical field, subject to nontrivial equations of motion. Even though we limit ourselves to actions polynomial in these variables, we discover a rich phenomenology. Most notably we derive classical cosmological solutions exhibiting a smooth transition between Euclidean and Lorentzian signature in the four-metric. These solutions are nonsingular and arise whenever the SO(1,4) norm of the Higgs field changes sign; i.e. the signature of the metric of spacetime is determined dynamically by the gravitational Higgs field. It is possible to find a plethora of such solutions and in some of them this dramatic behavior is confined to the early Universe, with the theory asymptotically tending to Einstein gravity at late times. Curiously the theory can also naturally embody a well-known dark energy model: Peebles-Ratra quintessence. © 2014 American Physical Society.
eng
openAccess
Cosmological signature change in Cartan gravity with dynamical symmetry breaking
Artículo