135,313 research outputs found

### Infinite Nuclear Matter on the Light Front: A Modern Approach to Brueckner Theory

Understanding an important class of experiments requires that light-front
dynamics and related light cone variables k^+ and k_perp be used. If one uses
k^+ as a momentum variable, the corresponding canonical spatial variable is
x^-=x^0-x^3 and the time variable is x^0+x^3. This is the light front (LF)
approach of Dirac. A relativistic light front formulation of nuclear dynamics
is developed and applied to treating infinite nuclear matter in a method which
includes the corelations of pairs of nculeons. This is light front Brueckner
theory.Comment: 7 pages, text of an invited talk presented at the 10th International
Conference on Recent Progress In Many-Body Theories. To be published by World
Scientific as volume 3 of "Series on Advances in Quantum Many-Body Theory",
eds. R.F. Bishop, C.E. Campbell, J.W. Clark and S. Fanton

### Resonant relativistic corrections and the A_y problem

We study relativistic corrections to nuclear interactions caused by boosting
the two-nucleon interaction to a frame in which their total momentum does not
vanish. These corrections induce a change in the computed value of the
neutron-deuteron analyzing power A_y that is estimated using the plane-wave
impulse approximation. This allows a transparent analytical calculation that
demonstrates the significance of relativistic corrections. Faddeev calculations
are however needed to conclude on the A_y puzzle.Comment: 8 pages, 2 figures, minor addition, to appear in Phys. Rev.

### Tensor-polarized quark and antiquark distribution functions in a spin-one hadron

To understand orbital-angular-momentum contributions is becoming crucial for
clarifying nucleon-spin issue in the parton level. Twist-two structure
functions b_1 and b_2 for spin-one hadrons could probe orbital-angular-momentum
effects, which reflect a different aspect from current studies for the spin-1/2
nucleon, since they should vanish if internal constituents are in the S state.
These structure functions are related to tensor structure in spin-one hadrons.
Studies of such tensor structure will open a new field of high-energy spin
physics. The structure functions b_1 and b_2 are described by tensor-polarized
quark and antiquark distributions delta_T-q and delta_T-qbar. Using HERMES data
on the b_1 structure function for the deuteron, we made an analysis of
extracting the distributions delta_T-q and delta_T-qbar in a simple x-dependent
functional form. Optimum distributions are proposed for the tensor-polarized
valence and antiquark distribution functions from the analysis. A finite tensor
polarization is obtained for antiquarks if we impose a constraint that the
first moments of tensor-polarized valence-quark distributions vanish. It is
interesting to investigate a physics mechanism to create a finite
tensor-polarized antiquark distribution.Comment: 4 pages, LaTeX, 2 eps figures, Phys. Rev. D in pres

### Pionic Color Transparency

We use a semi-classical approximation to investigate the effects of color
transparency on pion electroproduction reactions. The resulting reduced nuclear
interactions produce significant, but not dominating, differences with the
results of conventional distorted-wave, Glauber-type treatments at kinematics
accessible to Jefferson Laboratory. Nuclear effects that could mimic the
influence of color transparency are also discussed.Comment: 10 pages, 6 figure

- â€¦