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 $\sim$ 20,000 square degrees of sky in six filter bands every few nights, bringing the final survey depth to $r\sim27.5$, 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 $\sim10'$ in the single short exposures, which propagates into a spurious shear correlation function at the $10^{-4}$--$10^{-3}$ 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