Progress toward a theory of supergravity

Graded Poisson-sigma models and dilaton-deformed 2D supergravity algebra

“…Obviously the nonlinear gauge symmetry (1.3) does not lend itself to an appropriate starting point for this task, the conditions for supergravity being not inherent in general gPSM theories: Any strategy must -in some sense-contain the restriction known in supergravity models from superspace or from a gauge-theoretic approach that, in the limit of flat space-time of the bosonic geometry, the fermionic sector must reduce to rigid supersymmetry [8][9][10][11]42]. In a generic PSM the bosonic potential need not have any flat space-time limit and thus a generalization covering also those geometries is necessary.…”

“…They include effective theories of direct physical interest, like reduced d-dimensional Einstein theories and the extensions thereof (Einstein-deSitter, Jordan-Brans-Dicke theories [1][2][3][4][5]), but also theories suggested by stringy arguments [6] 1 . On the other hand, supersymmetric extensions of gravity [8][9][10][11] are believed to be a crucial ingredient for a consistent solution of the problem how to quantize gravity in the framework of string/brane theory [12][13][14].…”

“…The Jackiw-Teitelboim model [32][33][34][35][36] corresponds to 8) and the bosonic part of the simplest non-trivial 2d supergravity model of Howe [37] -after the correct identification of the dilaton with one of the components of the superfield [38]becomes…”

Backreaction mechanism in multifluid and extended cosmologies

“…The EFE for these theories are given by 14) where the quintessence field energy-momentum tensor and the field equation of motion become 15) and 16) respectively. Thus, whenever the potential is flat enough so that the field is slowly rolling down, the scalar field can drive a period of accelerated expansion.…”

“…Both points of view are mathematically equivalent since geometrical modifications can be interpreted as curvature fluids and hence interpreted as DE contributions. Some examples of this include minimally-coupled models of scalar fields known as quintessence [5] or more general K-essence models [6], Lovelock theories [7], Gauss-Bonnet theories [8], scalar-tensor theories like Brans-Dicke [9][10][11] or more general models [12], vector-tensor theories [13], gravitational theories derived from extra dimensional models [14]; supergravity models [15], disformal theories [16] or models with either quantumgravity-induced violation or deformation of Lorentz symmetry and models of gravity breaking CPT [17]. In fact, the so-called f (R) theories [18], where the usual Einstein-Hilbert gravitational action is replaced by a more general f (R) term, can be understood as a kind of scalar-tensor theory.…”