227 research outputs found
Realistic Type IIB Supersymmetric Minkowski Flux Vacua
We show that there exist supersymmetric Minkowski vacua on Type IIB toroidal
orientifold with general flux compactifications where the RR tadpole
cancellation conditions can be relaxed elegantly. Then we present a realistic
Pati-Salam like model. At the string scale, the gauge symmetry can be broken
down to the Standard Model (SM) gauge symmetry, the gauge coupling unification
can be achieved naturally, and all the extra chiral exotic particles can be
decoupled so that we have the supersymmetric SMs with/without SM singlet(s)
below the string scale. The observed SM fermion masses and mixings can also be
obtained. In addition, the unified gauge coupling, the dilaton, the complex
structure moduli, the real parts of the K\"ahler moduli and the sum of the
imaginary parts of the K\"ahler moduli can be determined as functions of the
four-dimensional dilaton and fluxes, and can be estimated as well.Comment: RevTex4, 4 pages, 3 table
The Minimal GUT with Inflaton and Dark Matter Unification
Giving up the solutions to the fine-tuning problems, we propose the
non-supersymmetric flipped model based on the minimal
particle content principle, which can be constructed from the four-dimensional
models, five-dimensional orbifold models, and local F-theory
models. To achieve gauge coupling unification, we introduce one pair
of vector-like fermions, which form complete
representation. Proton lifetime is around years, neutrino
masses and mixing can be explained via seesaw mechanism, baryon asymmetry can
be generated via leptogenesis, and vacuum stability problem can be solved as
well. In particular, we propose that inflaton and dark matter particle can be
unified to a real scalar field with symmetry, which is not an axion and
does not have the non-minimal coupling to gravity. Such kind of scenarios can
be applied to the generic scalar dark matter models. Also, we find that the
vector-like particle corrections to the masses can be about 6.6%, while
their corrections to the and masses are negligible.Comment: 5 pages, 4 figures;V2: published versio
Yukawa Corrections from Four-Point Functions in Intersecting D6-Brane Models
We discuss corrections to the Yukawa matrices of the Standard Model (SM)
fermions in intersecting D-brane models due to four-point interactions.
Recently, an intersecting D-brane model has been found where it is possible to
obtain correct masses and mixings for all quarks as well as the tau lepton.
However, the masses for the first two charged leptons come close to the right
values but are not quite correct. Since the electron and muon are quite light,
it is likely that there are additional corrections to their masses which cannot
be neglected. With this in mind, we consider contributions to the SM fermion
mass matrices from four-point interactions. In an explicit model, we show that
it is indeed possible to obtain the SM fermion masses and mixings which are a
better match to those resulting from experimental data extrapolated at the
unification scale when these corrections are included. These corrections may
have broader application to other models.Comment: 24 pages, 4 figure
A Realistic World from Intersecting D6-Branes
We briefly describe a three-family intersecting D6-brane model in Type IIA
theory on the T^6/(Z_2 x Z_2) orientifold with a realistic phenomenology. In
this model, the gauge symmetry can be broken down to the Standard Model (SM)
gauge symmetry close to the string scale, and the gauge coupling unification
can be achieved. We calculate the supersymmetry breaking soft terms, and the
corresponding low energy supersymmetric particle spectrum, which may be tested
at the Large Hadron Collider (LHC). The observed dark matter density may also
be generated. Finally, we can explain the SM quark masses and CKM mixings, and
the tau lepton mass. The neutrino masses and mixings may be generated via the
seesaw mechanism as well.Comment: RevTex4, 4 pages, 4 table
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