9,492 research outputs found
On the Behavior of F2 and its Logarithmic Slopes
It is shown that the CKMT model for the nucleon structure function F2, taken
as the initial condition for the NLO evolution equations in perturbative QCD,
provides a good description of the HERA data when presented in the form of the
logarithmic slopes of F2 vs x and Q2 (Caldwell-plot), in the whole available
kinematic ranges. Also the results obtained for the behavior of the gluon
component of a nucleon are presented.Comment: 16 pages, 10 figure
Improved bounds for the number of forests and acyclic orientations in the square lattice
In a recent paper Merino and Welsh (1999) studied several counting problems on the square lattice . The authors gave the following bounds for the asymptotics of , the number of forests of , and , the number of acyclic orientations of : and .
In this paper we improve these bounds as follows: and . We obtain this by developing a method for computing the Tutte polynomial of the square lattice and other related graphs based on transfer matrices
Discrete variational integrators and optimal control theory
A geometric derivation of numerical integrators for optimal control problems
is proposed. It is based in the classical technique of generating functions
adapted to the special features of optimal control problems.Comment: 17 page
Geometric numerical integration of nonholonomic systems and optimal control problems
A geometric derivation of numerical integrators for nonholonomic systems and
optimal control problems is obtained. It is based in the classical technique of
generating functions adapted to the special features of nonholonomic systems
and optimal control problems.Comment: 6 pages, 1 figure. Submitted to IFAC Workshop on Lagrangian and
Hamiltonian Methods for Nonlinear Control, Sevilla 200
Tulczyjew's triples and lagrangian submanifolds in classical field theories
In this paper the notion of Tulczyjew's triples in classical mechanics is
extended to classical field theories, using the so-called multisymplectic
formalism, and a convenient notion of lagrangian submanifold in multisymplectic
geometry. Accordingly, the dynamical equations are interpreted as the local
equations defining these lagrangian submanifolds.Comment: 29 page
On the Moyal deformation of Nahm Equations in seven dimensions
We show how the reduced (anti-)self-dual Yang-Mills equations in seven
dimensions described by the Nahm equations can be carried over to the
Weyl-Wigner-Moyal formalism. In the process some new solutions for the cases of
gauge groups SU(2) and SL(2,R) are explicitly obtained.Comment: 16+1 pages, LaTeX, no figure
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