On relativistic approaches to the pion self-energy in nuclear matter
Departamento de Física Teórica, Universidad de Valencia 46100 Burjassot (Valencia), Spain
2 Institute of Terrestrial Magnetism Ionosphere and Radio Wave Propagation RAS, 142190, Troitsk, Moscow Region, Russia
3 Departamento de Física Teórica and IFIC, Universidad de Valencia 46100 Burjassot (Valencia), Spain
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We argue that, in contrast to the non-relativistic approach, a relativistic evaluation of the nucleon-hole and delta-isobar-nucleon-hole contributions to the pion self-energy incorporates the s-wave scattering, whose magnitude within the RPA is in conflict with the near-threshold behavior imposed by chiral symmetry. As a result, a relativistic approach to the pion self-energy in isospin-symmetric nuclear matter, containing only these diagrams, does not satisfy the known experimental results on the near-threshold behavior of the -nucleon (forward) scattering amplitude.
© Società Italiana di Fisica and Springer-Verlag, 2004