2,726 research outputs found
Constraints on "Second Order Fixed Point" QCD from the CCFR Data on Deep Inelastic Neutrino-Nucleon Scattering
The results of LO {\it Fixed point} QCD (FP-QCD) analysis of the CCFR data
for the nucleon structure function are presented. The
predictions of FP-QCD, in which the Callan-Symanzik function admits a
{\it second order} ultraviolet zero at are in good
agreement with the data. Constraints for the possible values of the
function parameter regulating how fast tends to its
asymptotic value are found from the data. The corresponding
values of are also determined. Having in mind our recent " First
order fixed point" QCD fit to the same data we conclude that in spite of the
high precision and the large kinematic range of the CCFR data they
cannot discriminate between QCD and FP-QCD predictions for .Comment: 8 pages, LaTe
One class of linear Fredholm integral equations with functionals and parameters
The theory of linear Fredholm integral-functional equations of the second
kind with linear functionals and with a parameter is considered. The necessary
and sufficient conditions are obtained for the coefficients of the equation and
those parameter values, in the nighbohood of which the equation has solutions.
The leading terms of the asymptotics of the solutions are constructed. The
constructive method is proposed for constructing a solution both in the regular
case and in the irregular one. In the regular case, the solution is constructed
as a Taylor series in powers of the parameter. In the irregular case, the
solution is constructed as a Laurent series in powers of the parameter.
Constructive theory and method is demonstrated on the model example
Extremal sequences of polynomial complexity
The joint spectral radius of a bounded set of real matrices is
defined to be the maximum possible exponential growth rate of products of
matrices drawn from that set. For a fixed set of matrices, a sequence of
matrices drawn from that set is called \emph{extremal} if the associated
sequence of partial products achieves this maximal rate of growth. An
influential conjecture of J. Lagarias and Y. Wang asked whether every finite
set of matrices admits an extremal sequence which is periodic. This is
equivalent to the assertion that every finite set of matrices admits an
extremal sequence with bounded subword complexity. Counterexamples were
subsequently constructed which have the property that every extremal sequence
has at least linear subword complexity. In this paper we extend this result to
show that for each integer , there exists a pair of square matrices
of dimension for which every extremal sequence has subword
complexity at least .Comment: 15 page
The Role of Higher Twist in Determining Polarized Parton Densities from DIS data
Different methods to extract the polarized parton densities from the world
polarized DIS data are considered. The higher twist corrections to
the spin dependent proton and neutron structure functions are found to be
non-negligible and important in the QCD analysis of the present experimental
data. Their role in determining the polarized parton densities in the framework
of the different approaches is discussed.Comment: To appear in the Proceedings of the Spin2004 Symposium, Trieste,
11-16 Oct 200
- …