414 research outputs found
Higgs sector and R-parity breaking couplings in models with broken U(1)_B-L gauge symmetry
Four different supersymmetric models based on SU(2)_L X U(1)_R X U(1)_B-L and
SU(2)_L X SU(2)_R X U(1)_B-L gauge symmetry groups are studied. U(1)_B-L
symmetry is broken spontaneously by a vacuum expectation value (VEV) of a
sneutrino field. The right-handed gauge bosons may obtain their mass solely by
sneutrino VEV. The physical charged lepton and neutrino are mixtures of
gauginos, higgsinos and lepton interaction eigenstates. Explicit formulae for
masses and mixings in the physical lepton fields are found. The spontaneous
symmetry breaking mechanism fixes the trilinear R-parity breaking couplings.
Only some special R-parity breaking trilinear couplings are allowed. There is a
potentially large trilinear lepton number breaking coupling - which is unique
to left-right models - that is proportional to the SU(2)_R gauge coupling g_R.
The couplings are parametrized by few mixing angles, making the spontaneous
R-parity breaking a natural ``unification framework'' for R-parity breaking
couplings in SUSYLR models.Comment: 19 pages, no figures, uses REVTeX. To be published in PR
b -> s gamma in the left-right supersymmetric model
The rare decay is studied in the left-right supersymmetric
model. We give explicit expressions for all the amplitudes associated with the
supersymmetric contributions coming from gluinos, charginos and neutralinos in
the model to one-loop level. The branching ratio is enhanced significantly
compared to the standard model and minimal supersymmetric standard model values
by contributions from the right-handed gaugino and squark sector. We give
numerical results coming from the leading order contributions. If the only
source of flavor violation comes from the CKM matrix, we constrain the scalar
fermion-gaugino sector. If intergenerational mixings are allowed in the squark
mass matrix, we constrain such supersymmetric sources of flavor violation. The
decay sets constraints on the parameters of the model and
provides distinguishing signs from other supersymmetric scenarios.Comment: 12 figure
Special geometry of Euclidean supersymmetry II: hypermultiplets and the c-map
We construct two new versions of the c-map which allow us to obtain the
target manifolds of hypermultiplets in Euclidean theories with rigid N =2
supersymmetry. While the Minkowskian para-c-map is obtained by dimensional
reduction of the Minkowskian vector multiplet lagrangian over time, the
Euclidean para-c-map corresponds to the dimensional reduction of the Euclidean
vector multiplet lagrangian. In both cases the resulting hypermultiplet target
spaces are para-hyper-Kahler manifolds. We review and prove the relevant
results of para-complex and para-hypercomplex geometry. In particular, we give
a second, purely geometrical construction of both c-maps, by proving that the
cotangent bundle N=T^*M of any affine special (para-)Kahler manifold M is
para-hyper-Kahler.Comment: 36 pages, 1 figur
Luteinizing hormone and different genetic variants, as indicators of frailty in healthy elderly men
We investigated the possible clinical correlates between the serum LH
concentration and characteristics of frailty and determined the presence
and concentration of a genetic LH variant in an independently living
population of elderly men. After exclusion of subjects with severe
mobility problems and signs of dementia, 403 healthy men (aged 73-94 yr)
were randomly selected from a population-based sample. Total testosterone
(T), sex hormone-binding globulin (SHBG), and leptin were determined by
RIA. Non-SHBG-bound T was calculated. LH and the presence of the genetic
LH variant were measured using immunofluorometric assays. The
characteristics of frailty were leg extensor strength using dynamometry,
bone mineral density of total body and proximal femur, and body
composition, including lean mass and fat mass, measured by dual energy
x-ray absorptiometry. Disability was further assessed by the Modified
Health Assessment Questionnaire and by a measure of physical performance.
LH significantly increased with age and inversely correlated with T and
non-SHBG-bound T. LH was inversely related to muscle strength and lean
mass, and both relations were independent of T. LH was positively related
to self-reported disability (Modified Health Assessment Questionnaire);
12.5% of the study population was heterozygous for the LH variant allele.
