244 research outputs found
The Energy Dependence of the Saturation Scale
At low , in deep inelastic scattering, the photon
fluctuates into a vector state that interacts via two gluons with
the proton. The energy dependence is determined by the saturation scale, in our
approach given by . Imposing DGLAP
evolution, we find in agreement with the
model-independent analysis of the HERA data. Different values of the exponent
are correlated with different ratios of the longitudinal to transverse
structure function. This stresses the need for experiments to separate
longitudinal and transverse contributions in deep inelastic scattering.Comment: To appear in the proceedings of "PHOTON2005 International Conference
on the Structure and Interactions of the Photon including the 16th
International Workshop on Photon-Photon Collisions", Warsaw, 200
A Design Method for Pin Holding Type Jig
Multi-item flexible manufacturing systems have been spread to correspond the short life-cycle and the diversification of products. Part handling plays an important role to operate multi-functional robot efficiently in these systems, and many jigs are widely used to hold a part. They should be exchanged at once according to changing products. In this paper, we propose a pin jig which holds a part with two pins, and design method of the position, length and diameter of those pins for a cylindrical part. This jig has the following characteristics. As a surface of the jig is inclined to use gravity, the part can be fixed without any external forces. Therefore the structure of jig becomes simple, and loading and unloading of a part becomes easy for a robot hand
J/Psi photo- and electroproduction, the saturation scale and the gluon structure function
Our approach to low-x deep inelastic scattering based on the ell-perp
factorization of perturbative QCD (the color-dipole picture) yields
parameter-free absolute predictions for J/Psi production. The connection of
J/Psi production to the low-x saturation scale and to the gluon structure
function is clarified.Comment: 14 pages with 4 figures, with some comments on skewness etc adde
On e+e- --> W+W- --> 4f(+gamma) at LEP2
The results on e+e- --> W+W- --> 4f(+gamma) obtained by different groups are
compared with each other. Differences in the results for the total cross
section of up to about 0.6% are traced back to different ways of implementing
the double-pole approximation.Comment: 11 pages, late
The Color Dipole Picture and the ratio of R(W, Q) = sigma L/sigma T
The transverse size of q q-bar fluctuations of the longitudinal photon is
reduced relative to the transverse size of q q-bar fluctuations of the
transverse photon. This implies R(W2, Q2) = 0.375 or, equivalently, FL/F2 =
0.27 at x<<0.1 and Q2 sufficiently large, while R(W2, Q2) = 0.5, if this effect
is not taken into account. Forthcoming experimental data from HERA will allow
to test this prediction.Comment: 13 pages, 1 figur
Fractional time differential equations as a singular limit of the Kobayashi-Warren-Carter system
This paper is concerned with a singular limit of the Kobayashi-Warren-Carter
system, a phase field system modelling the evolutions of structures of grains.
Under a suitable scaling, the limit system is formally derived when the
interface thickness parameter tends to zero. Different from many other
problems, it turns out that the limit system is a system involving fractional
time derivatives, although the original system is a simple gradient flow. A
rigorous derivation is given when the problem is reduced to a gradient flow of
a single-well Modica-Mortola functional in a one-dimensional setting.Comment: 24 page
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