Renormalization of B-meson distribution amplitudes

We summarize a recent calculation of the evolution kernels of the two-particle B-meson distribution amplitudes $\phi_+$ and $\phi_-$ taking into account three-particle contributions. In addition to a few phenomenological comments, we give as a new result the evolution kernel of the combination of three-particle distribution amplitudes $\Psi_A-\Psi_V$ and confirm constraints on $\phi_+$ and $\phi_-$ derived from the light-quark equation of motion.Comment: 7 pages, 2 figures. Contribution to the proceedings of the Int. Workshop on Effective Field Theories: from the pion to the upsilon. Feb. 2009. Valencia, Spai

BELLE Data on the π0γ∗γ\pi^0 \gamma* \gamma Form Factor: A Game Changer?

We extend our analysis of the $\pi^0\gamma^*\gamma$ form factor by including a comparison with the new BELLE data. The necessity of new precision measurements in a broad interval of momentum transfers is emphasized.Comment: 4 pages, 3 figures. Addendum to Phys. Rev. D 83, 054020 (2011

A Comparison and Analysis of Detection Methods for the Measurement of Production in a Boundary Layer

Two hot films and dye visualizations have been employed, simultaneously, in a turbulent boundary layer to explore the relations among visual observations and five kinds of detection methods using conditional sampling. The results show that all methods correlate positively with each other, but not with high enough values of correlation coefficients to indicate true correspondence between any two thus far studied. Moreover, none of the detection methods devised to date indicate a plateau in number of events as a function of trigger threshold. The results also provide additional information on several other matters: (i) the relationship of outward motions from the wall (bursts) to inward motions (sweeps); (ii) further details on the time and space location of periods of high uv-product with respect to the visual models and to fluctuation hodograph quadrant, and (iii) some data bearing on the transfer of energy in the frequency domain during turbulence production (cascade processes). The present paper emphasizes the relations among the various detection methods and visual observations during intervals of high uv-product; other results are reported in more detail elsewhere

Current Investigations of Turbulent Shear

The paper covers first a short review of the history of research on turbulent shear and second a description of current experiments which may lead to further understanding. The first portion categorizes the kinds of data which have been taken and discusses what can be learned from each. It then summarizes what is firmly established concerning the nature of turbulent shear, mostly from work of the past decade. A description of the several interpretations of these data under theoretic study by current leading researchers is then given. The second portion of the paper discusses the extraordinarily difficult problem of identifying and measuring the actual production of turbulence in a boundary layer. The difficulties arise from the fact that production is a partly-coherent, intermittent process buried in relatively high amplitude noise. The measurement problems are discussed and a potential solution for the measurement of turbulence production with adequate accuracy is proposed

Three-particle contributions to the renormalisation of B-meson light-cone distribution amplitudes

We study light-cone distribution amplitudes of heavy-light systems, such as a B-meson. By an explicit computation, we determine how two-parton distribution amplitudes mix with three-parton ones at one loop: \phi_+ is shown to mix only into itself, whereas \phi_- mixes with the difference of three-parton distribution amplitudes \Psi_A-\Psi_V. We determine the corresponding anomalous dimension and we check the gauge independence of our result by considering a general covariant gauge. Finally, we comment on some implications of our result for phenomenological models of these distribution amplitudes.Comment: 21 pages, 5 figures, some comments and 2 references added, except for typesetting matches version published in JHE

Light Cone Sum Rules for the pi0-gamma*-gamma Form Factor Revisited

We provide a theoretical update of the calculations of the pi0-gamma*-gamma form factor in the LCSR framework, including up to six polynomials in the conformal expansion of the pion distribution amplitude and taking into account twist-six corrections related to the photon emission at large distances. The results are compared with the calculations of the B-> pi l nu decay and pion electromagnetic form factors in the same framework. Our conclusion is that the recent BaBar measurements of the pi0-gamma*-gamma form factor at large momentum transfers are consistent with QCD, although they do suggest that the pion DA may have more structure than usually assumed.Comment: 20 pages, 14 figures, 5 table

Renormalisation of heavy-light light ray operators

We calculate the renormalisation of different light ray operators with one light degree of freedom and a static heavy quark. Both $2\to2$- and $2\to3$-kernels are considered. A comparison with the light-light case suggests that the mixing with three-particle operators is solely governed by the light degrees of freedom. Additionally we show that conformal symmetry is already broken at the level of the one loop counterterms due to the additional UV-renormalisation of a cusp in the two contributing Wilson-lines. This general feature can be used to fix the $2\to2$-renormalisation kernels up to a constant. Some examples for applications of our results are given.Comment: 23 pages, 5 figures; v2: changed some wording, added a few references and one appendix concerning some subtleties related to gauge fixing and ghost terms; v3: clarified calculation in section 3.2., added an explicit calculation in section 5.2, corrected a few typos and one figure, added a few comments, results unchanged, except for typesetting matches version to appear in JHE

1,6-Cyclophellitol Cyclosulfates : A New Class of Irreversible Glycosidase Inhibitor

The essential biological roles played by glycosidases, coupled to the diverse therapeutic benefits of pharmacologically targeting these enzymes, provide considerable motivation for the development of new inhibitor classes. Cyclophellitol epoxides and aziridines are recently established covalent glycosidase inactivators. Inspired by the application of cyclic sulfates as electrophilic equivalents of epoxides in organic synthesis, we sought to test whether cyclophellitol cyclosulfates would similarly act as irreversible glycosidase inhibitors. Here we present the synthesis, conformational analysis, and application of novel 1,6-cyclophellitol cyclosulfates. We show that 1,6-epi-cyclophellitol cyclosulfate (α-cyclosulfate) is a rapidly reacting α-glucosidase inhibitor whose 4C1 chair conformation matches that adopted by α-glucosidase Michaelis complexes. The 1,6-cyclophellitol cyclosulfate (β-cyclosulfate) reacts more slowly, likely reflecting its conformational restrictions. Selective glycosidase inhibitors are invaluable as mechanistic probes and therapeutic agents, and we propose cyclophellitol cyclosulfates as a valuable new class of carbohydrate mimetics for application in these directions