TY - JOUR
T1 - The quadrupole term of the Lorentz-Lorenz effect in pionic atoms
AU - Warszawski, J.
AU - Eisenberg, J. M.
AU - Gal, A.
PY - 1978/12/27
Y1 - 1978/12/27
N2 - Two-nucleon contributions to the pion-nucleus p-wave optical potential at zero energy, not included in the standard Lorentz-Lorenz treatment, are considered. Such contributions involve coupling the external pion momenta k and k′, which appear in the optical potential, to form a quadrupole term, and their neglect would appear to be justified only in a strict long-wavelength limit for the pion. The contribution of these quadrupole terms to the observed shifts of pionic atom energy levels is evaluated for 27Al and 40Ca, under the assumption of short-range repulsive nucleon-nucleon correlations, and found to constitute roughly between 10% and 15% of the standard Lorentz-Lorenz contribution, or 5% to 7% of the observed shifts.
AB - Two-nucleon contributions to the pion-nucleus p-wave optical potential at zero energy, not included in the standard Lorentz-Lorenz treatment, are considered. Such contributions involve coupling the external pion momenta k and k′, which appear in the optical potential, to form a quadrupole term, and their neglect would appear to be justified only in a strict long-wavelength limit for the pion. The contribution of these quadrupole terms to the observed shifts of pionic atom energy levels is evaluated for 27Al and 40Ca, under the assumption of short-range repulsive nucleon-nucleon correlations, and found to constitute roughly between 10% and 15% of the standard Lorentz-Lorenz contribution, or 5% to 7% of the observed shifts.
UR - http://www.scopus.com/inward/record.url?scp=49349118363&partnerID=8YFLogxK
U2 - 10.1016/0375-9474(78)90589-4
DO - 10.1016/0375-9474(78)90589-4
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AN - SCOPUS:49349118363
SN - 0375-9474
VL - 312
SP - 253
EP - 264
JO - Nuclear Physics A
JF - Nuclear Physics A
IS - 3
ER -