T levels and the degree of frailty were not different in the wild-type LH
group compared with the heterozygote LH variant group. A significant
positive relation between LH and fat mass as well as leptin was only
present in the heterozygote LH variant group. In conclusion, serum LH
levels increases with age in independently living elderly men and
correlates inversely with a variety of indicators of frailty. The observed
relation between LH and frailty, independent of T, suggests that LH
reflects serum androgen activity in a different way than T, possibly
reflecting more closely the combined feedback effect of estrogen and
androgen. A difference in biological response between the two LH forms is
suggested, as a difference exists in the relation between LH and fat mass,
respectively, and leptin in the heterozygote LH variant subjects vs. the
wild-type LH subjects
Embodied Discourses of Literacy in the Lives of Two Preservice Teachers
This study examines the emerging teacher literacy identities of Ian and A.J., two preservice teachers in a graduate teacher education program in the United States. Using a poststructural feminisms theoretical framework, the study illustrates the embodiment of literacy pedagogy discourses in relation to the literacy courses’ discourse of comprehensive literacy and the literacy biographical discourses of Ian and A.J. The results of this study indicate the need to deconstruct how the discourse of comprehensive literacy limits how we, as literacy teacher educators, position, hear and respond to our preservice teachers and suggests the need for differentiation in our teacher education literacy courses
Crystallographic and Magnetic Structure of the Perovskite-Type Compound BaFeO2.5: unrivaled complexity in oxygen vacancy ordering
We report here on the characterization of the vacancy-ordered perovskite-type structure of BaFeO2.5 by means of combined Rietveld analysis of powder X-ray and neutron diffraction data. The compound crystallizes in the monoclinic space group P2(1)/c [a = 6.9753(1) Å, b = 11.7281(2) Å, c = 23.4507(4) Å, β = 98.813(1)°, and Z = 28] containing seven crystallographically different iron atoms. The coordination scheme is determined to be Ba7(FeO4/2)1(FeO3/2O1/1)3(FeO5/2)2(FeO6/2)1 = Ba7Fe([6])1Fe([5])2Fe([4])4O17.5 and is in agreement with the (57)Fe Mössbauer spectra and density functional theory based calculations. To our knowledge, the structure of BaFeO2.5 is the most complicated perovskite-type superstructure reported so far (largest primitive cell, number of ABX2.5 units per unit cell, and number of different crystallographic sites). The magnetic structure was determined from the powder neutron diffraction data and can be understood in terms of "G-type" antiferromagnetic ordering between connected iron-containing polyhedra, in agreement with field-sweep and zero-field-cooled/field-cooled measurements
Delta M_K and epsilon_K in the left-right supersymmetric model
We perform a complete analysis of processes in the kaon system
and evaluate and in the left-right supersymmetric
model. We include analytic expressions for the contributions of gluinos,
neutralinos and charginos. We obtain general constraints on off-diagonal mass
terms between the first two generations of both down-type and up-type squarks.
In the down-squark sector, we compare the results with gluino-only estimates.
In the up-squark sector, we find a complete set of bounds on all combinations
of chirality conserving or chirality flipping parameters. Finally, we comment
on the size of the bounds obtained by imposing left-right symmetry in the
squark sector.Comment: 22 pages, 1 figure and 4 table
Characterization of neutrino signals with radiopulses in dense media through the LPM effect
We discuss the possibilities of detecting radio pulses from high energy
showers in ice, such as those produced by PeV and EeV neutrino interactions. It
is shown that the rich radiation pattern structure in the 100 MHz to few GHz
allows the separation of electromagnetic showers induced by photons or
electrons above 100 PeV from those induced by hadrons. This opens up the
possibility of measuring the energy fraction transmitted to the electron in a
charged current electron neutrino interaction with adequate sampling of the
angular distribution of the signal. The radio technique has the potential to
complement conventional high energy neutrino detectors with flavor information.Comment: 5 pages, 4 ps figures. Submitted to Phys. Rev. Let
Targeted Chromatin Capture (T2C): A novel high resolution high throughput method to detect genomic interactions and regulatory elements.
Background: Significant efforts have recently been put into the investigation of the spatial organization and the chromatin-interaction networks of genomes. Chromosome conformation capture (3C) technology and its derivatives are important tools used in this effort. However, many of these have limitations, such as being limited to one viewpoint, expensive with moderate to low resolution, and/or requiring a large sequencing effort. Techniques like Hi-C provide a genome-wide analysis. However, it requires massive sequencing effort with considerable costs. Here we describe a new technique termed Targeted Chromatin Capture (T2C), to interrogate large selected regions of the genome. T2C provides an unbiased view of the spatial organization of selected loci at superior resolution (single restriction fragment resolution, from 2 to 6 kbp) at much lower costs than Hi-C due to the lower sequencing effort. Results: We applied T2C on well-known model regions, the mouse β-globin locus and the human H19/IGF2 locus. In both cases we identified all known chromatin interactions. Furthermore, we compared the human H19/IGF2 locus data obtained from different chromatin conformation capturing methods with T2C data. We observed the same compartmentalization of the locus, but at a much higher resolution (single restriction fragments vs. the common 40 kbp bins) and higher coverage. Moreover, we compared the β-globin locus in two different biological samples (mouse primary erythroid cells and mouse fetal brain), where it is either actively transcribed or not, to identify possible transcriptional dependent interactions. We identified the known interactions in the β-globin locus and the same topological domains in both mouse primary erythroid cells and in mouse fetal brain with the latter having fewer interactions probably due to the inactivity of the locus. Furthermore, we show that interactions due to the important chromatin proteins, Ldb1 and Ctcf, in both tissues can be analyzed easily to reveal their role on transcriptional interactions and genome folding. Conclusions: T2C is an efficient, easy, and affordable with high (restriction fragment) resolution tool to address both genome compartmentalization and chromatin-interaction networks for specific genomic regions at high resolution for both clinical and non-clinical research
Left-right symmetry in 5D and neutrino mass in TeV scale gravity models
We construct a left-right symmetric model based on the gauge group
in five dimensions where both the
gauge bosons and fermions reside in all five dimensions. The orbifold boundary
conditions are used not only to break the gauge symmetry down to but also to ``project'' the right handed neutrino out
of the zero mode part of the spectrum, providing a new way to understand the
small neutrino masses without adding (singlet) bulk neutrinos. This formulation
of the left-right model has also two new features: (i) it avoids most existing
phenomenological bounds on the scale of the right handed boson allowing
for the possibility that the right handed gauge bosons could have masses under
a TeV, and (ii) it predicts a stable lepton with mass of order of the inverse
radius of the fifth dimension.Comment: 20 pages; some new materials and references adde
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