Measurements of Absolute Hadronic Branching Fractions of D Mesons

Using e+e- collisions recorded at the psi(3770) resonance with the CLEO-c detector at the Cornell Electron Storage Ring, we determine absolute hadronic branching fractions of charged and neutral D mesons. Among measurements for both Cabibbo-favored and Cabibbo-suppressed modes, we obtain reference branching fractions B(D0 -> 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. Using a determination of the integrated luminosity, we also extract the e+e- -> DDbar cross sections.Comment: 3 pages, to appear in the Proceedings of PANIC'05 (Particles and Nuclei International Conference), Santa Fe, NM, October 24-28 200

Comment on "Analysis of the Spatial Distribution between Successive Earthquakes" by Davidsen and Paczuski

By analyzing a southern California earthquake catalog, Davidsen and Paczuski [Phys. Rev. Lett. 94, 048501 (2005)] claim to have found evidence contradicting the theory of aftershock zone scaling in favor of scale-free statistics. We present four elements showing that Davidsen and Paczuski's results may be insensitive to the existence of physical length scales associated with aftershock zones or mainshock rupture lengths, so that their claim is unsubstantiated. (i) Their exponent smaller than 1 for a pdf implies that the power law statistics they report is at best an intermediate asymptotic; (ii) their power law is not robust to the removal of 6 months of data around Landers earthquake within a period of 17 years; (iii) the same analysis for Japan and northern California shows no evidence of robust power laws; (iv) a statistical model of earthquake triggering that explicitely obeys aftershock zone scaling can reproduce the observed histogram of Davidsen and Paczuski, demonstrating that their statistic may not be sensitive to the presence of characteristic scales associated with earthquake triggering