Learn More
The U.S. Food and Drug Administration (FDA) attempts to identify and understand new risks associated with medical device use; communicate information and recommendations to device users; help manage known risks by providing strategies to facilitate safe use; guide manufacturers to improve design, labeling, and training to address known risks; and guide(More)
The correlation coefficients a, A, and B in neutron beta decay are proportional to the ratio of the axial-vector-to-vector weak coupling constants, gA/gV, to leading recoil order. With the advent of the next generation of neutron-decay experiments, the recoil-order corrections to these expressions become experimentally accessible, admitting a plurality of(More)
The Sivers mechanism for the single-spin asymmetry in unpolarized lepton scattering from a transversely polarized nucleon is driven by the orbital angular momentum carried by its quark and gluon constituents, combined with QCD final-state interactions. Both quark and gluon mechanisms can generate such a single-spin asymmetry, though only the quark mechanism(More)
We examine the role of B 0 (¯ B 0) → σπ 0 → π + π − π 0 decay in the Dalitz plot analysis of B 0 (¯ B 0) → ρπ → π + π − π 0 decays, employed to extract the CKM parameter α. The σπ channel is significant because it can break the relationship between the penguin contributions in B → ρ 0 π 0 , B → ρ + π − , and B → ρ − π + decays consequent to an assumption of(More)
In the analysis of ǫ ′ /ǫ it has been traditional to consider the isospin-breaking effects arising from electroweak-penguin contributions and from π 0-η, η ′ mixing, yet additional isospin-violating effects exist. In particular, we study the isospin violation which arises from the u-d quark mass difference in the hadronization of the gluonic penguin(More)
Isospin-breaking effects, in particular those associated with electroweak-penguin contributions and π 0-η, η ′ mixing, have long been known to affect the Standard Model prediction of ǫ ′ /ǫ in a significant manner. We have found an heretofore uncon-sidered isospin-violating effect of importance; namely, the u-d quark mass difference can spawn |∆I| = 3/2(More)
We determine the magnitude, phase, and s-dependence of ρ-ω " mixing " in the pion form factor in the time-like region through fits to e + e − → π + π − data. The associated systematic errors in these quantities, arising from the functional form used to fit the ρ resonance, are small. The systematic errors in the ρ mass and width, however, are larger than(More)
The quark exchange model is a simple realization of an adiabatic approximation to the strong-coupling limit of Quantum Chromodynamics (QCD): the quarks always coalesce into the lowest energy set of flux tubes. Nuclear matter is thus modeled in terms of its quarks. We wish to study the correlations imposed by total wavefunction antisymmetry when color(More)
The Dalitz decay π 0 → e + e − γ has been measured in the γp → π 0 p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the π 0 electromagnetic transition form factor, a π = 0.030 ± 0.010 tot , is in agreement with existing measurements of this decay and with recent theoretical(More)