Christoph Best

Pion and Rho Structure Functions from Lattice QCD

We calculate the lower moments of the deep-inelastic structure functions of the {pi} and the {rho} meson on the lattice. Of particular interest to us are the spin-dependent structure functions of the {rho}. The calculations are done with Wilson fermions and for three values of the quark mass, so that we can perform an extrapolation to the chiral limit. {copyright} {ital 1997} {ital The American Physical Society}

Pair creation in transport equations using the equal-time Wigner function

Based on the equal-time Wigner function for the Klein-Gordon field, we discuss analytically the mechanism of pair creation in a classical electromagnetic field including back reaction. It is shown that the equations of motion for the Wigner function can be reduced to a variable-frequency oscillator. The pair-creation rate results then from a calculation analogous to barrier penetration in nonrelativistic quantum mechanics. The Wigner function allows one to utilize this treatment for the formulation of an effective transport theory for the back-reaction problem with a pair-creation source term including Bose enhancement.

π and ρ structure functions from lattice QCD

We calculate the lower moments of the deep-inelastic structure functions of the {pi} and the {rho} meson on the lattice. Of particular interest to us are the spin-dependent structure functions of the {rho}. The calculations are done with Wilson fermions and for three values of the quark mass, so that we can perform an extrapolation to the chiral limit. {copyright} {ital 1997} {ital The American Physical Society}

Algebraic multigrid operators for disordered systems and lattice gauge theory

Most of the computer time in simulating lattice gauge theories [1] is spent on calculating Green’s functions of the fermion matrix. Similar disordered matrix problems appear in many other branches of physics. The algebraic multigrid method can be used to construct coarse-grid approximations to disordered linear lattice operators which improve the performance of a variety of numerical algorithms.

U(1) flux tube profiles from Hamiltonian lattice gauge theory using a random walk ground-state projector

We use a self-guided random walk to solve the ground-state problem of Hamiltonian U(1) pure gauge theory in 2+1 dimensions in the string sector. By making use of the electric-field representation, we argue that the spatial distribution of the electric field can be more easily measured than in ordinary Monte Carlo simulations.

The deep-inelastic structure functions of π and ϱ mesons☆

Abstract We compute the lower moments of the structure functions of π and ϱ. Of particular interest are the spin-dependent structure functions of the ϱ as they give new information about quark binding effects.

πandρstructure functions from lattice QCD

We calculate the lower moments of the deep-inelastic structure functions of the {pi} and the {rho} meson on the lattice. Of particular interest to us are the spin-dependent structure functions of the {rho}. The calculations are done with Wilson fermions and for three values of the quark mass, so that we can perform an extrapolation to the chiral limit. {copyright} {ital 1997} {ital The American Physical Society}

A microscopic semiclassical confining field equation forU(1) lattice gauge theory in 2+1 dimensions

We present a semiclassical nonlinear field equation for the confining field in 2+1-dimensionalU(1) lattice gauge theory (compact QED). The equation is derived directly from the underlying microscopic quantum Hamiltonian by means of truncation. Its nonlinearities express the dynamic creation of magnetic monopole currents leading to the confinement of the electric field between two static electric charges. We solve the equation numerically and show that it can be interpreted as a London relation in a dual superconductor.