551 research outputs found
Lattice Charge Overlap: Towards the Elastic Limit
A numerical investigation of time-separated charge overlap measurements is
carried out for the pion in the context of lattice QCD using smeared Wilson
fermions. The evolution of the charge distribution function is examined and the
expected asymptotic time behavior , where
represents the charge density relative time separation, is clearly visible in
the Fourier transform. Values of the pion form factor are extracted using
point-to-smeared correlation functions and are seen to be consistent with the
expected monopole form from vector dominance. The implications of these results
for hadron structure calculations is briefly discussed.Comment: 8 pages, 7 figures appended as ps file
Structure Functions, Form Factors, and Lattice QCD
We present results towards the calculation of the pion electric form factor
and structure function on a lattice using charge overlap. By
sacrificing Fourier transform information in two directions, it is seen that
the longitudinal four point function can be extracted with reasonable error
bars at low momentum.Comment: 3 pages (contribution to "Lattice 93"), UNIX SHAR file includes the
LaTeX source and three encapsulated PS figures (which will print on
appropriate drivers but can not be previewed), BU-HEP-93-0
Disconnected Electromagnetic Form Factors
Preliminary results of a calculation of disconnected nucleon electromagnetic
factors factors on the lattice are presented. The implementation of the
numerical subtraction scheme is outlined. A comparison of results for electric
and magnetic disconnected form factors on two lattice sizes with those of the
Kentucky group is presented. Unlike previous results, the results found in this
calculation are consistent with zero in these sectors.Comment: Lattice 2000 (Hadronic Matrix Elements), 4 pages, 6 fig
Finite Volume Effects in Self Coupled Geometries
By integrating the pressure equation at the surface of a self coupled
curvilinear boundary, one may obtain asymptotic estimates of energy shifts,
which is especially useful in lattice QCD studies of nonrelativistic bound
states. Energy shift expressions are found for periodic (antiperiodic) boundary
conditions on antipodal points, which require Neumann (Dirichlet) boundary
conditions for even parity states and Dirichlet (Neumann) boundary conditions
for odd parity states. It is found that averaging over periodic and
antiperiodic boundary conditions is an effective way of removing the asymptotic
energy shifts from the boundary. Asymptotic energy shifts from boxes with self
coupled walls are also considered and shown to be effectively antipodal. The
energy shift equations are illustrated by the solution of the bounded harmonic
oscillator and hydrogen atoms.Comment: 17 pages LaTeX, to appear in Ann. Phy
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