19 research outputs found
A scheme with two large extra dimensions confronted with neutrino physics
We investigate a particle physics model in a six-dimensional spacetime, where
two extra dimensions form a torus. Particles with Standard Model charges are
confined by interactions with a scalar field to four four-dimensional branes,
two vortices accommodating ordinary type fermions and two antivortices
accommodating mirror fermions. We investigate the phenomenological implications
of this multibrane structure by confronting the model with neutrino physics
data.Comment: LATEX, 24 pages, 9 figures, minor changes in the tex
The 3-3-1 model with S_4 flavor symmetry
We construct a 3-3-1 model based on family symmetry S_4 responsible for the
neutrino and quark masses. The tribimaximal neutrino mixing and the diagonal
quark mixing have been obtained. The new lepton charge \mathcal{L} related to
the ordinary lepton charge L and a SU(3) charge by L=2/\sqrt{3} T_8+\mathcal{L}
and the lepton parity P_l=(-)^L known as a residual symmetry of L have been
introduced which provide insights in this kind of model. The expected vacuum
alignments resulting in potential minimization can origin from appropriate
violation terms of S_4 and \mathcal{L}. The smallness of seesaw contributions
can be explained from the existence of such terms too. If P_l is not broken by
the vacuum values of the scalar fields, there is no mixing between the exotic
and the ordinary quarks at the tree level.Comment: 20 pages, revised versio
Chromomagnetic Dipole Moment of the Top Quark Revisited
We study the complete one-loop contributions to the chromagnetic dipole
moment of the top quark in the Standard Model, two Higgs doublet
models, topcolor assited technicolor models (TC2), 331 models and extended
models with a single extra dimension. We find that the SM predicts
and that the predictions of the other models are also
consitent with the constraints imposed on by low-energy
precision measurements.Comment: 20 pages, 5 figures, Updat
Two-body decays in the minimal 331 model
The two-body decays of the extra neutral boson Z_2 predicted by the minimal
331 model are analyzed. At the three-level it can decay into standard model
particles as well as exotic quarks and the new gauge bosons predicted by the
model. The decays into a lepton pair are strongly suppressed, with and . In the bosonic
sector, Z_2 would decay mainly into a pair of bilepton gauge bosons, with a
branching ratio below the 0.1 level. The Z_2 boson has thus a leptophobic and
bileptophobic nature and it would decay dominantly into quark pairs. The
anomaly-induced decays and , which occurs
at the one-loop level are studied. It is found that and at most. As for the and decays, with H a relatively light Higgs boson, they
are induced via Z'-Z mixing. It is obtained that
and . We also examine the flavor changing neutral
current decays and , which may have branching
fractions as large as and , respectively, and thus may be of
phenomenological interest.Comment: 14 pages, 3 figures, submitted to Physical Review
Cold Plus Hot Dark Matter Cosmology in the Light of Solar and Atmospheric Neutrino Oscillations
We explore the implications of possible neutrino oscillations, as indicated
by the solar and atmospheric neutrino experiments, for the cold plus hot dark
matter scenario of large scale structure formation. We find that there are
essentially three distinct schemes that can accommodate the oscillation data
and which also allow for dark matter neutrinos. These include (i) three nearly
degenerate (in mass) neutrinos, (ii) non-degenerate masses with in
the eV range, and (iii) nearly degenerate pair (in the eV
range), with the additional possibility that the electron neutrino is
cosmologically significant. The last two schemes invoke a `sterile' neutrino
which is light (< or ~ eV). We discuss the implications of these schemes for
and oscillation, and find
that scheme (ii) in particular, predicts them to be in the observable range. As
far as structure formation is concerned, we compare the one neutrino flavor
case with a variety of other possibilities, including two and three degenerate
neutrino flavors. We show, both analytically and numerically, the effects of
these neutrino mass scenarios on the amplitude of cosmological density
fluctuations. With a Hubble constant of 50 km s Mpc, a spectral
index of unity, and , the two and three flavor
scenarios fit the observational data marginally better than the single flavor
scheme. However, taking account of the uncertainties in these parameters, we
show that it is premature to pick a clear winner.Comment: 1 LaTEX file plus 1 uuencoded Z-compressed tar file with 3 postscript
figure
Arrestin-domain containing protein 1 (Arrdc1) regulates the protein cargo and release of extracellular vesicles
Extracellular vesicles (EVs) are lipid-bilayered vesicles that are released by multiple cell types and contain nucleic acids and proteins. Very little is known about how the cargo is packaged into EVs. Ubiquitination of proteins is a key posttranslational modification that regulates protein stability and trafficking to subcellular compartments including EVs. Recently, arrestin-domain containing protein 1 (Arrdc1), an adaptor for the Nedd4 family of ubiquitin ligases, has been implicated in the release of ectosomes, a subtype of EV that buds from the plasma membrane. However, it is currently unknown whether Arrdc1 can regulate the release of exosomes, a class of EVs that are derived endocytically. Furthermore, it is unclear whether Arrdc1 can regulate the sorting of protein cargo into the EVs. Exosomes and ectosomes are isolated from mouse embryonic fibroblasts isolated from wild type and Arrdc1-deficient (Arrdc1-/- ) mice. Nanoparticle tracking analysis-based EV quantitation shows that Arrdc1 regulates the release of both exosomes and ectosomes. Proteomic analysis highlights the change in protein cargo in EVs upon deletion of Arrdc1. Functional enrichment analysis reveals the enrichment of mitochondrial proteins in ectosomes, while proteins implicated in apoptotic cleavage of cell adhesion proteins and formation of cornified envelope are significantly depleted in exosomes upon knockout of Arrdc1.Sushma Anand, Natalie Foot, Ching-Seng Ang, Kelly M. Gembus, Shivakumar Keerthikumar, Christopher G. Adda, Suresh Mathivanan and Sharad Kuma