Azimuthal correlation between the (p⃗l,p⃗Xb)(\vec{p}_l,\vec{p}_{X_b}) and (p⃗l,P⃗t)(\vec{p}_l,\vec{P}_t) planes in the semileptonic rest frame decay of a polarized top quark: An O(αs)O(\alpha_s) effect

The azimuthal correlation between the planes formed by the vectors $(\vec{p}_\ell,\vec{p}_{X_b})$ and $(\vec{p}_\ell,\vec{P}_t)$ in the semileptonic rest frame decay of a polarized top quark $t(\uparrow) \to X_b + l^+ + \nu_\ell$ belongs to a class of polarization observables involving the top quark which vanish at the Born term level in the standard model. We determine the next--to--leading order QCD corrections to the afore-mentioned azimuthal correlation and compare the result to the corresponding contribution of a non--standard--model right--chiral quark current.Comment: latex, 12 pages with 2 figures in the text, typos removed,comment and references added, replaced with published versio

On the direction of transcription of cloned genes in Neurospora crassa.

On the direction of transcription of cloned genes in Neurospora crassa

Co-regulation of two tandem genes by one blue-light element in Neurospora crassa

Many genes of Neurospora crassa are regulated by blue light: al-1 (Schmidhauser et al. 1990 Mol. Cell. Biol. 10:5064-5070), al-2 (Lauter, Schmidhauser, Yanofsky, Russo unpublished), al-3 (Nelson et al. 1989 Mol. Cell. Biol. 9:1271-1276), bli-3, bli-4, bli-7, bli-13 (Sommer et al. 1989 NAR 17:5713-5723). For none of these genes are the blue light cis-regulatory sequences (blue-light elements, BE) known. Here we report the presence of such BE in front of bli-4

Meson Decay Constants from Isospin Mass Splittings in the Quark Model

Decay constants of $D$ and $B$ mesons are estimated within the framework of a heavy-quark approach using measured isospin mass splittings in the $D$, $D^*$, and $B$ states to isolate the electromagnetic hyperfine interaction between quarks. The values $f_D = (262 \pm 29)$ MeV and $f_B = (160 \pm 17)$ MeV are obtained. Only experimental errors are given; possible theoretical ambiguities, and suggestions for reducing them, are noted.Comment: 7 pages, LaTeX, EFI-92-3

Renormalization of the QED of second order spin 1/2 fermions

In this work we study the renormalization of the electrodynamics of spin 1/2 fermions in the Poincar\'e projector formalism which is second order in the derivatives of the fields. We analyze the superficial degree of divergence of the vertex functions of this theory, calculate at one-loop level the vacuum polarization, fermion self-energy and \gamma-fermion-fermion vertex function and the divergent piece of the one-loop contributions to the \gamma-\gamma-fermion-fermion vertex function. It is shown that these functions are renormalizable independently of the value of the gyromagnetic factor g which is a free parameter of the theory. We find a photon propagator and a running coupling constant \alpha (q^2) that depend on the value of g. The magnetic moment form factor contains a divergence associated to g which disappears for g=2 but in general requires the coupling g to be renormalized. A suitable choice of the renormalization condition for the magnetic form factor yields the one loop finite correction \Delta{g}=g\alpha/2\pi. For a particle with g=2 we recover results of Dirac theory for the photon propagator, the running of \alpha (q^2) and the one-loop corrections to the gyromagnetic factor.Comment: 20 pages including 6 figures. Rewritten paper, results unchanged, version accepted in PRD. Results written in terms of Passarino-Veltman scalar integral

On the Early History of Current Algebra

The history of Current Algebra is reviewed up to the appearance of the Adler-Weisberger sum rule. Particular emphasis is given to the role current algebra played for the historical struggle in strong interaction physics of elementary particles between the S-matrix approach based on dispersion relations and field theory. The question whether there are fundamental particles or all hadrons are bound or resonant states of one another played an important role in this struggle and is thus also regarded.Comment: 17 page

Hepatitis C virus cell-cell transmission and resistance to direct-acting antiviral agents

Hepatitis C virus (HCV) is transmitted between hepatocytes via classical cell entry but also uses direct cell-cell transfer to infect neighboring hepatocytes. Viral cell-cell transmission has been shown to play an important role in viral persistence allowing evasion from neutralizing antibodies. In contrast, the role of HCV cell-cell transmission for antiviral resistance is unknown. Aiming to address this question we investigated the phenotype of HCV strains exhibiting resistance to direct-acting antivirals (DAAs) in state-of-the-art model systems for cell-cell transmission and spread. Using HCV genotype 2 as a model virus, we show that cell-cell transmission is the main route of viral spread of DAA-resistant HCV. Cell-cell transmission of DAA-resistant viruses results in viral persistence and thus hampers viral eradication. We also show that blocking cell-cell transmission using host-targeting entry inhibitors (HTEIs) was highly effective in inhibiting viral dissemination of resistant genotype 2 viruses. Combining HTEIs with DAAs prevented antiviral resistance and led to rapid elimination of the virus in cell culture model. In conclusion, our work provides evidence that cell-cell transmission plays an important role in dissemination and maintenance of resistant variants in cell culture models. Blocking virus cell-cell transmission prevents emergence of drug resistance in persistent viral infection including resistance to HCV DAAs