744 research outputs found
Chiral Dynamics and S-wave Contributions in Semileptonic B decays
The flavor-changing neutral current process is beneficial to
testing the standard model and hunting for new physics scenarios. In exclusive
decay modes like , the S-wave effects may not be
negligible and thus have to be reliably estimated. Using the scalar form
factors derived from dispersion relations in two channels and matched to Chiral
Perturbation Theory, we investigate the S-wave contributions in , with the invariant mass lying in the vicinity of the
mass of , and the with .
We find that the S-wave will modify differential decay widths by about 10% in
the process of and about 5% in . A forward-backward asymmetry for the charged kaon in the final state
arises from the interference between the S-wave and P-wave contributions. The
measurement of this asymmetry offers a new way to determine the variation of
the S-wave phase versus the invariant mass.Comment: 26 pages, 10 figure
The Optical Potential on the Lattice
The extraction of hadron-hadron scattering parameters from lattice data by
using the L\"uscher approach becomes increasingly complicated in the presence
of inelastic channels. We propose a method for the direct extraction of the
complex hadron-hadron optical potential on the lattice, which does not require
the use of the multi-channel L\"uscher formalism. Moreover, this method is
applicable without modifications if some inelastic channels contain three or
more particles.Comment: 26 pages, 12 figure
High-precision measurement of the half-life of Ga
The beta-decay half-life of 62Ga has been studied with high precision using
on-line mass separated samples. The decay of 62Ga which is dominated by a 0+ to
0+ transition to the ground state of 62Zn yields a half-life of T_{1/2} =
116.19(4) ms. This result is more precise than any previous measurement by
about a factor of four or more. The present value is in agreement with older
literature values, but slightly disagrees with a recent measurement. We
determine an error weighted average value of all experimental half-lives of
116.18(4) ms.Comment: 9 pages, 5 figures, accepted for publication in PR
Assessment of pulmonary antibodies with induced sputum and bronchoalveolar lavage induced by nasal vaccination against Pseudomonas aeruginosa: a clinical phase I/II study
<p>Abstract</p> <p>Background</p> <p>Vaccination against <it>Pseudomonas aeruginosa </it>is a desirable albeit challenging strategy for prevention of airway infection in patients with cystic fibrosis. We assessed the immunogenicity of a nasal vaccine based on the outer membrane proteins F and I from <it>Pseudomonas aeruginosa </it>in the lower airways in a phase I/II clinical trial.</p> <p>Methods</p> <p>N = 12 healthy volunteers received 2 nasal vaccinations with an OprF-OprI gel as a primary and a systemic (n = 6) or a nasal booster vaccination (n = 6). Antibodies were assessed in induced sputum (IS), bronchoalveolar lavage (BAL), and in serum.</p> <p>Results</p> <p>OprF-OprI-specific IgG and IgA antibodies were found in both BAL and IS at comparable rates, but differed in the predominant isotype. IgA antibodies in IS did not correlate to the respective serum levels. Pulmonary antibodies were detectable in all vaccinees even 1 year after the vaccination. The systemic booster group had higher IgG levels in serum. However, the nasal booster group had the better long-term response with bronchial antibodies of both isotypes.</p> <p>Conclusion</p> <p>The nasal OprF-OprI-vaccine induces a lasting antibody response at both, systemic and airway mucosal site. IS is a feasible method to non-invasively assess bronchial antibodies. A further optimization of the vaccination schedule is warranted.</p
Magnetization structure of a Bloch point singularity
Switching of magnetic vortex cores involves a topological transition
characterized by the presence of a magnetization singularity, a point where the
magnetization vanishes (Bloch point). We analytically derive the shape of the
Bloch point that is an extremum of the free energy with exchange, dipole and
the Landau terms for the determination of the local value of the magnetization
modulus.Comment: 4 pages, 2 figure
A Local Superlens
Superlenses enable near-field imaging
beyond the optical diffraction
limit. However, their widespread implementation in optical imaging
technology so far has been limited by large-scale fabrication, fixed
lens position, and specific object materials. Here we demonstrate
that a dielectric lamella of subwavelength size in all three spatial
dimensions behaves as a compact superlens that operates at infrared
wavelengths and can be positioned to image any local microscopic area
of interest on the sample. In particular, the lamella superlens may
be placed in contact with any type of object and therefore enables
examination of hard-to-scan samples, for example, with high topography
or in liquids, without altering the specimen design. This lamella-based
local superlens design is directly applicable to subwavelength light-based
technology, such as integrated optics
Meeting Report: Hackathon-Workshop on Darwin Core and MIxS Standards Alignment
The Global Biodiversity Information Facility and the Genomic Standards Consortium convened a joint workshop at the University of Oxford, 27–29 February 2012, with a small group of experts from Europe, USA, China and Japan, to continue the alignment of the Darwin Core with the MIxS and related genomics standards. Several reference mappings were produced as well as test expressions of MIxS in RDF. The use and management of controlled vocabulary terms was considered in relation to both GBIF and the GSC, and tools for working with terms were reviewed. Extensions for publishing genomic biodiversity data to the GBIF network via a Darwin Core Archive were prototyped and work begun on preparing translations of the Darwin Core to Japanese and Chinese. Five genomic repositories were identified for engagement to begin the process of testing the publishing of genomic data to the GBIF network commencing with the SILVA rRNA database
Photon Beam Asymmetry Σ for η and η′ Photoproduction From the Proton
Measurements of the linearly-polarized photon beam asymmetry Σ for photoproduction from the proton of η and η ′ mesons are reported. A linearly-polarized tagged photon beam produced by coherent bremsstrahlung was incident on a cryogenic hydrogen target within the CEBAF Large Acceptance Spectrometer. Results are presented for the γ p → η p reaction for incident photon energies from 1.070 to 1.876 GeV, and from 1.516 to 1.836 GeV for the γ p → η ′ p reaction. For γ p → η p , the data reported here considerably extend the range of measurements to higher energies, and are consistent with the few previously published measurements for this observable near threshold. For γ p → η ′ p , the results obtained are consistent with the few previously published measurements for this observable near threshold, but also greatly expand the incident photon energy coverage for that reaction. Initial analysis of the data reported here with the Bonn–Gatchina model strengthens the evidence for four nucleon resonances – the N (1895) 1/2− , N (1900) 3/2+ , N(2100) 1/2+ and N (2120) 3/2− resonances – which presently lack the four-star status in the current Particle Data Group compilation, providing examples of how these new measurements help refine models of the photoproduction process
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