1,463 research outputs found
Determination of the strange quark mass from Cabibbo-suppressed tau decays with resummed perturbation theory in an effective scheme
We present an analysis of the m_s^2-corrections to Cabibbo-suppressed tau
lepton decays employing contour improved resummation within an effective scheme
which is an essential new feature as compared to previous analyses. The whole
perturbative QCD dynamics of the tau-system is described by the beta-function
of the effective coupling constant and by two gamma-functions for the effective
mass parameters of the strange quark in different spin channels. We analyze the
stability of our results with regard to high-order terms in the perturbative
expansion of the renormalization group functions. A numerical value for the
strange quark mass in the MS scheme is extracted m_s(M_\tau)=130\pm 27_{exp}\pm
9_{th} MeV. After running to the scale 1 GeV this translates into m_s(1
GeV)=176 \pm 37_{exp}\pm 13_{th} MeV.Comment: 32 pages, latex, 4 postscript figures, revised version to appear in
European Physical Journal C, discussion of the choice of the moments added,
some errors correcte
Asymptotic structure of perturbative series for lepton decay observables: corrections
In a previous paper we performed an analysis of asymptotic structure of
perturbation theory series for semileptonic -lepton decays in massless
limit. We extend our analysis to the Cabibbo suppressed decay
modes of the lepton. In particular we address the problem of
corrections to theoretical formulas. The properties of the asymptotic behavior
of the finite order perturbation theory series for the coefficient functions of
the corrections are studied.Comment: 25 page
Asymptotic structure of perturbative series for tau lepton observables
We analyze tau lepton decay observables, namely moments of the hadronic
spectral density in the finite energy interval (0,M_\tau), within finite order
perturbation theory including \alpha_s^4 corrections. The start of asymptotic
growth of perturbation theory series is found at this order in a scheme
invariant manner. We establish the ultimate accuracy of finite order
perturbation theory predictions and discuss the construction of optimal
observables.Comment: 21 page
A Purification of venom phosphodiesterase
For purposes of analysis of polynucleotides, it is desirable to have a phosphodiesterase, substantially free of 5-nucleotidase or other phosphatase activity. The presence of a phosphodiesterase in a wide variety of
snake venoms was demonstrated by Gullan and Jackson (1). These venoms were found also to contain a potent 5-nucleotidase, but were free of alkaline phosphatase activity. Hurst and Butler (2) found that certain samples of Russell's viper venom were nearly free of 5-nucleotidase activity, while retaining potent phosphodiesterase action. By a chromatographic procedure, involving the use of cellulose columns, they were able to reduce the 5-nucleotidase activity of rattlesnake venom, relative to its phosphodiesterase activity, and to obtain fractions nearly comparable to the viper venom
A Deoxyribonuclease from Calf Spleen. II. Mode of Action
When highly polymerized deoxyribonucleic acid is digested with pancreatic DNase and the digest further degraded with phosphodiesterase from intestinal mucose or snake venom, the mononucleotides formed are 5'-phosphates. Since a digest prepared in this manner with a purified venom diesterase contains only 5'-mononucleotides and practically
no nucleosides or polynucleotides, the pancreatic DNase must form only polynucleotides with 5' monoesterified phosphate end groups. Recently the enzymatic synthesis of polydeoxyribonucleotides from eoxyribonucleoside 5'-triphosphates has been demonstrated. Thus both enzymatic synthesis and degradation of deoxyribonucleic acids have as yet involved only derivatives with 5'-monoesterified phosphate
A Deoxyribonuclease from Calf Spleen: I Purification and Properties
The deoxyribonucleases1 of animal tissues are of two types which are readily distinguishable by the conditions necessary for activity on their substrate, DNA. The pancreatic DNase, which has been crystallized by Kunitz (1), is active in neutral solution in the presence of magnesium or certain other divalent cations (2). The DN ase predominant in most other tissues is active at a lower pH, in the presence of adequate ionic strength, but does not specifically require divalent ions
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