1,487 research outputs found
Generalisation of DGLAP equations to massive partons
DGLAP evolution equations are modified in order to use all the quark families
in the full scale range, satisfying kinematical constraints and sumrules, thus
having complete continuity for the pdfs and observables. Some consequences of
this new approach are shown.Comment: 12 Pages and 5 Figure
A fast and precise method to solve the Altarelli-Parisi equations in x space
A numerical method to solve linear integro-differential equations is
presented. This method has been used to solve the QCD Altarelli-Parisi
evolution equations within the H1 Collaboration at DESY-Hamburg. Mathematical
aspects and numerical approximations are described. The precision of the method
is discussed.Comment: 18 pages, 4 figure
Magnetization of Mesoscopic Disordered Networks
We study the magnetic response of mesoscopic metallic isolated networks. We
calculate the average and typical magnetizations in the diffusive regime for
non-interacting electrons or in the first order Hartree-Fock approximation.
These quantities are related to the return probability for a diffusive particle
on the corresponding network. By solution of the diffusion equation on various
types of networks, including a ring with arms or an infinite square network, we
deduce the corresponding magnetizations. In the case of an infinite network,
the Hartree-Fock average magnetization stays finite in the thermodynamic limit.Comment: 4 pages, latex, 2 figure
A new global analysis of deep inelastic scattering data
A new QCD analysis of Deep Inelastic Scattering (DIS) data is presented. All
available neutrino and anti-neutrino cross sections are reanalysed and included
in the fit, along with charged-lepton DIS and Drell-Yan data. A massive
factorisation scheme is used to describe the charm component of the structure
functions. Next-to-leading order parton distribution functions are provided. In
particular, the strange sea density is determined with a higher accuracy with
respect to other global fits.Comment: 51 pages, 18 figure
Boundary conditions at the mobility edge
It is shown that the universal behavior of the spacing distribution of
nearest energy levels at the metal--insulator Anderson transition is indeed
dependent on the boundary conditions. The spectral rigidity also
depends on the boundary conditions but this dependence vanishes at high energy
. This implies that the multifractal exponent of the participation
ratio of wave functions in the bulk is not affected by the boundary conditions.Comment: 4 pages of revtex, new figures, new abstract, the text has been
changed: The large energy behavior of the number variance has been found to
be independent of the boundary condition
Spectral determinant on quantum graphs
We study the spectral determinant of the Laplacian on finite graphs
characterized by their number of vertices V and of bonds B. We present a path
integral derivation which leads to two equivalent expressions of the spectral
determinant of the Laplacian either in terms of a V x V vertex matrix or a 2B x
2B link matrix that couples the arcs (oriented bonds) together. This latter
expression allows us to rewrite the spectral determinant as an infinite product
of contributions of periodic orbits on the graph. We also present a
diagrammatic method that permits us to write the spectral determinant in terms
of a finite number of periodic orbit contributions. These results are
generalized to the case of graphs in a magnetic field. Several examples
illustrating this formalism are presented and its application to the
thermodynamic and transport properties of weakly disordered and coherent
mesoscopic networks is discussed.Comment: 33 pages, submitted to Ann. Phy
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