862 research outputs found
The Private Higgs
We introduce Higgs democracy in the Yukawa sector by constructing a model
with a private Higgs and a dark scalar for each fermion thus addressing the
large hierarchy among fermion masses. The model has interesting implications
for the LHC, while the Standard Model phenomenology is recovered at low
energies. We discuss some phenomenological implications such as FCNC, new
Higgses at the TeV scale and dark matter candidates.Comment: 8 pages, no figures. Version published in Phys. Lett.
Influence of the trap shape on the superfluid-Mott transition in ultracold atomic gases
The coexistence of superfluid and Mott insulator, due to the quadratic
confinement potential in current optical lattice experiments, makes the
accurate detection of the superfluid-Mott transition difficult. Studying
alternative trapping potentials which are experimentally realizable and have a
flatter center, we find that the transition can be better resolved, but at the
cost of a more difficult tuning of the particle filling. When mapping out the
phase diagram using local probes and the local density approximation we find
that the smoother gradient of the parabolic trap is advantageous.Comment: 5 pages, 6 figure
Probing the Majorana nature of TeV-scale radiative seesaw models at collider experiments
A general feature of TeV-scale radiative seesaw models, in which tiny
neutrino masses are generated via loop corrections, is an extended scalar
(Higgs) sector. Another feature is the Majorana nature; e.g., introducing
right-handed neutrinos with TeV-scale Majorana masses under the discrete
symmetry, or otherwise introducing some lepton number violating interactions in
the scalar sector. We study phenomenological aspects of these models at
collider experiments. We find that, while properties of the extended Higgs
sector of these models can be explored to some extent, the Majorana nature of
the models can also be tested directly at the International Linear Collider via
the electron-positron and electron-electron collision experiments.Comment: 19 pages, 7 figures, version published in Physics Letters
The CDF dijet excess from intrinsic quarks
The CDF collaboration reported an excess in the production of two jets in
association with a . We discuss constraints on possible new particle state
interpretations of this excess. The fact of no statistically significant
deviation from the SM expectation for {+dijet} events in CDF data disfavors
the new particle explanation. We show that the nucleon intrinsic strange quarks
provide an important contribution to the boson production in association
with a single top quark production. Such {+t} single top quark production
can contribute to the CDF {+dijet} excess, thus the nucleon intrinsic quarks
can provide a possible explanation to the CDF excess in {+dijet} but not in
{+dijet} events.Comment: 4 latex pages, 1 figure. Version for journal publicatio
Neuro-Behçet: a clinical exercise
Behçet disease is a recurrent systemic vasculitis of unknown etiology, that involves vessels of nearly all sizes and types. Because of this, disease manifestations can occur at many sites throughout the body. Central nervous system (CNS) involvement may be parenchymal or nonparenchymal and has a global prevalence that ranges from 3% to 10%. Main signs of CNS involvement are pyramidal and those resulting from brain stem lesions. Aseptic meningitis, mental changes, sphincter disturbances, pseudobulbar syndrome, and deep sensory abnormalities may be seen. Analysis of cerebrospinal fluid, computed tomography (CT), magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT) and brain angiography offer assistance in the diagnosis. The course of disease can be primary progressive, secondary progressive or have a relapsing-remitting profile.
Boluses of methylprednisolone for three days followed by cyclophosphamide are the treatment of choice.
This papers discusses these aspects of neuro-Behcet on the basis of complex clinical cas
Lepton Private Higgs and the discrete group \Sigma(81)
We use the discrete group \Sigma(81) = (Z_3 x Z_3 x Z_3)\rtimes Z_3 to
explore a particular region of parameter space in the Private Higgs model. In
doing so we suggest a relation among the off-diagonal entries of the neutrino
mass matrix and a possible explanation for the muon magnetic moment anomaly,
a_\mu^{exp}-a_\mu^{SM} ~ 10^{-9}. We predict three new nearly degenerate Higgs
doublets with masses of order ~ 500 GeV to ~ 1 TeV, and three nearly degenerate
SM-singlet TeV-scale neutrinos. The largest scale in the model is ~ 10 TeV, so
there is no severe hierarchy problem. The appendix is devoted to the group
theory of \Sigma(81).Comment: v4: published in Nucl. Phys.
A study of 82 extended HLA haplotypes in HFE-C282Y homozygous hemochromatosis subjects: relationship to the genetic control of CD8+ T-lymphocyte numbers and severity of iron overload
BACKGROUND: It has been recently demonstrated that CD8+ T-lymphocyte numbers are genetically transmitted in association with the MHC class I region. The present study was designed with the objective of narrowing the region associated with the setting of CD8+ T-lymphocyte numbers in a population of C282Y homozygous hemochromatosis subjects, in whom a high prevalence of abnormally low CD8+ T-lymphocyte counts has been described. METHODS: The study includes 43 C282Y homozygous subjects fully characterized both phenotypically and genotypically. Clinical characterization includes measurements of iron parameters at diagnosis (transferrin saturation and serum ferritin), total body iron stores and T-cell immunophenotyping determined by flow cytometry. Genetic characterization includes HLA class I alleles (A, B and C) and four additional microsatellite markers (D6S265, D6S2222, D6S105 and D6S2239) spanning 5 Megabases in the 6p21.3 region. RESULTS: Eighty-two extended C282Y carrying haplotypes were defined. Single-locus analysis revealed that the HLA-A region was associated with CD8+ T-cell numbers. Multivariate analysis showed that the combinations of the most common HLA-A alleles (HLA-A*03, -A*02 and -A*01) were associated with significantly lower numbers of CD8+ T-lymphocytes (0.30 ± 0.14 × 10(6)/ml), in comparison with subjects carrying only one copy of those alleles (0.46 ± 0.19 × 10(6)/ml) and subjects without any copy of those alleles (0.79 ± 0.15 × 10(6)/ml;p = 0.0001). No differences were observed in CD8+ T-cell counts among control subjects carrying the same combinations of HLA-A alleles (0.47 ± 0.14; 0.45 ± 0.21 and 0.41 ± 0.17 × 10(6)/ml, respectively), therefore not supporting a direct effect of HLA specificity but rather an indirect association with a locus close to HLA-A. Multivariate analysis showed that the combination of the most common HLA-A alleles also have an impact on the clinical expression of HH in terms of iron stores, in males(p = 0.0009). CONCLUSION: The present study provides evidence supporting an inextricable link between extended HLA haplotypes, CD8+ T-lymphocyte numbers and severity of iron overload in hereditary hemochromatosis(HH). It gives additional information to better define a candidate region involved in the regulation of CD8+ T-lymphocyte numbers. A new evolutionary hypothesis concerning the inheritance of the phenotype of low CD8+ T-lymphocyte numbers associated with particular ancestral HLA haplotypes carrying the C282Y mutation and its implication on the clinical heterogeneity of HH is discussed
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