96 research outputs found
The Two-mass Contribution to the Three-Loop Gluonic Operator Matrix Element
We calculate the two-mass QCD contributions to the massive operator matrix
element at in analytic form in Mellin
- and -space, maintaining the complete dependence on the heavy quark mass
ratio. These terms are important ingredients for the matching relations of the
variable flavor number scheme in the presence of two heavy quark flavors, such
as charm and bottom. In Mellin -space the result is given in the form of
nested harmonic, generalized harmonic, cyclotomic and binomial sums, with
arguments depending on the mass ratio. The Mellin inversion of these quantities
to -space gives rise to generalized iterated integrals with square root
valued letters in the alphabet, depending on the mass ratio as well. Numerical
results are presented.Comment: 99 pages LATEX, 2 Figure
The massive 3-loop operator matrix elements with two masses and the generalized variable flavor number scheme
We report on our latest results in the calculation of the two--mass
contributions to 3--loop operator matrix elements (OMEs). These OMEs are needed
to compute the corresponding contributions to the deep-inealstic scattering
structure functions and to generalize the variable flavor number scheme by
including both charm and bottom quarks. We present the results for the
non-singlet and OMEs, and compare the size of their contribution
relative to the single mass case. Results for the gluonic OME are
given in the physical case, going beyond those presented in a previous
publication where scalar diagrams were computed. We also discuss our recently
published two--mass contribution to the pure singlet OME, and present an
alternative method of calculating the corresponding diagrams.Comment: 20 pages Latex, 5 Figures, different style file
Effect of temperature on pollen tube kinetics and dynamics in sweet cherry, Prunus avium (Rosaceae)
The article is available at:
http://www.amjbot.org/cgi/content/full/91/4/558Prevailing ambient temperature during the reproductive phase is one of several important factors for seed and fruit set in different plant species, and its consequences on reproductive success may increase with global warming. The effect of temperature on pollen performance was evaluated in sweet cherry (Prunus avium L.), comparing as pollen donors two cultivars that differ in their adaptation to temperature. âSunburstâ is a cultivar that originated in Canada with a pedigree of cultivars from Northern Europe, while âCristobalinaâ is a cultivar native to southeast Spain, adapted to warmer conditions. Temperature effects were tested either in controlled-temperature chambers or in the field in a plastic cage. In both genotypes, an increase in temperature reduced pollen germination, but accelerated pollen tube growth. However, a different genotypic response, which reflected the overall adaptation of the pollen donor, was obtained for pollen tube dynamics, expressed as the census of the microgametophyte population that successfully reached the base of the style. While both cultivars performed similarly at 20°C, the microgametophyte population was reduced at 30°C for Sunburst and at 10°C for Cristobalina. These results indicate a differential genotypic response to temperature during the reproductive phase, which could be important in terms of the time needed for a plant species to adapt to rapid temperature changes.A. H. was supported by an AECI and an SIA-DGA fellowship, and financial support for this work was provided by INIA (project grant RTA 01-103).Peer reviewe
ViewPoint Oriented Software Development
In this paper we propose a new approach to software development which explicitly avoids the use of a single representation scheme or common schema. Instead, multiple ViewPoints are utilised to partition the domain information, the development method and the formal representations used to express software specifications. System specifications and methods are then described as configurations of related ViewPoints. This partitioning of knowledge facilitates distributed development, the use of multiple representation schemes and scalability. Furthermore, the approach is general, covering all phases of the software process from requirements to evolution. This paper motivates and systematically characterises the concept of a "ViewPoint", illustrating the concepts using a simplified example
O ( α ) polarized heavy flavor corrections to deep-inelastic scattering at Q ⫠m
We calculate the quarkonic O(α) massive operator matrix elements A (N),A(N) and A,(N) for the twistâ2 operators and the associated heavy flavor Wilson coefficients in polarized deeply inelastic scattering in the region Q â« m to O(Δ) in the case of the inclusive heavy flavor contributions. The evaluation is performed in Mellin space, without applying the integration-by-parts method. The result is given in terms of harmonic sums. This leads to a significant compactification of the operator matrix elements and massive Wilson coefficients in the region Q â« m derived previously in [1], which we partly confirm, and also partly correct. The results allow to determine the heavy flavor Wilson coefficients for g(x, Q) to O(α ) for all but the power suppressed terms â (m/Q) , k â„ 1. The results in momentum fraction z-space are also presented. We also discuss the small x effects in the polarized case. Numerical results are presented. We also compute the gluonic matching coefficients in the twoâmass variable flavor number scheme to O(Δ)
PCV26 PRACTICE PATTERNS AND QUALITY OF LIFE IN PATIENTS WITH ACUTE CORONARY SYNDROME IN THE NORDIC COUNTRIES: RESULTS FROM THE ANTIPLATELET TREATMENT OBSERVATIONAL REGISTRY II (APTOR II)
) Polarized Heavy Flavor Corrections}to Deep-Inelastic Scattering at
We calculate the quarkonic massive operator matrix elements
and
for the twist--2 operators and the associated heavy flavor Wilson coefficients
in polarized deeply inelastic scattering in the region to
in the case of the inclusive heavy flavor contributions. The
evaluation is performed in Mellin space, without applying the
integration-by-parts method. The result is given in terms of harmonic sums.
This leads to a significant compactification of the operator matrix elements
and massive Wilson coefficients in the region derived previously
in \cite{BUZA2}, which we partly confirm, and also partly correct. The results
allow to determine the heavy flavor Wilson coefficients for to
for all but the power suppressed terms . The results in momentum fraction -space are also presented. We also
discuss the small effects in the polarized case. Numerical results are
presented. We also compute the gluonic matching coefficients in the two--mass
variable flavor number scheme to .Comment: 58 pages Latex, 12 Figure
The Two-mass Contribution to the Three-Loop Polarized Operator Matrix Element
We compute the two-mass contributions to the polarized massive operator
matrix element at third order in the strong coupling constant
in Quantum Chromodynamics analytically. These corrections are
important ingredients for the matching relations in the variable flavor number
scheme and for the calculation of Wilson coefficients in deep--inelastic
scattering in the asymptotic regime . The analytic result
is expressed in terms of nested harmonic, generalized harmonic, cyclotomic and
binomial sums in -space and by iterated integrals involving square-root
valued arguments in space, as functions of the mass ratio. Numerical
results are presented. New two--scale iterative integrals are calculated.Comment: 59 Latex, 2 figure
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