964 research outputs found
B-meson decay constants: a more complete picture from full lattice QCD
We extend the picture of -meson decay constants obtained in lattice QCD
beyond those of the , and to give the first full lattice QCD
results for the , and . We use improved NonRelativistic QCD
for the valence quark and the Highly Improved Staggered Quark (HISQ) action
for the lighter quarks on gluon field configurations that include the effect of
, and quarks in the sea with quark masses going down to
physical values. For the ratio of vector to pseudoscalar decay constants, we
find = 0.941(26), = 0.953(23) (both
less than 1.0) and = 0.988(27). Taking correlated
uncertainties into account we see clear indications that the ratio increases as
the mass of the lighter quark increases. We compare our results to those using
the HISQ formalism for all quarks and find good agreement both on decay
constant values when the heaviest quark is a and on the dependence on the
mass of the heaviest quark in the region of the . Finally, we give an
overview plot of decay constants for gold-plated mesons, the most complete
picture of these hadronic parameters to date.Comment: 20 pages, 9 figures. Minor updates to the discussion in several
places and some additional reference
Report on R. V. Akademik Vernadsky cruise 39, stage IV, June 17 - July 17, 1989
Participation by U. S. personnel on Cruise 39, Leg IV (June 17 - July 17, 1989) of the Marine Hydrophysical Institute's
research vessel Akademik Vernadsky provided valuable information, documented in the present report for planning future cooperative
projects with Soviet oceanographers. Detailed descriptions are given of the ship, its scientific laboratories, computers and onboard
instrumentation. Planning and operating procedures are described and examples are given of daily work plans, seminars,
menus and social activities. Personal accounts by the U. S. participants are also included. Many of the shipboard activities were
recorded on VHS video cassettes.
The oceanographic data collected in the Gulf Stream survey region during Leg IV are documented in the report. Copies of
data sets were provided to the U. S. participants in exchange for U. S. data from the region during the survey period.Funding was provided by Vetelsen,
the Education Office of Woods Hole Oceanographic Institution, and
a Dr. Willam B. Richardson Summer Fellowship provided by
Alden Products Company
Conceptualizing the Science-Practice Interface: Lessons from a Collaborative Network on the Front-Line of Climate Change
The gap between science and practice is widely recognized as a major concern in the production and application of decision-relevant science. This research analyzed the roles and network connections of scientists, service providers, and decision makers engaged in climate science and adaptation practice in Alaska, where rapid climate change is already apparent. Our findings identify key actors as well as significant differences in the level of bonding ties between network members who perceive similarity in their social identities, bridging ties between network members across different social groups, and control of information across roles—all of which inform recommendations for adaptive capacity and the co-production of usable knowledge. We also find that some individuals engage in multiple roles in the network suggesting that conceptualizing science policy interactions with the traditional categories of science producers and consumers oversimplifies how experts engage with climate science, services, and decision making. Our research reinforces the notion that the development and application of knowledge is a networked phenomenon and highlights the importance of centralized individuals capable of playing multiple roles in their networks for effective translation of knowledge into action
Research Proposal for an Experiment to Search for the Decay {\mu} -> eee
We propose an experiment (Mu3e) to search for the lepton flavour violating
decay mu+ -> e+e-e+. We aim for an ultimate sensitivity of one in 10^16
mu-decays, four orders of magnitude better than previous searches. This
sensitivity is made possible by exploiting modern silicon pixel detectors
providing high spatial resolution and hodoscopes using scintillating fibres and
tiles providing precise timing information at high particle rates.Comment: Research proposal submitted to the Paul Scherrer Institute Research
Committee for Particle Physics at the Ring Cyclotron, 104 page
Advanced modelling of the Planck-LFI radiometers
The Low Frequency Instrument (LFI) is a radiometer array covering the 30-70
GHz spectral range on-board the ESA Planck satellite, launched on May 14th,
2009 to observe the cosmic microwave background (CMB) with unprecedented
precision. In this paper we describe the development and validation of a
software model of the LFI pseudo-correlation receivers which enables to
reproduce and predict all the main system parameters of interest as measured at
each of the 44 LFI detectors. These include system total gain, noise
temperature, band-pass response, non-linear response. The LFI Advanced RF Model
