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HK: Physik der Hadronen und Kerne

HK 10: Postersitzung: Theorie

HK 10.12: Poster

Dienstag, 20. März 2001, 10:30–12:45, R

Chiral 3π-Exchange NN-Potentials — •Norbert Kaiser — Physik-Department, Technische Universität München, 85747 Garching

We calculate in chiral perturbation theory the static nucleon-nucleon potentials generated by the chiral three-pion exchange between nucleons [1]. It is sufficient to compute the mass-spectra (i.e. the imaginary parts) of the relevant two-loop diagrams. The spin-spin and tensor potentials proportional to g_A⁶ require however a special treatment since their mass-spectra start with a non-vanishing value at the 3π-threshold. As a surprise we find that the total isoscalar central 3π-exchange potential vanishes identically. The individually largest 3π-exchange potentials are isoscalar spin-spin and tensor potentials and an isovector central potential. For these simple analytical expressions can be given and their values at r=1 fm are 3.9 MeV, 2.3 MeV and 1.2 MeV. Altogether, one finds negligibly small corrections from chiral 3π-exchange in the region r≥ 1.4 fm where 1π-exchange and chiral 2π-exchange alone give a very good description of the strong NN-force. This has recently been demonstrated in a phase shift analysis of the Nijmegen group [2].

[1] N. Kaiser, Phys. Rev. C61, 014003 (2000); C62 024001 (2000).

[2] M. Rentmester et al., Phys. Rev. Lett. 82 4992 (1999). Supported in part by BMBF and DFG