2008 APS April Meeting and HEDP/HEDLA Meeting
Volume 53, Number 5
Friday–Tuesday, April 11–15, 2008;
St. Louis, Missouri
Session D4: Few Body Nuclear Physics II
1:30 PM–3:18 PM,
Saturday, April 12, 2008
Hyatt Regency St. Louis Riverfront (formerly Adam's Mark Hotel),
Room: Promenade B
Sponsoring
Units:
DNP GFB
Chair: Wayne Polyzou, University of Iowa
Abstract ID: BAPS.2008.APR.D4.1
Abstract: D4.00001 : The Three-Nucleon Analyzing Power Puzzle - The Past 20 Years*
1:30 PM–2:06 PM
Preview Abstract
Abstract
Author:
Werner Tornow
(Duke University \& TUNL)
The three-nucleon (3N) analyzing power A$_{y}$($\theta$) puzzle
(3NAPP) refers to the failure of rigorous 3N calculations to
account for the magnitude of the measured nucleon-deuteron A$_
{y}$($\theta$) in the angular region of the A$_{y}$ maximum
(~30\% underprediction). The 3NAPP is a low-energy phenomenon
and does not refer to A$_{y}$($\theta$) in the energy range
above 100 MeV, where standard 3N forces contribute
significantly to A$_{y}$($\theta$) in the angular region of the
cross-section minimum. The 3NAPP was discovered by Wita{\l}a,
Gl\"{o}ckle and Cornelius in 1987 when they compared their
rigorous 3N calculations to the neutron-deuteron (n-d) data of
the T\"{u}bingen/TUNL group, although some evidence of a
possible problem with describing A$_{y}$($\theta$) was already
reported in 1986 by Koike and Haidenbauer. Before 1995 the
3NAPP was solely a n-d scattering phenomenon. However, with the
Coulomb problem solved in 3N calculations by Kievsky, Viviani
and Rosati in 1995 for energies below, and in 1999 for energies
above the deuteron breakup threshold, the 3NAPP entered a new
stage and included A$_{y}$($\theta$) in proton-deuteron (p-d)
scattering as well as the vector analyzing power iT$_{11}
$($\theta$)
in d-p scattering. Although p-d phase-shift analyses and their
comparison to theoretical phase shifts provided some insight
into the physics of the 3NAPP, the accurate p-d data initially
created a new problem at energies below about 5 MeV, until the
theoretical treatment of the magnetic moment interaction by
Wita{\l}a et al. and Kievsky et al. provided a uniform picture.
The recent inclusion of relativity in 3N calculations by
Wita{\l}a et al. has increased the 3NAPP at low energies
considerably (by about 25\% at 5 MeV). Furthermore, the new n-d
A$_{y}$($\theta$) data obtained by Weisel et al. at TUNL
confirmed our conjecture that the transition region between 20
MeV and about 35 MeV, above which the 3NAPP disappears, is
poorly understood. Here, p-d data are needed to make progress.
Currently, the hope is that the 3N force terms predicted by
Chiral Effective Filed Theory in N3LO will eventually provide
the correct explanation of the 3NAPP. However, the range of the
required 3N force terms has to be about 3 fm in order to
describe the A$_{y}$($\theta$) and iT$_{11}$($\theta$) data at
E$_
{c.m.}$=432 keV.
*Work supported by US DOE, Office of Nuclear Physics, Grant \# DE-FG02-97ER41033
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.APR.D4.1