7 research outputs found
Entropy function for rotating extremal black holes in very special geometry
We use the relation between extremal black hole solutions in five- and in
four-dimensional N=2 supergravity theories with cubic prepotentials to define
the entropy function for extremal black holes with one angular momentum in five
dimensions. We construct two types of solutions to the associated attractor
equations.Comment: 15 pages, minor change
First-order flow equations for extremal black holes in very special geometry
We construct interpolating solutions describing single-center static extremal
non-supersymmetric black holes in four-dimensional N=2 supergravity theories
with cubic prepotentials. To this end, we derive and solve first-order flow
equations for rotating electrically charged extremal black holes in a Taub-NUT
geometry in five dimensions. We then use the connection between five- and
four-dimensional extremal black holes to obtain four-dimensional flow equations
and we give the corresponding solutions.Comment: 21 pages. v2: Summary section adde
The everpresent eta-problem: knowledge of all hidden sectors required
We argue that the eta-problem in supergravity inflation cannot be solved
without knowledge of the ground state of hidden sectors that are
gravitationally coupled to the inflaton. If the hidden sector breaks
supersymmetry independently, its fields cannot be stabilized during
cosmological evolution of the inflaton. We show that both the subsequent
dynamical mixing between sectors as well as the lightest mass of the hidden
sector are set by the scale of supersymmetry breaking in the hidden sector. The
true cosmological eta-parameter arises from a linear combination of the
lightest mode of the hidden sector with the inflaton. Generically, either the
true eta deviates considerably from the na\"ive eta implied by the inflaton
sector alone, or one has to consider a multifield model. Only if the lightest
mass in the hidden sector is much larger than the inflaton mass and if the
inflaton mass is much larger than the scale of hidden sector supersymmetry
breaking, is the effect of the hidden sector on the slow-roll dynamics of the
inflaton negligible.Comment: 27 pages, 6 figures; v2, published version, minor adjustments to the
introduction, minor corrections to section 2.2 for improved clarity,
references adde