844 research outputs found
Large 2HDM(II) one-loop corrections in leptonic tau decays
The one-loop contributions to the branching ratios for leptonic tau decays
are calculated in the CP conserving 2HDM(II). We found that these one-loop
contributions, involving both neutral and charged Higgs bosons, dominate over
the tree-level H^+ exchange, the latter one being totally negligible for the
decay into electron. The analysis is focused on large tanbeta enhanced
contributions to the considered branching ratios. We derive a simple analytical
expression for the one-loop contribution which holds in this case. We show that
the leptonic branching ratios of tau are complementary to the Higgsstrahlung
processes for h(H) and have a large potential on constraining parameters of the
model. In this work we provide upper limits on Yukawa couplings for both light
h and light A scenarios and we derive new lower limit on mass of M_{H^+} as a
function of tanbeta, which differs significantly from what was considered as
standard constraint based on the tree-level H^{+} exchange only. Interestingly
we obtain also an upper limit on M_{H^+}. For a SM-like h scenario, with heavy
and degenerate additional Higgs bosons, one-loop corrections disappear.Comment: 25 pgs. Figures and their descriptions improved, references adde
Enteric dysbiosis and fecal calprotectin expression in premature infants.
BackgroundPremature infants often develop enteric dysbiosis with a preponderance of Gammaproteobacteria, which has been related to adverse clinical outcomes. We investigated the relationship between increasing fecal Gammaproteobacteria and mucosal inflammation, measured by fecal calprotectin (FC).MethodsStool samples were collected from very-low-birth weight (VLBW) infants at ≤2, 3, and 4 weeks' postnatal age. Fecal microbiome was surveyed using polymerase chain reaction amplification of the V4 region of 16S ribosomal RNA, and FC was measured by enzyme immunoassay.ResultsWe enrolled 45 VLBW infants (gestation 27.9 ± 2.2 weeks, birth weight 1126 ± 208 g) and obtained stool samples at 9.9 ± 3, 20.7 ± 4.1, and 29.4 ± 4.9 days. FC was positively correlated with the genus Klebsiella (r = 0.207, p = 0.034) and its dominant amplicon sequence variant (r = 0.290, p = 0.003), but not with the relative abundance of total Gammaproteobacteria. Klebsiella colonized the gut in two distinct patterns: some infants started with low Klebsiella abundance and gained these bacteria over time, whereas others began with very high Klebsiella abundance.ConclusionIn premature infants, FC correlated with relative abundance of a specific pathobiont, Klebsiella, and not with that of the class Gammaproteobacteria. These findings indicate a need to define dysbiosis at genera or higher levels of resolution
Infrastructure for Detector Research and Development towards the International Linear Collider
The EUDET-project was launched to create an infrastructure for developing and
testing new and advanced detector technologies to be used at a future linear
collider. The aim was to make possible experimentation and analysis of data for
institutes, which otherwise could not be realized due to lack of resources. The
infrastructure comprised an analysis and software network, and instrumentation
infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture
Diffusion in Model Networks as Studied by NMR and Fluorescence Correlation Spectroscopy
We have studied the diffusion of small solvent molecules (octane) and larger hydrophobic dye probes in octane-swollen poly(dimethyl siloxane) linear-chain solutions and end-linked model networks, using pulsed-gradient nuclear magnetic resonance (NMR) and fluorescence correlation spectroscopy (FCS), respectively, focusing on diffusion in the bulk polymer up to the equilibrium degree of swelling of the networks, that is, 4.8 at most. The combination of these results allows for new conclusions on the feasibility of different theories describing probe diffusion in concentrated polymer systems. While octane diffusion shows no cross-link dependence, the larger dyes are increasingly restricted by fixed chemical meshes. The simple Fujita free-volume theory proved most feasible to describe probe diffusion in linear long-chain solutions with realistic parameters, while better fits were obtained assuming a stretched exponential dependence on concentration. Importantly, we have analyzed the cross-link specific effect on probe diffusion independently of any specific model by comparing the best-fit interpolation of the solution data with the diffusion in the networks. The most reasonable description is obtained by assuming that the cross-link effect is additive in the effective friction coefficient of the probes. The concentration dependences as well as the data compared at the equilibrium degrees of swelling indicate that swelling heterogeneities and diffusant shape have a substantial influence on small-molecule diffusion in networks.
Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV
A search for pair-production of supersymmetric particles under the assumption
that R-parity is violated via a dominant LQDbar coupling has been performed
using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV.
The observed candidate events in the data are in agreement with the Standard
Model expectation. This result is translated into lower limits on the masses of
charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for
m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81
GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the
95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure
Charged Higgs Boson Search at the Tevatron Upgrade Using Tau Polarization
We explore the prospect of charged Higgs boson search in top quark decay at
the Tevatron collider upgrade, taking advantage of the opposite states of
polarization resulting from the and decays. Methods of
distinguishing the two contributions in the inclusive 1-prong hadronic decay
channel of are suggested. The resulting signature and discovery limit of
are presented for the Tevatron upgrade as well as the Tevatron
and the Ditevatron options.Comment: 19 pages LaTeX + 6 figures (available on request
The Effects of Fourth Generation on the double Lepton Polarization in B \rar K \ell^+ \ell^- decay
This study investigates the influence of the fourth generation quarks on the
double lepton polarizations in B \rar K \ell^+ \ell^- decay. Taking
|V_{t's}V_{t'b}|\sim \{0.01-0.03\} with phase about 100^\circ, which is
consistent with the b\to s\ell^+\ell^- rate and the B_s mixing parameter Delta
m_{B_s}$, we obtain that the double lepton(muon and tau) polarizations are
quite sensitive to the existence of fourth generation. It can serve as a good
tool to search for new physics effects, precisely, to indirect search for the
fourth generation quarks(t', b').Comment: 30 pages, 27 figure
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