2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009;
Denver, Colorado
Session A1: Plenary Session I
8:30 AM–10:18 AM,
Saturday, May 2, 2009
Room: Plaza Ballroom ABC
Sponsoring
Unit:
APS
Chair: Curt Callan, Princeton University
Abstract ID: BAPS.2009.APR.A1.2
Abstract: A1.00002 : What have we learned using the CEBAF microscope to study hadronic matter?
9:06 AM–9:42 AM
Preview Abstract
Abstract
Author:
Kent Paschke
(University of Virginia)
High-energy electrons are a remarkably clean probe of hadronic matter,
essentially providing a microscope for examining atomic nuclei and the
strong nuclear force. For more than a decade, the Continuous Electron Beam
Accelerator Facility (CEBAF) at Jefferson Lab (JLab) has been a leading
facility for such investigations, resulting in a number of surprising
discoveries and a substantive refinement of our understanding of the
nucleon, its underlying quark structure, and the dynamics of the strong
interaction.
The insights gained from research at JLab cover a broad range of length
scales, monitored by the 4-momentum transfer Q$^{2}$, in elastic, inelastic,
and deeply inelastic scattering regimes. One notable discovery has been the
unexpected Q$^{2}$ variation of the ratio of the proton elastic form-factors
G$^{p}_{E}$ / G$^{p}_{M}$, which suggests an important contribution from
quark orbital angular momentum to the spin of the nucleon. This finding is
further supported by spin-dependent deep-inelastic measurements, which also
appear to require significant contributions from quark orbital angular
momentum. Another notable achievement is the unambiguous observation of
proton-neutron correlations in nuclei, a clear signature of the short-range
piece of the nucleon-nucleon potential. This fulfills a long-standing quest
in electron scattering and provides crucial input to the description of
cold, dense nuclear matter ranging from terrestrial nuclei to neutron stars.
Investigations at JLab have also benefitted from unconventional techniques,
such as the use of parity-violation to access weak neutral current
interactions as a probe of nuclear matter. This approach, which was employed
in a sensitive search for contributions of virtual strange quarks to the
nucleon charge and magnetic distributions, also yields significant new
constraints on physics beyond the Standard Model.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.APR.A1.2