A previously introduced relativistic energy density functional, successfully applied to ordinary nuclei, is extended to hypernuclei. The density-dependent mean field and the spin–orbit potential are consistently calculated for a Λ hyperon in the nucleus 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 Σ hyperon in the intermediate state. Scalar and vector mean fields reflecting in-medium changes of the quark condensates are constrained by QCD sum rules. The model, applied to oxygen as a test case, describes spectroscopic data in good agreement with experiment. In particular, the smallness of the Λ spin–orbit interaction finds a natural explanation in terms of an almost complete cancellation between scalar–vector background contributions and long-range terms generated by two-pion exchange.
In-medium chiral SU(3) dynamics and hypernuclear structure / P. Finelli; N. Kaiser; D. Vretenar; W. Weise. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - STAMPA. - 658:(2007), pp. 90-94. [10.1016/j.physletb.2007.09.070]
In-medium chiral SU(3) dynamics and hypernuclear structure
FINELLI, PAOLO;
2007
Abstract
A previously introduced relativistic energy density functional, successfully applied to ordinary nuclei, is extended to hypernuclei. The density-dependent mean field and the spin–orbit potential are consistently calculated for a Λ hyperon in the nucleus 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 Σ hyperon in the intermediate state. Scalar and vector mean fields reflecting in-medium changes of the quark condensates are constrained by QCD sum rules. The model, applied to oxygen as a test case, describes spectroscopic data in good agreement with experiment. In particular, the smallness of the Λ spin–orbit interaction finds a natural explanation in terms of an almost complete cancellation between scalar–vector background contributions and long-range terms generated by two-pion exchange.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.