Flux Compactifications were introduced by Strominger as well as De Wit, Smit and Hari Dass as a generalization of conventional Calabi-Yau Compactifications.
In his article Superstrings with Torsion published in Nucl. Phys. B274 (1986) 253 Strominger and on the other hand de Wit, Smit and Hari Dass in their article Residual Supersymmetry for Compactified d=10 Supergravity introduced solutions of Killing equations where the metric included the warp factor and the torsion was non-zero.
This is simpler than it sounds.
General relativity equations give spacetime metrics as solutions.
The supergravity equations, the low energy effective theories corresponding string theories, demand at least two more field apart from the metric. These are the torsion and the dilaton. Plus there can be other bosonic fields apart from the fermionic ones.
So in case of the solutions that we are talking about the innovation is the presence of the torsion as well as the warp factor.
Because of the presence of the warp factor the metric is not a direct product of the internal and external factors when we start talking about compactifications.
Compactifications we have to talk about - after all superstrings prefer to live in ten dimensions while we are determined to live in four.
The fun part is that These new compactifications are generalizations of Calabi-Yau compactifications because these too give us supersymmetric solutions and these possess warp factors.
Of course there were no-go theorems that implied that most of these new compactifications would be equivalent to usual Calabi-Yau compactifications. Yet develoments in non-perturbative string theory and M-Theory suggested that these no-go theorems could be circumvented.
Hence were born the entities that we today call Flux compactifications.
Corresponding M-Theory and F-theory versions were found.
Then came Giddings, Kachru and Polchinski and told us that the flux compactifications can give large hierarchy of scales.
Now that is neat. I mean that is useful. we need hierarchy in physics to solve the hierarchy problem.
In his article Superstrings with Torsion published in Nucl. Phys. B274 (1986) 253 Strominger and on the other hand de Wit, Smit and Hari Dass in their article Residual Supersymmetry for Compactified d=10 Supergravity introduced solutions of Killing equations where the metric included the warp factor and the torsion was non-zero.
This is simpler than it sounds.
General relativity equations give spacetime metrics as solutions.
The supergravity equations, the low energy effective theories corresponding string theories, demand at least two more field apart from the metric. These are the torsion and the dilaton. Plus there can be other bosonic fields apart from the fermionic ones.
So in case of the solutions that we are talking about the innovation is the presence of the torsion as well as the warp factor.
Because of the presence of the warp factor the metric is not a direct product of the internal and external factors when we start talking about compactifications.
Compactifications we have to talk about - after all superstrings prefer to live in ten dimensions while we are determined to live in four.
The fun part is that These new compactifications are generalizations of Calabi-Yau compactifications because these too give us supersymmetric solutions and these possess warp factors.
Of course there were no-go theorems that implied that most of these new compactifications would be equivalent to usual Calabi-Yau compactifications. Yet develoments in non-perturbative string theory and M-Theory suggested that these no-go theorems could be circumvented.
Hence were born the entities that we today call Flux compactifications.
Corresponding M-Theory and F-theory versions were found.
Then came Giddings, Kachru and Polchinski and told us that the flux compactifications can give large hierarchy of scales.
Now that is neat. I mean that is useful. we need hierarchy in physics to solve the hierarchy problem.