44,774 research outputs found
Semileptonic Decay Scalar Form Factor and from Lattice QCD
We present a new study of D semileptonic decays on the lattice which employs
the Highly Improved Staggered Quark (HISQ) action for both the charm and the
light valence quarks. We work with MILC unquenched lattices and
determine the scalar form factor for
semileptonic decays. The form factor is obtained from a scalar current matrix
element that does not require any operator matching. We develop a new approach
to carrying out chiral/continuum extrapolations of . The method uses
the kinematic "" variable instead of or the kaon energy and is
applicable over the entire physical range. We find in the chiral plus
continuum limit and hereby improve the theory error on this quantity by a
factor of 4 compared to previous lattice determinations. Combining the
new theory result with recent experimental measurements of the product from BaBar and CLEO-c leads to the most
precise direct determination of the CKM matrix element to date,
, where the first error comes from experiment and the
second is the lattice QCD theory error. We calculate the ratio and find GeV and show
that this agrees with experiment.Comment: 23 pages, 31 figures, 11 tables. Added a paragraph in sction VII, and
updated with PDG 2010 instead of PDG 200
Enhancement of plasticity in Ti-based metallic glass matrix composites by controlling characteristic and volume fraction of primary phase
In this study, Ti-based metallic glass matrix composites with high plasticity have been developed by controlling characteristic and volume fraction of primary phase embedded in the glass matrix. By careful alloy design procedure, the compositions of ß/glass phases, which are in metastable equilibrium have been properly selected, therefore the mechanical properties can be tailored by selecting the alloy compositions between the composition of ß and glass phases. The relation between the compressive yield strength and volume fraction of ß phase is well described using the rule of mixtures
Fast Fits for Lattice QCD Correlators
We illustrate a technique for fitting lattice QCD correlators to sums of
exponentials that is significantly faster than traditional fitting methods ---
10--40 times faster for the realistic examples we present. Our examples are
drawn from a recent analysis of the Upsilon spectrum, and another recent
analysis of the D -> pi semileptonic form factor. For single correlators, we
show how to simplify traditional effective-mass analyses.Comment: 5 pages, 4 figure
Update: Precision D_s decay constant from full lattice QCD using very fine lattices
We update our previous determination of both the decay constant and the mass
of the meson using the Highly Improved Staggered Quark formalism. We
include additional results at two finer values of the lattice spacing along
with improved determinations of the lattice spacing and improved tuning of the
charm and strange quark masses. We obtain = 1.9691(32) GeV, in good
agreement with experiment, and = 0.2480(25) GeV. Our result for
is 1.6 lower than the most recent experimental average
determined from the leptonic decay rate and using from CKM
unitarity. Combining our with the experimental rate we obtain a
direct determination of , or alternatively using a probability distribution for statistical errors for this
quantity which vanishes above 1. We also include an accurate prediction of the
decay constant of the , = 0.3947(24) GeV, as a calibration
point for other lattice calculations.Comment: 24 pages, 20 figures. Updated to include new experimental results
from BaBar, new experimental averages from HFAG and consequent discussion of
theory/experiment comparison. Other minor typographical changes. Version
accepted by Phys. Rev.
Option Pricing on Renewable Commodity Markets
Options markets on agricultural commodities with maturities that exceed 13 months seldom trade. Our hypothesis is that this market failure is due to the absence of an accurate option pricing model for commodities where mean reversion can be expected. Standard option pricing models assume proportionality between price variance and time to maturity. This proportionality is not a valid assumption for commodities where supply response works to bring prices back to production costs. The model suggests that traditional option pricing models will overprice long-term options on these markets.commodity futures and option, price mean reverting, seasonality, Agricultural Finance, Financial Economics,
Structure of the neutron-rich N=7 isotones 10Li and 9He
The near threshold structure of the unbound N=7 isotones 10Li and 9He has
been investigated using proton removal and breakup from intermediate energy (35
MeV/nucleon) secondary beams of 11Be and 14,15B. The coincident detection of
the beam velocity 9Li and 8He fragments and neutrons permitted the relative
energy of the in-flight decay of 10Li and 9He to be reconstructed. Both systems
were found to exhibited virtual s-wave strength near threshold together with a
higher-lying resonance.Comment: 4 pages, 2 figures, Contribution to INPC2010 - "International Nuclear
Physics Conference", Vancouver, Canada, 4-9 July 2010, Proceedings to be
published in Journal of Physics: Conference Serie
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