178,178 research outputs found
Uniqueness for diffusions degenerating at the boundary of a smooth bounded set
For continuous \gamma, g:[0,1]\to(0,\infty), consider the degenerate
stochastic differential equation dX_t=[1-|X_t|^2]^{1/2}\gamma(|X_t|)
dB_t-g(|X_t|)X_t dt in the closed unit ball of R^n. We introduce a new idea to
show pathwise uniqueness holds when \gamma and g are Lipschitz and
\frac{g(1)}{\gamma^2(1)}>\sqrt2-1. When specialized to a case studied by Swart
[Stochastic Process. Appl. 98 (2002) 131-149] with \gamma=\sqrt2 and g\equiv c,
this gives an improvement of his result. Our method applies to more general
contexts as well. Let D be a bounded open set with C^3 boundary and suppose
h:\barD\to R Lipschitz on \barD, as well as C^2 on a neighborhood of \partial D
with Lipschitz second partials there. Also assume h>0 on D, h=0 on \partial D
and |\nabla h|>0 on \partial D. An example of such a function is
h(x)=d(x,\partial D). We give conditions which ensure pathwise uniqueness holds
for dX_t=h(X_t)^{1/2}\sigma(X_t) dB_t+b(X_t) dt in \barD.Comment: Published at http://dx.doi.org/10.1214/009117904000000810 in the
Annals of Probability (http://www.imstat.org/aop/) by the Institute of
Mathematical Statistics (http://www.imstat.org
J/psi couplings to charmed resonances and to pi
We present an evaluation of the strong couplings JD^(*)D^(*) and
JD^(*)D^(*)pi by an effective field theory of quarks and mesons. These
couplings are necessary to calculate pi+J/psi --> D^(*)+barD^(*) cross
sections, an important background to the J/psi suppression signal in the
quark-gluon plasma. We write down the general effective lagrangian and compute
the relevant couplings in the soft pion limit and beyond.Comment: 11 pages, 4 figures, 2 reference added and minor comments, style
changed to RevTe
Final state phases in B -> D\pi, \bar{D}\pi decays and CP-asymmetry
Final state phases \delta_f and \delta_f' in B-> D pi, barD pi decays are
shown to be equal i.e. \delta =\delta_f-\delta_f' = 0. Thus CP-violating
asymmetry A(t) is independent of final state phases. The estimate for the
phases \delta_f and \delta_f' is also given.Comment: 6 pages, no figur
Volume 12, Number 1 - November 1931
Volume 12, Number 1 – November 1931. 26 pages including covers and advertisements. Shea, Frank G. An Open Letter to a Freshman Curran, Paul Hearn - Japan\u27s Interpreter Norback, Howard G. Frank Stanton - Dixie\u27s Bard McDonough, John J. Verse McDonough, John J. O Quam Pulchra est Casta Generatio McDonough, John J. Memory Gaol Nestor, Thomas A. Pride Cometh Editorials Leverone, Charles E. She Dined Alone Haylon, William D. Campus Chronicle O\u27Neill, Matthew F. The Alumni Corner Tebbetts, George Athletic
Measurement of Absolute Hadronic Branching Fractions of D Mesons and e^+e^- --> D barD Cross Sections at E_cm = 3773 MeV
Using 55.8 pb^-1 of e^+e^- collisions recorded at the psi(3770) resonance
with the CLEO-c detector at CESR, we determine absolute hadronic branching
fractions of charged and neutral D mesons using a double tag technique. Among
measurements for three D^0 and six D^+ modes, we obtain reference branching
fractions B(D^0 -> K^- pi^+)=(3.91 +- 0.08 +- 0.09)% and B(D^+ -> K^- pi^+
pi^+)=(9.5 +- 0.2 +- 0.3)%, where the uncertainties are statistical and
systematic, respectively. Final state radiation is included in these branching
fractions by allowing for additional, unobserved, photons in the final state.
Using a determination of the integrated luminosity, we also extract the cross
sections sigma(e^+e^- -> D^0 \bar D^0)=(3.60 +- 0.07 +0.07-0.05) nb and
sigma(e^+e^- -> D^+D^-)=(2.79 +- 0.07 +0.10-0.04) nb.Comment: 9 pages postscript,also available through
http://www.lns.cornell.edu/public/CLNS/2005/, submitted to PR
Spurious Shear in Weak Lensing with LSST
The complete 10-year survey from the Large Synoptic Survey Telescope (LSST)
will image 20,000 square degrees of sky in six filter bands every few
nights, bringing the final survey depth to , with over 4 billion
well measured galaxies. To take full advantage of this unprecedented
statistical power, the systematic errors associated with weak lensing
measurements need to be controlled to a level similar to the statistical
errors.
This work is the first attempt to quantitatively estimate the absolute level
and statistical properties of the systematic errors on weak lensing shear
measurements due to the most important physical effects in the LSST system via
high fidelity ray-tracing simulations. We identify and isolate the different
sources of algorithm-independent, \textit{additive} systematic errors on shear
measurements for LSST and predict their impact on the final cosmic shear
measurements using conventional weak lensing analysis techniques. We find that
the main source of the errors comes from an inability to adequately
characterise the atmospheric point spread function (PSF) due to its high
frequency spatial variation on angular scales smaller than in the
single short exposures, which propagates into a spurious shear correlation
function at the -- level on these scales. With the large
multi-epoch dataset that will be acquired by LSST, the stochastic errors
average out, bringing the final spurious shear correlation function to a level
very close to the statistical errors. Our results imply that the cosmological
constraints from LSST will not be severely limited by these
algorithm-independent, additive systematic effects.Comment: 22 pages, 12 figures, accepted by MNRA
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