(LARFM) has been constructed by using commercial software tools and data of
each radiometer component as measured at single unit level. The LARFM has been
successfully used to reproduce the LFI behavior observed during the LFI
ground-test campaign. The model is an essential element in the database of LFI
data processing center and will be available for any detailed study of
radiometer behaviour during the survey.Comment: 21 pages, 15 figures, this paper is part of the Prelaunch status LFI
papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jins
Cross-talk compensation of hyperfine control in donor qubit architectures
We theoretically investigate cross-talk in hyperfine gate control of
donor-qubit quantum computer architectures, in particular the Kane proposal. By
numerically solving the Poisson and Schr\"{o}dinger equations for the gated
donor system, we calculate the change in hyperfine coupling and thus the error
in spin-rotation for the donor nuclear-electron spin system, as the gate-donor
distance is varied. We thus determine the effect of cross-talk - the
inadvertent effect on non-target neighbouring qubits - which occurs due to
closeness of the control gates (20-30nm). The use of compensation protocols is
investigated, whereby the extent of crosstalk is limited by the application of
compensation bias to a series of gates. In light of these factors the
architectural implications are then considered.Comment: 15 pages, 22 figures, submitted to Nanotechnolog
‘I’ve got lots of gaps, but I want to hang on to the ones that I have’: The ageing body, oral health and stories of the mouth
The mouth may be presented and understood in different ways, be subject to judgement by others and, as we age, may intrude on everyday life due to problems that affect oral health. However, research that considers older people's experiences concerning their mouths and teeth is limited. This paper reports on qualitative research with 43 people in England and Scotland, aged 65–91, exploring the significance of the mouth over the lifecourse. It uses the concept of ‘mouth talk’ to explore narratives of maintaining, losing and replacing teeth. Participants engaged in ‘mouth talk’ to downplay the impact of the mouth, demonstrate socially appropriate ageing, and distance themselves from ‘real’ old age by retaining a moral identity and sense of self. They also found means to challenge dominant discourses of ageing in how they spoke about missing teeth. Referring to Leder's notion of ‘dys-appearance’ and Gilleard and Higgs’ work on the social imaginary of the fourth age, the study illustrates the ways in which ‘mouth talk’ can contribute to sustaining a sense of self in later life, presenting the ageing mouth, with and without teeth, as an absent presence. It also argues for the importance of listening to stories of the mouth in order to expand understanding of people's approaches to oral health in older age
LFI 30 and 44 GHz receivers Back-End Modules
The 30 and 44 GHz Back End Modules (BEM) for the Planck Low Frequency
Instrument are broadband receivers (20% relative bandwidth) working at room
temperature. The signals coming from the Front End Module are amplified, band
pass filtered and finally converted to DC by a detector diode. Each receiver
has two identical branches following the differential scheme of the Planck
radiometers. The BEM design is based on MMIC Low Noise Amplifiers using GaAs
P-HEMT devices, microstrip filters and Schottky diode detectors. Their
manufacturing development has included elegant breadboard prototypes and
finally qualification and flight model units. Electrical, mechanical and
environmental tests were carried out for the characterization and verification
of the manufactured BEMs. A description of the 30 and 44 GHz Back End Modules
of Planck-LFI radiometers is given, with details of the tests done to determine
their electrical and environmental performances. The electrical performances of
the 30 and 44 GHz Back End Modules: frequency response, effective bandwidth,
equivalent noise temperature, 1/f noise and linearity are presented
Thermal susceptibility of the Planck-LFI receivers
This paper is part of the Prelaunch status LFI papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jinst .
This paper describes the impact of the Planck Low Frequency Instrument front
end physical temperature fluctuations on the output signal. The origin of
thermal instabilities in the instrument are discussed, and an analytical model
of their propagation and impact on the receivers signal is described. The
experimental test setup dedicated to evaluate these effects during the
instrument ground calibration is reported together with data analysis methods.
Finally, main results obtained are discussed and compared to the requirements.Comment: This is an author-created, un-copyedited version of an article
accepted for publication in Journal of Instrumentation. IOP Publishing Ltd is
not responsible for any errors or omissions in this version of the manuscript
or any version derived from it. The definitive publisher authenticated
version is available online at 10.1088/1748-0221/4/12/T1201
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