63 research outputs found
Orbital Angular Momentum in Scalar Diquark Model and QED
We compare the orbital angular momentum of the 'quark' in the scalar diquark
model as well as that of the electron in QED (to order {\alpha}) obtained from
the Jaffe-Manohar de- composition to that obtained from the Ji relation. We
estimate the importance of the vector potential in the definition of orbital
angular momentum
A Study of Heavy-Light Mesons on the Transverse Lattice
We present results from a study of meson spectra and structure in the limit
where one quark is infinitely heavy. The calculations, based on the framework
of light-front QCD formulated on a transverse lattice, are the first
non-perturbative studies of B-mesons in light-front QCD. We calculate the
Isgur-Wise form factor, light-cone distribution amplitude, the heavy-quark
parton distribution function and the leptonic decay constant of B-mesons.Comment: 5 pages, 3 figures, Revtex, corrected typos, added references,
included moment
Wilson Fermions on a Transverse Lattice
In the light-front formulation of field theory, it is possible to write down
a chirally invariant mass term. It thus appears as if one could solve the
species doubling problem on a light-front quantized transverse lattice in a
chirally invariant way. However, upon introducing link fields and after
renormalizing, one finds exactly the same LF Hamiltonian as if one had started
from the standard Wilson action in the first place. The (light-front) chirally
invariant transverse lattice regularization is thus not chirally invariant in
the conventional sense. As an application of the Wilson formulation for
fermions on a lattice, we calculate spectrum, distribution functions
and distribution amplitudes for mesons below in a truncated Fock space.Comment: 14 pages, RevTe
Photon Generalized Parton Distributions
We present a calculation of the generalized parton distributions of the
photon using overlaps of photon light-front wave functions.Comment: Talk given at LightCone 2011, 4 pages, 3 figure
Chiral Condensate and Short-Time Evolution of QCD(1+1) on the Light-Cone
Chiral condensates in the trivial light-cone vacuum emerge if defined as
short-time limits of fermion propagators. In gauge theories, the necessary
inclusion of a gauge string in combination with the characteristic light-cone
infrared singularities contain the relevant non-perturbative ingredients
responsible for formation of the condensate, as demonstrated for the 't Hooft
model.Comment: 4 pages, Revtex
Application of Pauli-Villars regularization and discretized light-cone quantization to a single-fermion truncation of Yukawa theory
We apply Pauli-Villars regularization and discretized light-cone quantization
to the nonperturbative solution of (3+1)-dimensional Yukawa theory in a
single-fermion truncation. Three heavy scalars, including two with negative
norm, are used to regulate the theory. The matrix eigenvalue problem is solved
for the lowest-mass state with use of a new, indefinite-metric Lanczos
algorithm. Various observables are extracted from the wave functions, including
average multiplicities and average momenta of constituents, structure
functions, and a form factor slope.Comment: 21 pages, 7 figures, RevTeX; published version: more extensive data
in the tables of v
Femto-Photography of Protons to Nuclei with Deeply Virtual Compton Scattering
Developments in deeply virtual Compton scattering allow the direct
measurements of scattering amplitudes for exchange of a highly virtual photon
with fine spatial resolution. Real-space images of the target can be obtained
from this information. Spatial resolution is determined by the momentum
transfer rather than the wavelength of the detected photon. Quantum photographs
of the proton, nuclei, and other elementary particles with resolution on the
scale of a fraction of a femtometer is feasible with existing experimental
technology.Comment: To be published in Physical Review D. Replaces previous version with
minor changes in presentatio
Nucleon Generalized Parton Distributions and Holographic Models
Using ideas from Light Front Holography, we discuss the calculation of the
nucleon helicity-independent generalized parton distributions of quarks in the
zero skewness case.Comment: Prepared for LIGHTCONE 2011, 23 - 27 May, 2011, Dalla
Generalized Parton Distributions at x->1
Generalized parton distributions at large are studied in perturbative QCD
approach. As and at finite , there is no dependence for the
GPDs which means that the active quark is at the center of the transverse
space. We also obtain the power behavior: for pion; and
for nucleon, where
represents the additional dependence on .Comment: 7 pages, 2 figure
Transverse lattice calculation of the pion light-cone wavefunctions
We calculate the light-cone wavefunctions of the pion by solving the meson
boundstate problem in a coarse transverse lattice gauge theory using DLCQ. A
large-N_c approximation is made and the light-cone Hamiltonian expanded in
massive dynamical fields at fixed lattice spacing. In contrast to earlier
calculations, we include contributions from states containing many gluonic
link-fields between the quarks.The Hamiltonian is renormalised by a combination
of covariance conditions on boundstates and fitting the physical masses M_rho
and M_pi, decay constant f_pi, and the string tension sigma. Good covariance is
obtained for the lightest 0^{-+} state, which we identify with the pion. Many
observables can be deduced from its light-cone wavefunctions.After perturbative
evolution,the quark valence structure function is found to be consistent with
the experimental structure function deduced from Drell-Yan pi-nucleon data in
the valence region x > 0.5. In addition, the pion distribution amplitude is
consistent with the experimental distribution deduced from the pi gamma^* gamma
transition form factor and diffractive dissociation. A new observable we
calculate is the probability for quark helicity correlation. We find a 45%
probability that the valence-quark helicities are aligned in the pion.Comment: 27 pages, 9 figure
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