856 research outputs found
RI/MOM and RI/SMOM renormalization of overlap quark bilinears on domain wall fermion configurations
Renormalization constants (RCs) of overlap quark bilinear operators on
2+1-flavor domain wall fermion configurations are calculated by using the
RI/MOM and RI/SMOM schemes. The scale independent RC for the axial vector
current is computed by using a Ward identity. Then the RCs for the quark field
and the vector, tensor, scalar and pseudoscalar operators are calculated in
both the RI/MOM and RI/SMOM schemes. The RCs are converted to the
scheme and we compare the numerical results from using the
two intermediate schemes. The lattice size is and the inverse
spacing .Comment: Minor changes and updates of Figure 10 and 15 to be more clea
Meson Mass Decomposition
Hadron masses can be decomposed as a sum of components which are defined
through hadronic matrix elements of QCD operators. The components consist of
the quark mass term, the quark energy term, the glue energy term and the trace
anomaly term. We calculate these components of mesons with lattice QCD for the
first time. The calculation is carried out with overlap fermion on flavor
domain-wall fermion gauge configurations. We confirm that of the
light pion mass comes from the quark mass and comes from the quark
energy, whereas, the contributions are found to be the other way around for the
mass. The combined glue components contribute for both
mesons. It is interesting to observe that the quark mass contribution to the
mass of the vector meson is almost linear in quark mass over a large quark mass
region below the charm quark mass. For heavy mesons, the quark mass term
dominates the masses, while the contribution from the glue components is about
MeV for the heavy pseudoscalar and vector mesons. The charmonium
hyperfine splitting is found to be dominated by the quark energy term which is
consistent with the quark potential model.Comment: 7 Pages, 4 figures, contribution to the 32nd International Symposium
on Lattice Field Theory (Lattice 2014), 23-28 June 2014, Columbia University,
New York, NY, US
Global dynamics of a class of HIV-1 infection models with latently infected cells
In this paper, the global dynamics of a class of HIV-1 infection models with different infection rates and latently infected cells are investigated. We first modify the basic virus infection model and propose two models with bilinear infection rate and saturation infection rate, respectively, which take HIV-1 latency into consideration, and then study a model with a general nonlinear infection rate. By using proper Lyapunov functions and LaSalle's invariance principle, it is proved that in the first two models, if the basic reproduction ratio is less than unity, each of the infection-free equilibria is globally asymptotically stable; if the basic reproduction ratio is greater than unity, each of the chronic-infection equilibria is globally asymptotically stable. For the last model with general nonlinear infection rate, we obtain sufficient conditions for the global stability of both the infection-free and chronic-infection equilibria of the model
Non-perturbative renormalization of overlap quark bilinears on 2+1-flavor domain wall fermion configurations
We present renormalization constants of overlap quark bilinear operators on
2+1-flavor domain wall fermion configurations. This setup is being used by the
chiQCD collaboration in calculations of physical quantities such as strangeness
in the nucleon and the strange and charm quark masses. The scale independent
renormalization constant for the axial vector current is computed using the
Ward Identity. The renormalization constants for scalar, pseudoscalar and
vector current are calculated in the RI-MOM scheme. Results in the MS-bar
scheme are also given. The step scaling function of quark masses in the RI-MOM
scheme is computed as well. The analysis uses, in total, six different
ensembles of three sea quarks each on two lattices with sizes 24^3x64 and
32^3x64 at spacings a=(1.73 GeV)^{-1} and (2.28 GeV)^{-1}, respectively.Comment: 26 pages, 17 figures. More discussions on O(4) breaking effects, and
on the perturbative running and a^2p^2 extrapolation of Zs. A subsection for
the calculation of the step scaling function of quark mass is added.
References added. Version to appear in PR
Two Photon Decays of from Lattice QCD
We present an exploratory lattice study for the two-photon decay of
using twisted mass lattice QCD gauge configurations generated by the
European Twisted Mass Collaboration. Two different lattice spacings of
fm and fm are used in the study, both of which are of
physical size of 2. The decay widths are found to be KeV for the
coarser lattice and KeV for the finer lattice respectively where the
errors are purely statistical. A naive extrapolation towards the continuum
limit yields KeV which is smaller than the previous
quenched result and most of the current experimental results. Possible reasons
are discussed.Comment: 13 pages, 7 figures; matches the published versio
Coherency in Neutrino-Nucleus Elastic Scattering
Neutrino-nucleus elastic scattering provides a unique laboratory to study the
quantum mechanical coherency effects in electroweak interactions, towards which
several experimental programs are being actively pursued. We report results of
our quantitative studies on the transitions towards decoherency. A parameter
() is identified to describe the degree of coherency, and its
variations with incoming neutrino energy, detector threshold and target nucleus
are studied. The ranges of which can be probed with realistic neutrino
experiments are derived, indicating complementarity between projects with
different sources and targets. Uncertainties in nuclear physics and in
would constrain sensitivities in probing physics beyond the standard model. The
maximum neutrino energies corresponding to >0.95 are derived.Comment: 5 pages, 4 figures, 3 tables. V2 -- Published Versio
Cost-effectiveness of compression technologies for evidence-informed leg ulcer care: results from the Canadian Bandaging Trial
BACKGROUND: Venous leg ulcers, affecting approximately 1% of the population, are costly to manage due to poor healing and high recurrence rates. We evaluated an evidence-informed leg ulcer care protocol with two frequently used high compression systems: ‘four-layer bandage’ (4LB) and ‘short-stretch bandage’ (SSB). METHODS: We conducted a cost-effectiveness analysis using individual patient data from the Canadian Bandaging Trial, a publicly funded, pragmatic, randomized trial evaluating high compression therapy with 4LB (n = 215) and SSB (n = 209) for community care of venous leg ulcers. We estimated costs (in 2009–2010 Canadian dollars) from the societal perspective and used a time horizon corresponding to each trial participant’s first year. RESULTS: Relative to SSB, 4LB was associated with an average 15 ulcer-free days gained, although the 95% confidence interval [−32, 21 days] crossed zero, indicating no treatment difference; an average health benefit of 0.009 QALYs gained [−0.019, 0.037] and overall, an average cost increase of 235, 46,667 per QALY gained. If decision makers are willing to pay from 100,000 per QALY, the probability of 4LB being more cost effective increased from 51% to 63%. CONCLUSIONS: Our findings differ from the emerging clinical and economic evidence that supports high compression therapy with 4LB, and therefore suggest another perspective on high compression practice, namely when delivered by trained registered nurses using an evidence-informed protocol, both 4LB and SSB systems offer comparable effectiveness and value for money. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT0020226
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