2,962 research outputs found
Recent results in chiral effective field theory for the NN system
I describe recent progress towards a theory of the NN force which captures
the consequences of QCD's chiral symmetry and the pattern of its breaking, and
is formulated as an expansion in a ratio of low and high mass scales,
M_{lo}/M_{hi}. This "chiral effective field theory" of the NN system is a firm
foundation for explorations of nuclear structure and reactions that are
grounded in QCD's low-energy symmetries. While calculations that use a ChiPT
expansion for the NN potential have proven very successful, they can only be
used with a narrow range of momentum-space cutoffs, which leaves the expansion
parameter for observable quantities somewhat murky. Here we seek a truly
systematic effective field theory for the NN amplitude, that is manifestly
renormalization-group invariant at each order in a demonstrably perturbative
expansion.Comment: Invited talk at the 7th International Workshop on Chiral Dynamics,
August 6-10, 2012, Jefferson Lab, Newport News, VA. To appear in the
proceedings. 12 pages, 5 figure
The nucleon-nucleon system in chiral effective theory
I discuss the conditions under which the application of chiral perturbation
theory to the NN potential gives reliable results for NN scattering phase
shifts. ChiPT also yields a convergent expansion for the deuteron charge
operator. For cutoffs < 1 GeV, this produces precise predictions for
deuterium's quadrupole and charge form factors in the range Q^2 < 0.25 GeV^2.Comment: 4 pages, 4 figures. Contribution to Proceedings of "12th
International Conference on Meson-Nucleon Physics and the Structure of the
Nucleon", Williamsburg, VA, May 31-June 4, 201
Electron-deuteron scattering in a relativistic theory of hadrons
We review a three-dimensional formalism that provides a systematic way to
include relativistic effects including relativistic kinematics, the effects of
negative-energy states, and the boosts of the two-body system in calculations
of two-body bound-states. We then explain how to construct a conserved current
within this relativistic three-dimensional approach. This general theoretical
framework is specifically applied to electron-deuteron scattering both in
impulse approximation and when the meson-exchange current is
included. The experimentally-measured quantities , , and are
calculated over the kinematic range that is probed in Jefferson Lab
experiments. The role of both negative-energy states and meson retardation
appears to be small in the region of interest.Comment: 17 pages, 4 figures, uses BoxedEPS.tex, lamuphys.sty, bibnorm.sty. To
appear in the proceedings of the Workshop on Electron-Nucleus Scattering held
at the Elba International Physics Center, June 199
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