932 research outputs found
Charm and Bottom Quark Masses from Perturbative QCD
Using a new result for the first moment of the hadronic production cross
section at order , and new data on the and
resonances for the charm quark, we determine the \msb masses of the
charm and bottom quarks to be GeV and
GeV. We assume that the continuum
contribution to the sum rules is adequately described by pQCD. While we observe
a large reduction of the perturbative error, the shifts induced by the
theoretical input are very small. The main change in the central value of
is related to the experimental data. On the other hand, the value of is
not changed by our calculation to the assumed precision.Comment: 5 pages, 2 figures, final version as publishe
Two-loop QCD corrections to the vector form factors for the heavy-quark photo-production
We review on the calculation of the heavy-quark photo-production vector form
factors, with the full dependence on the mass of the heavy-quark. The Feynman
diagrams are evaluated within the dimensional regularization scheme and
expressed in Laurent series of , where is the space-time
dimension. The coefficients of the expansion are expressed in terms of harmonic
polylogarithms. The numerical evaluation of the analytical formulas and the
threshold limit of our results are presented.Comment: Talk presented at the 11th International QCD Conference: QCD04,
Montpellier, France, 5-10 July 2004; 4 pages, 4 figure
Two-Loop Heavy-Flavor Contribution to Bhabha Scattering
We evaluate the two-loop QED corrections to the Bhabha scattering cross
section which involve the vacuum polarization by heavy fermions of arbitrary
mass m_f >> m_e. The results are valid for generic values of the Mandelstam
invariants s,t,u >> m_e^2.Comment: 13 pages, 6 figures. Equations in the appendix generalized to the
heavy-quark cas
Utilidad de la antitrombina III en la detección de coagulopatÃas asociadas a anemias hemolÃticas en animales crÃticos
En este trabajo se describe el resultado de la determinación de antitrombina III (ATIII) en veintitrés casos de anemia hemolÃtica asociada a estados de hipercoagulabilidad sanguÃnea. El 74% de los pacientes presentaron tasas bajas de ATIII y por lo tanto presentaban riesgos de desarrollar trombosis o coagulaciones intravasculares diseminadas (CID).
Characterization of femtosecond laser written waveguides for integrated biochemical sensing
Fluorescence detection is known to be one of the most sensitive among the different optical sensing techniques. This work focuses on excitation and detection of fluorescence emitted by DNA strands labeled with fluorescent dye molecules that can be excited at a specific wavelength. Excitation occurs via optical channel waveguides written with femtosecond laser pulses applied coplanar with a microfluidic channel on a glass chip. The waveguides are optically characterized in order to facilitate the design of sensing structures which can be applied for monitoring the spatial separation of biochemical\ud
species as a result of capillary electrophoresis
Two-Loop QCD Corrections to the Heavy Quark Form Factors: Axial Vector Contributions
We consider the Z Q Qbar vertex to second order in the QCD coupling for an
on-shell massive quark-antiquark pair and for arbitrary momentum transfer of
the Z boson. We present closed analytic expressions for the two
parity-violating form factors of that vertex at the two-loop level in QCD,
excluding the contributions from triangle diagrams. These form factors are
expressed in terms of 1-dimensional harmonic polylogarithms of maximum weight
4.Comment: 57 pages, 5 figures. All the results in Section 6 of the paper are
available in an electronic form in the file formulas.in
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