Reply to Comment on ``Determination of pion-baryon coupling constants from QCD sum rules''

In response to Kim's comment (nucl-th/9903040) on the sum rules for pion-baryon coupling constants obtained in hep-ph/9512259 and hep-ph/9606471, we point out that our treatment of the continuum is consistent with duality and with the fact that the correlator in the presence of an external meson or field should be represented by a double dispersion relation.Comment: 5 pages (RevTeX), reply to nucl-th/990304

Microwave Spectroscopy of a Cooper-Pair Transistor Coupled to a Lumped-Element Resonator

We have studied the microwave response of a single Cooper-pair transistor (CPT) coupled to a lumped-element microwave resonator. The resonance frequency of this circuit, $f_{r}$, was measured as a function of the charge $n_{g}$ induced on the CPT island by the gate electrode, and the phase difference across the CPT, $\phi_{B}$, which was controlled by the magnetic flux in the superconducting loop containing the CPT. The observed $f_{r}(n_{g},\phi_{B})$ dependences reflect the variations of the CPT Josephson inductance with $n_{g}$ and $\phi_{B}$ as well as the CPT excitation when the microwaves induce transitions between different quantum states of the CPT. The results are in excellent agreement with our simulations based on the numerical diagonalization of the circuit Hamiltonian. This agreement over the whole range of $n_{g}$ and $\phi_{B}$ is unexpected, because the relevant energies vary widely, from 0.1K to 3K. The observed strong dependence $f_{r}(n_{g},\phi_{B})$ near the resonance excitation of the CPT provides a tool for sensitive charge measurements.Comment: 10 pages, 6 figure

A New Technique for Measuring the Strangemess Content of the Proton on the Lattice

A new technique for computing the strangeness content of the proton on the lattice is described. It is applied to the calculation of the strange quark contribution to the proton's spin, specifically to the evaluation of the proton matrix element of the strange quark axial current. Preliminary results are not in disagreement with the EMC experiment. NOTE: This paper is available only in postscript form.Comment: 8 pages, figures included in the text, all in postscrip

Low-Lying Nucleons from Chirally Improved Fermions

We report on our preliminary results on the low-lying excited nucleon spectra which we obtain through a variational basis formed with three different interpolators.Comment: Contributed to Lattice 2003(spectrum), Tsukub

Renormalization Group Improved Heavy Quark Production in Polarized \gamma \gamma Collisions

The experimental determination of the partial width $\Gamma (H \longrightarrow \gamma \gamma)$ of an intermediate mass Higgs is among the most important measurements at a future photon photon collider. Recently it was shown that large non-Sudakov as well as Sudakov double logarithmic (DL) corrections can be summed to all orders in the background process $\gamma \gamma (J_z=0) \longrightarrow q \bar{q}$. It was found that positivity and stability of the cross section was only restored at the four-loop level. One remaining large source of uncertainty stems from the fact that the scale of the strong coupling is unspecified within the double logarithmic approximation. In this paper we include the leading and next-to-leading order running coupling to all orders. We thus remove the inherent scale uncertainty of both the exact one-loop and all-orders DL result without encountering any Landau-pole singularities. The effect is significant and, for the non-Sudakov form factor, is found to correspond to an effective scale of roughly $\alpha_s(9m_q^2)$.Comment: 23 pages, 10 eps-figure

The nucleon wave function at the origin

We calculate the next-to-leading order perturbative corrections to the SVZ sum rules for the coupling f_N, the nucleon leading twist wave function at the origin. The results are compared to the established Ioffe sum rules and also to lattice QCD simulations.Comment: 8 pages, 3 figures, LaTeX; updated plots, refined error estimation; accepted for publication in PL

Testing QCD Sum Rule Techniques on the Lattice

Results for the first test of the ``crude'' QCD continuum model, commonly used in QCD Sum Rule analyses, are presented for baryon correlation functions. The QCD continuum model is found to effectively account for excited state contributions to the short-time regime of two-point correlation functions and allows the isolation of ground state properties. Confusion in the literature surrounding the physics represented in point-to-point correlation functions is also addressed. These results justify the use of the ``crude'' QCD continuum model and lend credence to the results of rigorous QCD Sum Rule analyses.Comment: Discussion of systematic uncertainties augmente

TbGT8 is a bifunctional glycosyltransferase that elaborates<em> N</em>-linked glycans on a protein phosphatase AcP115 and a GPI-anchor modifying glycan in <em>Trypanosoma brucei</em>

AbstractThe procyclic form of Trypanosoma brucei expresses procyclin surface glycoproteins with unusual glycosylphosphatidylinositol-anchor side chain structures that contain branched N-acetyllactosamine and lacto-N-biose units. The glycosyltransferase TbGT8 is involved in the synthesis of the branched side chain through its UDP-GlcNAc: βGal β1-3N-acetylglucosaminyltransferase activity. Here, we explored the role of TbGT8 in the mammalian bloodstream form of the parasite with a tetracycline-inducible conditional null T. brucei mutant for TbGT8. Under non-permissive conditions, the mutant showed significantly reduced binding to tomato lectin, which recognizes poly-N-acetyllactosamine-containing glycans. Lectin pull-down assays revealed differences between the wild type and TbGT8 null-mutant T. brucei, notably the absence of a broad protein band with an approximate molecular weight of 110kDa in the mutant lysate. Proteomic analysis revealed that the band contained several glycoproteins, including the acidic ecto-protein phosphatase AcP115, a stage-specific glycoprotein in the bloodstream form of T. brucei. Western blotting with an anti-AcP115 antibody revealed that AcP115 was approximately 10kDa smaller in the mutant. Enzymatic de-N-glycosylation demonstrated that the underlying protein cores were the same, suggesting that the 10-kDa difference was due to differences in N-linked glycans. Immunofluorescence microscopy revealed the colocalization of hemagglutinin epitope-tagged TbGT8 and the Golgi-associated protein GRASP. These data suggest that TbGT8 is involved in the construction of complex poly-N-acetyllactosamine-containing type N-linked and GPI-linked glycans in the Golgi of the bloodstream and procyclic parasite forms, respectively