25,863 research outputs found
On the Explicit Construction and Statistics of Calabi-Yau Flux Vacua
We explicitly construct and study the statistics of flux vacua for type IIB
string theory on an orientifold of the Calabi-Yau hypersurface
, parametrised by two relevant complex structure moduli. We
solve for these moduli and the dilaton field in terms of the set of integers
defining the 3-form fluxes and examine the distribution of vacua. We compare
our numerical results with the predictions of the Ashok-Douglas density , finding good overall agreement in different regions of moduli
space. The number of vacua are found to scale with the distance in flux space.
Vacua cluster in the region close to the conifold singularity. Large
supersymmetry breaking is more generic but supersymmetric and hierarchical
supersymmetry breaking vacua can also be obtained. In particular, the small
superpotentials and large dilaton VEVs needed to obtain de Sitter space in a
controllable approximation are possible but not generic. We argue that in a
general flux compactification, the rank of the gauge group coming from D3
branes could be statistically preferred to be very small.Comment: 26 pages, 9 figures; v2: references adde
Quasinormal Modes of Charged Scalars around Dilaton Black Holes in 2+1 Dimensions: Exact Frequencies
We have studied the charged scalar perturbation around a dilaton black hole
in 2 +1 dimensions. The wave equations of a massless charged scalar field is
shown to be exactly solvable in terms of hypergeometric functions. The
quasinormal frequencies are computed exactly. The relation between the
quasinormal frequencies and the charge of the black hole, charge of the scalar
and the temperature of the black hole are analyzed. The asymptotic form of the
real part of the quasinormal frequencies are evaluated exactly.Comment: 20 pages and 7 figures, some references are added and some removed.
There are some changes to the text. arXiv admin note: text overlap with
arXiv:hep-th/040716
Dark Radiation in LARGE Volume Models
We consider reheating driven by volume modulus decays in the LARGE Volume
Scenario. Such reheating always generates non-zero dark radiation through the
decays to the axion partner, while the only competitive visible sector decays
are Higgs pairs via the Giudice-Masiero term. In the framework of sequestered
models where the cosmological moduli problem is absent, the simplest model with
a shift-symmetric Higgs sector generates 1.56 < N_{eff} - N_{eff,SM} < 1.74.
For more general cases, the known experimental bounds on N_{eff} strongly
constrain the parameters and matter content of the models.Comment: 6 pages; v2. refs update
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