Two-pion-exchange in the non-mesonic weak decay of $\Lambda$-hypernuclei

Abstract

The non-mesonic weak decay of $\Lambda$--hypernuclei is studied within a one-meson-exchange potential supplemented by a chirally motivated two-pion-exchange mechanism. The effects of final state interactions on the outgoing nucleons are also taken into account. In view of the severe discrepancies between theoretical expectations and experimental data, particular attention is payed to the asymmetry of the protons emitted by polarized hypernuclei. The one-meson-exchange model describes the non-mesonic rates and the neutron-to-proton ratio satisfactorily but predicts a too large and negative asymmetry parameter. The uncorrelated and correlated two-pion mechanisms change the rates moderately, thus maintaining the agreement with experiment. The modification in the strength and sign of some decay amplitudes becomes crucial and produces asymmetry parameters which lie well within the experimental observations.

20 pages, 3 figures Uses elsart.cls

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Cited by in corpus (11)

• Strangeness in nuclear physics
• Strangeness nuclear physics: a critical review on selected topics
• Exchange terms in the two--nucleon induced non--mesonic weak decay of $\Lambda$--hypernuclei
• Single and double coincidence nucleon spectra in the weak decay of Lambda hypernuclei
• Current constraints on the EFT for the ΛN --> N N transition
• Microscopic approach to the proton asymmetry in the non-mesonic weak decay of Lambda-hypernuclei
• Relationships between nonmesonic-weak-decays in different hypernuclei
• Nonmesonic weak decay spectra of ${}_{\Lambda }^4$He
• Nonmesonic Weak Decay Dynamics from proton spectra of $\Lambda$-Hypernuclei
• Nonmesonic weak decay of charmed hypernuclei
• Effects of $\Lambda \Lambda -\Xi N$ mixing in the decay of $S=-2$ hypernuclei