THESIS
2014
vii, 43 pages : illustrations ; 30 cm
Abstract
An unexpectedly tiny cosmological constant (i.e. the vacuum energy density)
Λ = 10
^{-122} M
_{P}^{4} has been observed since the 1990s. This thesis examine the
statistical interpretation of the cosmological constant problem in supergravity
models. The racetrack model in Type IIB string theory is studied in the presence
of leading α-correction in flux compactification. We show that a class of de-Sitter
vacua is generic under the approximation of large volume compactification. The
absence of constraint on the compactified volume for the meta-stable de-Sitter
vacua in this model leads to a controllable α' correction. We find that the median
Λ
_{50%} is exponentially suppressed by the compactified volume and the probability
distribution function of Λ diverges as Λ approaches 0
^{+}. We then study th...[
Read more ]
An unexpectedly tiny cosmological constant (i.e. the vacuum energy density)
Λ = 10
^{-122} M
_{P}^{4} has been observed since the 1990s. This thesis examine the
statistical interpretation of the cosmological constant problem in supergravity
models. The racetrack model in Type IIB string theory is studied in the presence
of leading α-correction in flux compactification. We show that a class of de-Sitter
vacua is generic under the approximation of large volume compactification. The
absence of constraint on the compactified volume for the meta-stable de-Sitter
vacua in this model leads to a controllable α' correction. We find that the median
Λ
_{50%} is exponentially suppressed by the compactified volume and the probability
distribution function of Λ diverges as Λ approaches 0
^{+}. We then study the large
volume scenario model and show that the scale of gravitino mass can be splitted
from that of the cosmological constant. The probability distribution of Λ in this
model where SUSY can be broken or remain unbroken peaks at Λ = 0
^{-} but anti
de-Sitter vacua is generic in this model in the absence of fine tuned uplifting.
Post a Comment