6,844 research outputs found
Piezoelectric-based apparatus for strain tuning
We report the design and construction of piezoelectric-based apparatus for
applying continuously tuneable compressive and tensile strains to test samples.
It can be used across a wide temperature range, including cryogenic
temperatures. The achievable strain is large, so far up to 0.23% at cryogenic
temperatures. The apparatus is compact and compatible with a wide variety of
experimental probes. In addition, we present a method for mounting
high-aspect-ratio samples in order to achieve high strain homogeneity.Comment: 8 pages, 8 figure
More about orbitally excited hadrons from lattice QCD
This is a second paper describing the calculation of spectroscopy for
orbitally excited states from lattice simulations of Quantum Chromodynamics.
New features include higher statistics for P-wave systems and first results for
the spectroscopy of D-wave mesons and baryons, for relatively heavy quark
masses. We parameterize the Coulomb gauge wave functions for P-wave and D-wave
systems and compare them to those of their corresponding S-wave states.Comment: 21 pages plus 14 figs, 3 include
Mechanisms and Clinical Consequences of Vascular Calcification
Vascular calcification has severe clinical consequences and is considered an accurate predictor of future adverse cardiovascular events, including myocardial infarction and stroke. Previously vascular calcification was thought to be a passive process which involved the deposition of calcium and phosphate in arteries and cardiac valves. However, recent studies have shown that vascular calcification is a highly regulated, cell-mediated process similar to bone formation. In this article, we outline the current understanding of key mechanisms governing vascular calcification and highlight the clinical consequences. By understanding better the molecular pathways and genetic circuitry responsible for the pathological mineralization process novel drug targets may be identified and exploited to combat and reduce the detrimental effects of vascular calcification on human health
Classical field theory on Lie algebroids: Variational aspects
The variational formalism for classical field theories is extended to the
setting of Lie algebroids. Given a Lagrangian function we study the problem of
finding critical points of the action functional when we restrict the fields to
be morphisms of Lie algebroids. In addition to the standard case, our formalism
includes as particular examples the case of systems with symmetry (covariant
Euler-Poincare and Lagrange Poincare cases), Sigma models or Chern-Simons
theories.Comment: Talk deliverd at the 9th International Conference on Differential
Geometry and its Applications, Prague, September 2004. References adde
Gluonic and leptonic decays of heavy quarkonia and the determination of and
QCD running coupling constant and are
determined from heavy quarkonia and decays. The
decay rates of and for and
are estimated by taking into account both relativistic and QCD
radiative corrections. The decay amplitudes are derived in the Bethe-Salpeter
formalism, and the decay rates are estimated by using the meson wavefunctions
which are obtained with a QCD-inspired inter-quark potential. For the
decay we find the relativistic correction to be very large
and to severely suppress the decay rate. Using the experimental values of ratio
R_g\equiv \frac {\Gamma (V\longrightarrow 3g)}% {\Gamma (V\longrightarrow
e^{+}e^{-})}\approx 10,~32 for respectively, and the
calculated widths , we find and
. These values for the QCD running coupling
constant are substantially enhanced, as compared with the ones obtained without
relativistic corrections, and are consistent with the QCD scale parameter
. We also find that these
results are mainly due to kinematic corrections and not sensitive to the
dynamical models.Comment: 15 pages in Late
Summary: Working Group on QCD and Strong Interactions
In this summary of the considerations of the QCD working group at Snowmass
2001, the roles of quantum chromodynamics in the Standard Model and in the
search for new physics are reviewed, with empahsis on frontier areas in the
field. We discuss the importance of, and prospects for, precision QCD in
perturbative and lattice calculations. We describe new ideas in the analysis of
parton distribution functions and jet structure, and review progress in
small- and in polarization.Comment: Snowmass 2001. Revtex4, 34 pages, 4 figures, revised to include
additional references on jets and lattice QC
B and D Meson Decay Constants in Lattice QCD
We have calculated the decay constants of B and mesons with lattice QCD.
We use an improved action that takes light quark actions as a starting
point, tuned so that it can be directly applied at the physical masses of the
and quarks. Our results are f_B = 164 \err{+14}{-11} \pm 8 MeV,
f_{B_s} = 185 \err{+13}{-8} \pm 9 MeV, f_D = 194 \err{+14}{-10} \pm 10 MeV,
and f_{D_s} = 213 \err{+14}{-11} \pm 11 MeV in the quenched approximation.
The first error in each case is statistical, and the second is from
perturbation theory. We show that discretization errors are under control in
our approach, and smaller than our statistical errors. The effects of the
quenched approximation may raise our quenched result by up to 10%.Comment: 21 pages, 6 figure
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