Spin density matrix elements in vector meson leptoproduction

It is reported on an analysis of vector meson leptoproduction at small Bjorken-$x$ and large photon virtuality within an approach that bases on generalized parton distributions (GPDs). This approach leads to results for cross sections and spin density matrix elements for $\rho$ and $\phi$ leptoproduction in fair agreement with experiment.Comment: Report at Spin 2004 Symposium, October 10-16, Trieste, Ital

Transversity in exclusive vector-meson leptoproduction

The role of transversity or helicity-flip generalized parton distributions (GPDs) in leptoproduction of vector mesons is investigated within the framework of the handbag approach. The transversity GPDs in combination with twist-3 meson wave functions, occur in the amplitudes for transitions from a transversely polarized virtual photon to a longitudinal polarized vector meson. The importance of the transversity GPDs can be examined in some of the spin density matrix elements and in transverse target spin asymmetries. Using suitable parametrizations of both helicity-flip and non-flip GPDs, which are essentially taken from our previous papers, we estimate these observables and compare the results with available data.Comment: 30 pages, 19 figure

The pion pole in hard exclusive vector-meson leptoproduction

Exploiting a set of generalized parton distributions (GPDs) derived from analyses of hard exclusive leptoproduction of rho0, phi and pi+ mesons, we investigate the omega spin density matrix elements (SDMEs) recently measured by the HERMES collaboration. It turns out from our study that the pion pole is an important contribution to omega production. It will be treated as a one-particle exchange since its evaluation from the GPD E-tilde considerably underestimates its contribution. As an intermediate step of our analysis we extract the pi-omega transition form factor for photon virtualities less than 4 GeV^2. From our approach we achieve results for the omega SDMEs in good agreement with the HERMES data. The role of the pion pole in exclusive rho0 and phi leptoproduction is discussed too.Comment: 27 pages, 33 figure

The exclusive limit of the pion-induced Drell-Yan process

Based on previous studies of hard exclusive leptoproduction of pions in which the essential role of the pion pole and the transversity generalized parton distributions has been pointed out, we present predictions for the four partial cross sections of the exclusive Drell-Yan process, pi^-p -> l^-l^+n.Comment: 14 pages, 6 figure

Patient-reported outcome measures for chronic obstructive pulmonary disease: the exclusion of people with low literacy skills and learning disabilities

<p>Background: Patient-reported outcome measures (PROMs) are intended to reflect outcomes relevant to patients. They are increasingly used for healthcare quality improvement. To produce valid measures, patients should be involved in the development process but it is unclear whether this usually includes people with low literacy skills or learning disabilities. This potential exclusion raises concerns about whether these groups will be able to use these measures and participate in quality improvement practices.</p> <p>Methods: Taking PROMs for chronic obstructive pulmonary disease (COPD) as an exemplar condition, our review determined the inclusion of people with low literacy skills and learning disabilities in research developing, validating, and using 12 PROMs for COPD patients. The studies included in our review were based on those identified in two existing systematic reviews and our update of this search. Results People with low literacy skills and/or learning disabilities were excluded from the development of PROMs in two ways: explicitly through the participant eligibility criteria and, more commonly, implicitly through recruitment or administration methods that would require high-level reading and cognitive abilities. None of the studies mentioned efforts to include people with low literacy skills or learning disabilities.</p> <p>Conclusion: Our findings suggest that people with low literacy skills or learning disabilities are left out of the development of PROMs. Given that implicit exclusion was most common, researchers and those who administer PROMs may not even be aware of this problem. Without effort to improve inclusion, unequal quality improvement practices may become embedded in the health system.</p&gt

Initial experiments concerning quantum information processing in rare-earth-ion doped crystals

In this paper initial experiments towards constructing simple quantum gates in a solid state material are presented. Instead of using specially tailored materials, the aim is to select a subset of randomly distributed ions in the material, which have the interaction necessary to control each other and therefore can be used to do quantum logic operations. The experimental results demonstrate that part of an inhomogeneously broadened absorption line can be selected as a qubit and that a subset of ions in the material can control the resonance frequency of other ions. This opens the way for the construction of quantum gates in rare-earth-ion doped crystals.Comment: 24 pages, including 12 figure