253 research outputs found
Canonical Seesaw Mechanism in Electro-Weak SU(4)L x U(1)Y Models
In this paper we prove that the canonical seesaw mechanism can naturally be
implemented in a particular class of electro-weak SU(4)L x U(1)Y gauge models.
The resulting neutrino mass spectrum is determined by just tuning a unique free
parameter 'a' within the algebraical method of solving gauge models with high
symmetries. All the Standard Model phenomenology is preserved, being unaffected
by the new physics occuring at a high breaking scale m ~ 10^11GeV.Comment: 12 pages, 1 Table, no figure
model for electroweak unification and sterile neutrinos
Some of basic problems in neutrino physics such as new energy scales, the
enormous gap between neutrino masses and the lightest charged fermion mass,
possible existance of sterile neutrinos in eV mass range are studied in the
local gauge group for electroweak unification, which
does not contain fermions with exotic electric charges. It is shown that
neutrino mass spectrum can be decoupled from that of the other fermions.
Further normal seesaw mechanism for neutrinos, with right handed neutrino
Majorana masses to be of order as well a new eV-scale
can be accomodated. The eV-scale seesaw may manifest itself in experiments like
Liquid Scintilation Neutrino Detector (LSND) and MiniBooNE (MB) experimental
results and future neutrino experiments.Comment: 13 page
Boson mass spectrum in model with exotic electric charges
The boson mass spectrum of the electro-weak \textbf{} model with exotic electric charges is investigated by using the
algebraical approach supplied by the method of exactly solving gauge models
with high symmetries. Our approach predicts for the boson sector a
one-parameter mass scale to be tuned in order to match the data obtained at
LHC, LEP, CDF.Comment: 12 pages, 1 Table with numerical estimates and 1 Figure added,
mistaken results correcte
Calabi-Yau 3-folds from 2-folds
We consider type IIA string theory on a Calabi-Yau 2-fold with D6-branes
wrapping 2-cycles in the 2-fold. We find a complete set of conditions on the
supergravity solution for any given wrapped brane configuration in terms of
SU(2) structures. We reduce the problem of finding a supergravity solution for
the wrapped branes to finding a harmonic function on RCY. We then
lift this solution to 11-dimensions as a product of R and a
Calabi-Yau 3-fold. We show how the metric on the 3-fold is determined in terms
of the wrapped brane solution. We write down the distinguished (3,0) form and
the K{\"a}hler form of the 3-fold in terms of structures defined on the base
2-d complex manifold. We discuss the topology of the 3-fold in terms of the
D6-branes and the underlying 2-fold. We show that in addition to the
non-trivial cycles inherited from the underlying 2-fold there are new
2-cycles. We construct closed (1,1) forms corresponding to these new cycles. We
also display some explicit examples. One of our examples is that of D6-branes
wrapping the 2-cycle in an A ALE space, the resulting 3-fold has
, where is the number of D6-branes.Comment: 30 page
Supergravity Solution of Intersecting Branes and AdS/CFT with Flavor
We construct the supergravity solution for fully localized D2/D6
intersection. The near horizon limit of this solution is the supergravity dual
of supersymmetric Yang-Mills theory in 2+1 dimensions with flavor. We use this
solution to formulate mirror symmetry of 2+1 dimensional gauge theories in the
language of AdS/CFT correspondence. We also construct the supergravity dual of
a non-commutative gauge theory with fundamental matter.Comment: 17 Pages, 2 figures, references added. Minor corrections to eqs (5.3)
and (5.4
A note on bosonic open strings in constant B field
We sketch the main steps of old covariant quantization of bosonic open
strings in a constant field background. We comment on its space-time
symmetries and the induced effective metric. The low-energy spectrum is
evaluated and the appearance of a new non-commutative gauge symmetry is
addressed.Comment: 13 pages, Latex, important comments added, to appear in PR
That's a wrap!
Calibration technology provides us with a fast and elegant way to find the
supergravity solutions for BPS wrapped M-branes. Its true potential had however
remained untapped due to the absence of a classification of calibrations in
spacetimes with non-trivial flux. The applications of this method were thus
limited in practise to M-branes wrapping Kahler calibrated cycles. In this
paper, we catagorize a type of generalised calibrations which exist in
supergravity backgrounds and contain Kahler calibrations as a sub-class. This
broadens the arena of brane configurations whose supergravity solutions are
accessible through the calibration 'short-cut' method.Comment: 19 pages, typos correcte
SU_L(4) x U(1) model for electroweak unification
After some general remarks about SU_L(4) electroweak unification, the model
is extended to SU_L(4)xU_X(1) to accomodate fractionally charged quarks. The
unification scale is expected to be in TeV region. A right-handed Majorana
neutrino along with known lepton are put in the fundamental representation of
SU_L(4) with Y_X=0. The see-saw mechanism for neutrino masses and flavor mixing
in neutrino sector is a natural feature of the model. The lepton number
violating processes can occure through dilepton gauge bosons contained in the
model.Comment: RevTeX, 9 pages, no figure: replaced with revised versio
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