Hypernuclei and in-medium chiral dynamics |
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Authors: | P Finelli |
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Institution: | (1) Physics Department, University of Bologna, via Irnerio 46, 40126 Bologna, Italy |
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Abstract: | A recently introduced relativistic nuclear energy density functional,
constrained by features of low-energy QCD, is extended
to describe the structure of hypernuclei.
The density-dependent mean field and the spin-orbit potential
of a Λ-hyperon in a nucleus,
are consistently calculated using the SU(3) extension of in-medium
chiral perturbation theory.
The leading long-range ΛN interaction arises from
kaon-exchange and 2π-exchange with a Σ-hyperon
in the intermediate state.
Scalar and vector mean fields, originating from in-medium changes
of the quark condensates, produce
a sizeable short-range spin-orbit interaction.
The model, when applied to oxygen as a test case,
provides a natural explanation for the
smallness of the effective Λ spin-orbit potential: an almost complete
cancellation between the background contributions (scalar and vector) and
the long-range terms generated by two-pion exchange. |
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Keywords: | |
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