19,735 research outputs found
An Algorithm to Construct Groebner Bases for Solving Integration by Parts Relations
This paper is a detailed description of an algorithm based on a generalized
Buchberger algorithm for constructing Groebner-type bases associated with
polynomials of shift operators. The algorithm is used for calculating Feynman
integrals and has proven itself efficient in several complicated cases.Comment: LaTeX, 9 page
Chiral color symmetry and possible -boson effects at the Tevatron and LHC
A gauge model with chiral color symmetry is considered and possible effects
of the color -boson octet predicted by this symmetry are investigated in
dependence on two free parameters, the mixing angle and mass
. The allowed region in the plane is found from the
Tevatron data on the cross section and forward-backward
asymmetry of the production. The mass limits
for the -boson are shown to be stronger than those for the axigluon. A
possible effect of the -boson on the production at the LHC is
discussed and the mass limits providing for the -boson evidence at the LHC
are estimated in dependence on .Comment: 11 pages, 2 figures, accepted for publication in Modern Physics
Letters
Q2237+0305 source structure and dimensions from light curves simulation
Assuming a two-component quasar structure model consisting of a central
compact source and an extended outer feature, we produce microlensing
simulations for a population of star-like objects in the lens galaxy. Such a
model is a simplified version of that adopted to explain the brightness
variations observed in Q0957 (Schild & Vakulik 2003). The microlensing light
curves generated for a range of source parameters were compared to the light
curves obtained in the framework of the OGLE program. With a large number of
trials we built, in the domain of the source structure parameters, probability
distributions to find "good" realizations of light curves. The values of the
source parameters which provide the maximum of the joint probability
distribution calculated for all the image components, have been accepted as
estimates for the source structure parameters. The results favour the
two-component model of the quasar brightness structure over a single compact
central source model, and in general the simulations confirm the Schild-Vakulik
model that previously described successfully the microlensing and other
properties of Q0957. Adopting 3300 km/s for the transverse velocity of the
source, the effective size of the central source was determined to be about
2x10^15 cm, and Epsilon =2 was obtained for the ratio of the integral
luminosity of the outer feature to that of the central source.Comment: 7 pages, 4 figures, LaTe
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