2,855 research outputs found
Nucleon electromagnetic form factors from lattice QCD using a nearly physical pion mass
We present lattice QCD calculations of nucleon electromagnetic form factors
using pion masses = 149, 202, and 254 MeV and an action with
clover-improved Wilson quarks coupled to smeared gauge fields, as used by the
Budapest-Marseille-Wuppertal collaboration. Particular attention is given to
removal of the effects of excited state contamination by calculation at three
source-sink separations and use of the summation and generalized
pencil-of-function methods. The combination of calculation at the nearly
physical mass = 149 MeV in a large spatial volume ( = 4.2)
and removal of excited state effects yields agreement with experiment for the
electric and magnetic form factors and up to = 0.5
GeV.Comment: v2: published version; 30 pages, 25 figures, 6 table
On Hecke theory for Hermitian modular forms
In this paper we outline the Hecke theory for Hermitian modular forms in the
sense of Hel Braun for arbitrary class number of the attached
imaginary-quadratic number field. The Hecke algebra turns out to be
commutative. Its inert part has a structure analogous to the case of the Siegel
modular group and coincides with the tensor product of its -components for
inert primes . This leads to a characterization of the associated
Siegel-Eisenstein series. The proof also involves Hecke theory for particular
congruence subgroups
Initial nucleon structure results with chiral quarks at the physical point
We report initial nucleon structure results computed on lattices with 2+1
dynamical M\"obius domain wall fermions at the physical point generated by the
RBC and UKQCD collaborations. At this stage, we evaluate only connected quark
contributions. In particular, we discuss the nucleon vector and axial-vector
form factors, nucleon axial charge and the isovector quark momentum fraction.
From currently available statistics, we estimate the stochastic accuracy of the
determination of and to be around 10%, and we expect to
reduce that to 5% within the next year. To reduce the computational cost of our
calculations, we extensively use acceleration techniques such as low-eigenmode
deflation and all-mode-averaging (AMA). We present a method for choosing
optimal AMA parameters.Comment: 7 pages, 11 figures; talk presented at the 32nd International
Symposium on Lattice Field Theory, 23-28 June, 2014, Columbia University, New
York, US
Thermodynamic properties of QCD in external magnetic fields
We consider the effect of strong external electromagnetic fields on
thermodynamic observables in QCD, through lattice simulations with 1+1+1
flavors of staggered quarks at physical quark masses. Continuum extrapolated
results are presented for the light quark condensates and for their tensor
polarizations, as functions of the temperature and the magnetic field. We find
the light condensates to undergo inverse magnetic catalysis in the transition
region, in a manner that the transition temperature decreases with growing
magnetic field. We also compare the results to other approaches and lattice
simulations. Furthermore, we relate the tensor polarization to the spin part of
the magnetic susceptibility of the QCD vacuum, and show that this contribution
is diamagnetic.Comment: 13 pages, 9 figures, talks presented by FB and GE at Xth Quark
Confinement and the Hadron Spectrum, 8-12 October 2012, TUM Campus Garching,
Munich, German
Postgraduate Symposium Positive influence of nutritional alkalinity on bone health: Conference on ‘Over- and undernutrition: challenges and approaches'
There is growing evidence that consumption of a Western diet is a risk factor for osteoporosis through excess acid supply, while fruits and vegetables balance the excess acidity, mostly by providing K-rich bicarbonate-rich foods. Western diets consumed by adults generate approximately 50-100 mEq acid/d; therefore, healthy adults consuming such a diet are at risk of chronic low-grade metabolic acidosis, which worsens with age as a result of declining kidney function. Bone buffers the excess acid by delivering cations and it is considered that with time an overstimulation of this process will lead to the dissolution of the bone mineral content and hence to reduced bone mass. Intakes of K, Mg and fruit and vegetables have been associated with a higher alkaline status and a subsequent beneficial effect on bone health. In healthy male volunteers an acid-forming diet increases urinary Ca excretion by 74% and urinary C-terminal telopeptide of type I collagen (C-telopeptide) excretion by 19% when compared with an alkali (base-forming) diet. Cross-sectional studies have shown that there is a correlation between the nutritional acid load and bone health measured by bone ultrasound or dual-energy X-ray absorptiometry. Few studies have been undertaken in very elderly women (>75 years), whose osteoporosis risk is very pertinent. The EVAluation of Nutrients Intakes and Bone Ultra Sound Study has developed and validated (n 51) an FFQ for use in a very elderly Swiss population (mean age 80·4 (sd 2·99) years), which has shown intakes of key nutrients (energy, fat, carbohydrate, Ca, Mg, vitamin C, D and E) to be low in 401 subjects. A subsequent study to assess net endogenous acid production (NEAP) and bone ultrasound results in 256 women aged ≥75 years has shown that lower NEAP (P=0·023) and higher K intake (P=0·033) are correlated with higher bone ultrasound results. High acid load may be an important additional risk factor that may be particularly relevant in very elderly patients with an already-high fracture risk. The latter study adds to knowledge by confirming a positive link between dietary alkalinity and bone health indices in the very elderly. In a further study to complement these findings it has also been shown in a group of thirty young women that in Ca sufficiency an acid Ca-rich water has no effect on bone resorption, while an alkaline bicarbonate-rich water leads to a decrease in both serum parathyroid hormone and serum C-telopeptide. Further investigations need to be undertaken to study whether these positive effects on bone loss are maintained over long-term treatment. Mineral-water consumption could be an easy and inexpensive way of helping to prevent osteoporosis and could be of major interest for long-term prevention of bone los
Wage Distribution Impacts of Higher Education Faculty Unionization
The literature on the effects of unions on the distribution of wages at the macroeconomic and inter-industry levels has given little attention to the effects at the firm level. At the same time, research on collective bargaining impacts in higher education has focused on the overall wage level rather than on the distribution of salaries. Using panel data on individual faculty members, we find faculty unionization to be associated with a significant flattening of the wage distribution across academic disciplines. This has implications for why faculty might choose to unionize, even in the absence of an overall wage premium
From Ji to Jaffe-Manohar orbital angular momentum in Lattice QCD using a direct derivative method
A Lattice QCD approach to quark orbital angular momentum in the proton based
on generalized transverse momentum-dependent parton distributions (GTMDs) is
enhanced methodologically by incorporating a direct derivative technique. This
improvement removes a significant numerical bias that had been seen to afflict
results of a previous study. In particular, the value obtained for Ji quark
orbital angular momentum is reconciled with the one obtained independently via
Ji's sum rule, validating the GMTD approach. Since GTMDs simultaneously contain
information about the quark impact parameter and transverse momentum, they
permit a direct evaluation of the cross product of the latter. They are defined
through proton matrix elements of a quark bilocal operator containing a Wilson
line; the choice in Wilson line path allows one to continuously interpolate
from Ji to Jaffe-Manohar quark orbital angular momentum. The latter is seen to
be significantly enhanced in magnitude compared to Ji quark orbital angular
momentum, confirming previous results.Comment: 12 pages, 6 figure
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