bianchi cosmologies
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2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Ladislav Hlavatý ◽  
Ivo Petr

AbstractIn previous papers we have presented many purely bosonic solutions of Generalized Supergravity Equations obtained by Poisson–Lie T-duality and plurality of flat and Bianchi cosmologies. In this paper we focus on their compactifications and identify solutions that can be interpreted as T-folds. To recognize T-folds we adopt the language of Double Field Theory and discuss how Poisson–Lie T-duality/plurality fits into this framework. As a special case we confirm that all non-Abelian T-duals can be compactified as T-folds.





2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Ladislav Hlavatý ◽  
Ivo Petr

Abstract We investigate a special class of Poisson–Lie T-plurality transformations of Bianchi cosmologies invariant with respect to non-semisimple Bianchi groups. For six-dimensional semi-Abelian Manin triples $$\mathfrak {b}\bowtie \mathfrak {a}$$b⋈a containing Bianchi algebras $$\mathfrak {b}$$b we identify general forms of Poisson–Lie identities and dualities. We show that these can be decomposed into simple factors, namely automorphisms of Manin triples, B-shifts, $$\beta $$β-shifts, and “full” or “factorized” dualities. Further, we study effects of these transformations and utilize the decompositions to obtain new backgrounds which, supported by corresponding dilatons, satisfy Generalized Supergravity Equations.



2018 ◽  
Vol 35 (9) ◽  
pp. 095004 ◽  
Author(s):  
Ben David Normann ◽  
Sigbjørn Hervik ◽  
Angelo Ricciardone ◽  
Mikjel Thorsrud


2011 ◽  
Vol 20 (11) ◽  
pp. 2125-2138 ◽  
Author(s):  
FEI-HUNG HO ◽  
JAMES M. NESTER

We are investigating the dynamics of a new Poincaré gauge theory of gravity model, which has cross coupling between the spin-0+ and spin-0- modes. To this end we here consider a very appropriate situation — homogeneous-isotropic cosmologies — which is relatively simple, and yet all the modes have nontrivial dynamics which reveals physically interesting and possibly observable results. More specifically we consider manifestly isotropic Bianchi class A cosmologies; for this case we find an effective Lagrangian and Hamiltonian for the dynamical system. The Lagrange equations for these models lead to a set of first-order equations that are compatible with those found for the FLRW models and provide a foundation for further investigations. Typical numerical evolution of these equations shows the expected effects of the cross parity coupling.





2010 ◽  
Vol 229 ◽  
pp. 012076 ◽  
Author(s):  
D L Cáceres ◽  
L Castañeda ◽  
J M Tejeiro


2007 ◽  
Vol 22 (25n28) ◽  
pp. 2039-2046 ◽  
Author(s):  
CHIANG-MEI CHEN ◽  
JIAN-LIANG LIU ◽  
JAMES M. NESTER

First we briefly review our covariant Hamiltonian approach to quasi-local energy, noting that the Hamiltonian-boundary-term quasi-local energy expressions depend on the chosen boundary conditions and reference configuration. Then we present the quasi-local energy values resulting from the formalism applied to homogeneous Bianchi cosmologies. Finally we consider the quasi-local energies of the FRW cosmologies. Our results do not agree with certain widely accepted quasi-local criteria.



2006 ◽  
Vol 23 (23) ◽  
pp. 6585-6597 ◽  
Author(s):  
Deon Solomons ◽  
Peter K S Dunsby ◽  
George F R Ellis
Keyword(s):  


2006 ◽  
Vol 47 (10) ◽  
pp. 102502 ◽  
Author(s):  
T. Christodoulakis ◽  
Petros A. Terzis


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