Possible resonance free lattices for the VLHC

A systematic search for resonance-free lattices has been performed. Numerous solutions exist for sets of about fifty cells. A VLHC-like machine could be made of blocks of 61 cells which are free from resonances up to tenth order. A tracking test shows a 20% improvement of the dynamic aperture with respect to standard cells, for several multi-pole components. It opens the possibility of relaxing the constraints on systematic multipole components for the cells. The tolerances on field quality will then be by chromatic and an-harmonic effects of the mul-tipole components

The Paraldor Project

Paraldor is an experiment in bringing the power of categorical languages to lattice QCD computations. Our target language is Aldor, which allows the capture of the mathematical structure of physics directly in the structure of the code using the concepts of categories, domains and their inter-relationships in a way which is not otherwise possible with current popular languages such as Fortran, C, C++ or Java. By writing high level physics code portably in Aldor, and implementing switchable machine dependent high performance back-ends in C or assembler, we gain all the power of categorical languages such as modularity, portability, readability and efficiency.Comment: 4 pages, 2 figures, Lattice 2002 conference proceeding

A lattice determination of moments of unpolarised nucleon structure functions using improved Wilson fermions

Within the framework of quenched lattice QCD and using O(a) improved Wilson fermions and non-perturbative renormalisation, a high statistics computation of low moments of the unpolarised nucleon structure functions is given. Particular attention is paid to the chiral and continuum extrapolations.Comment: LaTeX, 66 pages, 22 figure

Topological Structure of the QCD Vacuum Revealed by Overlap Fermions

Overlap fermions preserve a remnant of chiral symmetry on the lattice. They are a powerful tool to investigate the topological structure of the vacuum of Yang-Mills theory and full QCD. Recent results concerning the localization of topological charge and the localization and local chirality of the overlap eigenmodes are reported. The charge distribution is radically different, if a spectral cut-off for the Dirac eigenmodes is applied. The density q(x) is changing from the scale-a charge density (with full lattice resolution) to the ultraviolet filtered charge density. The scale-a density, computed on the Linux cluster of LRZ, has a singular, sign-coherent global structure of co-dimension 1 first described by the Kentucky group. We stress, however, the cluster properties of the UV filtered topological density resembling the instanton picture. The spectral cut-off can be mapped to a bosonic smearing procedure. The UV filtered field strength reveals a high degree of (anti)selfduality at "hot spots" of the action. The fermionic eigenmodes show a high degree of local chirality. The lowest modes are seen to be localized in low-dimensional space-time regions.Comment: 13 pages, 11 figures, accepted to appear in the Proceedings of "HLRB, KONWIHR and Linux-Cluster: Review, Results and Future Projects Workshop", Leibniz Rechenzentrum Munich, December 200

Structure functions and form factors close to the chiral limit from lattice QCD

Results for nucleon matrix elements (arising from moments of structure functions) and form factors from a mixture of runs using Wilson, clover and overlap fermions (both quenched and unquenched) are presented and compared in an effort to explore the size of the chiral `regime', lattice spacing errors and quenching artefacts. While no run covers this whole range of effects the partial results indicate a picture of small lattice spacing errors, small quenching effects and only reaching the chiral regime at rather light quark masses.Comment: 7 pages, 7 figures; contribution to the 2003 Workshop on Lattice Hadron Physics, Cairns, Australia; error in Fig. 4 corrected; minor text change

On the Isomorphic Description of Chiral Symmetry Breaking by Non-Unitary Lie Groups

It is well-known that chiral symmetry breaking ($\chi$SB) in QCD with $N_{f}=2$ light quark flavours can be described by orthogonal groups as $O(4) \to O(3)$, due to local isomorphisms. Here we discuss the question how specific this property is. We consider generalised forms of $\chi$SB involving an arbitrary number of light flavours of continuum or lattice fermions, in various representations. We search systematically for isomorphic descriptions by non-unitary, compact Lie groups. It turns out that there are a few alternative options in terms of orthogonal groups, while we did not find any description entirely based on symplectic or exceptional Lie groups. If we adapt such an alternative as the symmetry breaking pattern for a generalised Higgs mechanism, we may consider a Higgs particle composed of bound fermions and trace back the mass generation to $\chi$SB. In fact, some of the patterns that we encounter appear in technicolour models. In particular if one observes a Higgs mechanism that can be expressed in terms of orthogonal groups, we specify in which cases it could also represent some kind of $\chi$SB of techniquarks.Comment: 18 pages, to appear in Int. J. Mod. Phys.

Hadron spectrum, quark masses and decay constants from light overlap fermions on large lattices

We present results from a simulation of quenched overlap fermions with L\"uscher-Weisz gauge field action on lattices up to $24^3 48$ and for pion masses down to $\approx 250$ MeV. Among the quantities we study are the pion, rho and nucleon masses, the light and strange quark masses, and the pion decay constant. The renormalization of the scalar and axial vector currents is done nonperturbatively in the $RI-MOM$ scheme. The simulations are performed at two different lattice spacings, $a \approx 0.1$ fm and $\approx 0.15$ fm, and on two different physical volumes, to test the scaling properties of our action and to study finite volume effects. We compare our results with the predictions of chiral perturbation theory and compute several of its low-energy constants. The pion mass is computed in sectors of fixed topology as well

Understanding the experience of initiating community-based physical activity and social support by people with serious mental illness: a systematic review using a meta-ethnographic approach

Background People with long-term serious mental illness live with severe and debilitating symptoms that can negatively influence their health and quality of life, leading to outcomes such as premature mortality, morbidity and obesity. An interplay of social, behavioural, biological and psychological factors is likely to contribute to their poor physical health. Participating in regular physical activity could bring symptomatic improvements, weight loss benefits, enhanced wellbeing and when undertaken in a community-based group setting can yield additional, important social support benefits. Yet poor uptake of physical activity by people with serious mental illness is a problem. This review will systematically search, appraise and synthesise the existing evidence that has explored the experience of community-based physical activity initiation and key features of social support within these contexts by adults with schizophrenia, bipolar affective disorder, major depressive disorder or psychosis using the meta-ethnography approach. This new understanding may be key in designing more acceptable and effective community-based group PA programmes that meet patients’ need and expectations. Methods This will be a systematic review of qualitative studies using the meta-ethnography approach. The following databases will be searched: ASSIA, CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, Health Technology Assessment Database, MEDLINE, PsycINFO, Sociological Abstracts, SPORTDiscus and Web of Science. Grey literature will also be sought. Eligible studies will use qualitative methodology; involve adults (≥18 years) with schizophrenia, bipolar affective disorder, major depressive disorder or psychosis; will report community-based group physical activity; and capture the experience of physical activity initiation and key features of social support from the perspective of the participant. Study selection and assessment of quality will be performed by two reviewers. Data will be extracted by one reviewer, tabled, and checked for accuracy by the second reviewer. The meta-ethnography approach by Noblit and Hare [1] will be used to synthesise the data. Discussion This systematic review is expected to provide new insights into the experience of community-based group physical activity initiation for adults who have a serious mental illness to inform person-centred improvements to the management of serious mental illness through physical activity. Registration The protocol has been registered on the International Prospective Register of Systematic Reviews (PROSPERO) on 22/03/2017; http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42017059948 (registration number CRD42017059948). Keywords Serious mental illness - Physical activity - Community - Social support - Exercise - Sport - Adults - Patient experience - Qualitative research - Meta-ethnography - Systematic revie

Real-time time-domain fluorescence lifetime imaging including single-shot acquisition with a segmented optical image intensifier

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